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Can domestic fowl, Gallus gallus domesticus, show self-control?

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Can domestic fowl, Gallus gallus domesticus, show self-control?

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Abstract

An important aspect of cognition is whether animals live exclusively in the present or can anticipate the future. Defined as self-control, the ability to choose a large, remote reinforcer over a small, proximate reinforcer available at the same frequency has been examined in a number of species, often proving difficult to demonstrate. We investigated self-control for food in domestic fowl using a standard two-key operant task and an equivalent two-choice return maze (TCRM) task. When hens chose between a 2-s delay to a 3-s feed access (impulsive) and a 6-s delay to a 7-s feed access (self-control), they appeared unable to discriminate in the TCRM but were impulsive in the operant task. We explored reasons for not choosing self-control in the operant task, first by examining the relation between feed access time and actual feed intake. A second operant experiment examined whether failure to show self-control could be attributed to an inability to combine the delay and access (quantity) reward information associated with choices to reach overall predictions of value. New hens chose between a 2-s delay to a 3-s feed access (impulsive) and either a 22-s delay to a 22-s feed access (standard self-control) or a 6-s delay to a 22-s feed access (jackpot self-control). While hens were impulsive in the standard condition, they showed significant and pronounced self-control in the jackpot condition, eliminating the possibility of an absolute cognitive constraint. Impulsive behaviour can instead be explained by temporal discounting: perceived depreciation of reward value as a function of the uncertainty associated with delay. Implications for welfare are discussed.

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... Sophisticated cognitive abilities are also used by fowl in non-social contexts. Fowl show the self-control needed to wait for larger delayed reward instead of going for the immediate gratification of an instant small reward [127]. In humans, self-control positively correlates with cognitive ability [128]. ...
... This, in turn, suggests that they possess self-awareness (reviewed in [9]). Fowl also appear to use sophisticated trade-off calculations between time and reward size, which humans can only manage past four years of age [129], to decide whether it is worthwhile to wait [127]. When the reward size was increased from close in size to the instant reward to a much larger 'jackpot', the number of tested hens that waited for the larger reward increased from 22% to 93% [127]. ...
... Fowl also appear to use sophisticated trade-off calculations between time and reward size, which humans can only manage past four years of age [129], to decide whether it is worthwhile to wait [127]. When the reward size was increased from close in size to the instant reward to a much larger 'jackpot', the number of tested hens that waited for the larger reward increased from 22% to 93% [127]. ...
Article
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The world’s most numerous bird, the domestic chicken, and their wild ancestor, the red junglefowl, have long been used as model species for animal behaviour research. Recently, this research has advanced our understanding of the social behaviour, personality, and cognition of fowl, and demonstrated their sophisticated behaviour and cognitive skills. Here, we overview some of this research, starting with describing research investigating the well-developed senses of fowl, before presenting how socially and cognitively complex they can be. The realisation that domestic chickens, our most abundant production animal, are behaviourally and cognitively sophisticated should encourage an increase in general appraise and fascination towards them. In turn, this should inspire increased use of them as both research and hobby animals, as well as improvements in their unfortunately often poor welfare.
... Avian self-control has been investigated in an array of delay-of-gratification tasks that require refraining from an immediate, smaller gain in favor of a delayed, larger gain (also termed delay discounting; [1]). Delay of gratification across bird species has been tested in delay maintenance tasks (e.g., [163,164], delay choice tasks (e.g., [165][166][167]), and the patch-leaving task [168,169]. ...
... In delay choice or intertemporal choice tasks, the individual is required to wait for a more attractive reward or signal opting out, e.g., by pressing a button, to receive an immediate, less attractive reward (e.g., [165][166][167][168][169]177]). ...
... Table 2. Overview of EF tasks tested with bird species. [6,7,[24][25][26][27][28]30,37,41,42,54,55,62,72,80,[97][98][99][100][101][102][103][104]111,[114][115][116][117]119,[124][125][126][128][129][130][131][133][134][135][136]140,142,148,149,[152][153][154][155][157][158][159][161][162][163][164][165][166][167][168][169][170][171][172][173][174][176][177][178]180,[184][185][186]188,189,191,193,194,[197][198][199][200][201][202][205][206][207][209][210][211][279][280][281][282][283]288,289,[291][292][293][294][295][296][297][298][299][300][301][302][303]. [200] Domestic Pigeon (Columba livia) [129,193,194,197 [231,275] Orange-winged Amazon (Amazona amazonica) Inhibition [30] Cognitive Flexibility [30] Rainbow Lorikeet (Trichoglossus haemotodus) ...
Article
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Executive functions comprise of top-down cognitive processes that exert control over information processing, from acquiring information to issuing a behavioral response. These cogni- tive processes of inhibition, working memory, and cognitive flexibility underpin complex cognitive skills, such as episodic memory and planning, which have been repeatedly investigated in several bird species in recent decades. Until recently, avian executive functions were studied in relatively few bird species but have gained traction in comparative cognitive research following MacLean and colleagues’ large-scale study from 2014. Therefore, in this review paper, the relevant previous findings are collected and organized to facilitate further investigations of these core cognitive processes in birds. This review can assist in integrating findings from avian and mammalian cognitive research and further the current understanding of executive functions’ significance and evolution.
... There is evidences for the lack of foraging opportunities (Dawkins, 1989; Huber-Eicher and Wechsler, 1998;Rodenburg and Koene, 2004) and perching opportunities (Olson and Keeling, 2000;Heikkilä, et al., 2006;Wichman, et al., 2007) contributing to the manifestation of these behaviours. In addition to this, there is emerging behavioural evidence for higher cognitive abilities in avian species (Regolin, et al., 1995;Bugnyar and Kotrschal, 2002;Pepperberg, 2004;Taylor, et al., 2002;Abeyesinghe, et al., 2005), and also physiological evidence of homologous structures in the avian brain compared to those of mammals (Emery and Clayton, 2004;Butler, et al., 2005) that are associated with the capacity for the subjective experience of emotions and conscious awareness. This therefore causes concerns that animals kept in barren environments are likely to experience suffering (Désiré, et al., 2002). ...
... One question regarding cognitive abilities is whether animals live solely in the present, or whether they can somehow anticipate the future. This has been investigating in a number of species, mainly pigeons, rats and primates, by attempting to measure whether they can show self-control; that is, resisting a reward that provides instant gratification for a later benefit (Abeyesinghe, et al., 2005). Taylor, et al. (2002) concluded that hens may be able to estimate a six minute delay to reward when given a visual clue. ...
... Taylor, et al. (2002) concluded that hens may be able to estimate a six minute delay to reward when given a visual clue. This was investigated further by Abeyesinghe, et al. (2005) by testing the self-control paradigm in hens using an operant key pecking method. Hens reacted impulsively during the first few trials; however, a final trial tested them with a six second delay to a 22 second feed access, where they showed significant self-control. ...
Research
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MSc thesis investigating whether cognitive bias is present in domestic hens when kept in a standard environment (enclosure with features similar to the enriched cage) vs an enriched environment (enclosure with features that go above and beyond the enriched cage).
... Nevertheless, a handful of domesticated species have been tested in delay of gratification paradigms to assess their self-control abilities. On a group level, dogs waited between four to 25 times longer (Leonardi et al., 2012;Brucks et al., 2017b;Range et al., 2020) compared to pigs (Zebunke et al., 2018;Krause et al., 2021) and chicken (Abeyesinghe et al., 2005); however, domesticated animals generally exhibited rather low self-control abilities compared to other non-domesticated species (e.g., longtailed macaques: Pelé et al., 2010;cleaner wrasse: Aellen et al., 2021). While certainly differences in experimental procedures and paradigms are accountable for some variation (Susini et al., 2021), more data on domesticated species' self-control abilities, in particular of farm animals, is needed in order to better understand whether and how domestication affected selfcontrol abilities. ...
... In Experiment 1, the horses waited on average for 36.1 s (median: 40 s), while in Experiment 2, the average of the maximally tolerated delay was 13.4 s (median: 10 s) in the quality condition and 15.1 s (median: 10 s) in the quantity condition. In both experiments, a number of horses successfully waited for 60 s, while, for example, dogs waited for up to 15 min (Leonardi et al., 2012;Brucks et al., 2017b), pigs up to 20 s (Zebunke et al., 2018), chicken up to 7 s (Abeyesinghe et al., 2005). Other non-domesticated species, however, tolerated much higher delay times [e.g., long-tailed macaques: 21 min (Pelé et al., 2010), cleaner wrasse: 480 s (Aellen et al., 2021), ravens: 640 s (Hillemann et al., 2014), and cuttlefish: 130 s (Schnell et al., 2021)]. ...
Article
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Self-control, defined as the ability to forgo immediate satisfaction in favor of better pay-offs in the future, has been extensively studied, revealing enormous variation between and within species. Horses are interesting in this regard because as a grazing species they are expected to show low self-control whereas its social complexity might be linked to high self-control abilities. Additionally, self-control may be a key factor in training and/or coping with potentially stressful husbandry conditions. We assessed horses’ self-control abilities in a simplified delay of gratification test that can be easily implemented in a farm setting. In Experiment 1, we gave horses (N = 52) the choice between an immediately available low-quality reward and a delayed high-quality reward that could only be obtained if the horse refrained from consuming the immediate reward. Different experimenters (N = 30) that underwent prior training in the procedures, tested horses in two test phases either with their eyes visible or invisible (sunglasses). Twenty horses waited up to the maximum delay stage of 60 s while all horses performed worse in the second test phase. In Experiment 2, we improved the test procedure (i.e., one experimenter, refined criterion for success), and tested 30 additional horses in a quality and quantity condition (one reward vs. delayed bigger reward). Two horses successfully waited for 60 s (quality: N = 1, quantity: N = 1). Horses tolerated higher delays, if they were first tested in the quantity condition. Furthermore, horses that were fed hay ad libitum, instead of in a restricted manner, reached higher delays. Coping behaviors (e.g., looking away, head movements, pawing, and increasing distance to reward) facilitated waiting success and horses were able to anticipate the upcoming delay duration as indicated by non-random distributions of giving-up times. We found no correlations between owner-assessed traits (e.g., trainability and patience) and individual performance in the test. These results suggest that horses are able to exert self-control in a delay of gratification paradigm similar to other domesticated species. Our simplified paradigm could be used to gather large scale data, e.g., to investigate the role of self-control in trainability or success in equestrian sports.
... For example, relative degrees of self-control are typically higher in non-human great apes (henceforth apes), corvids and parrots [12][13][14][15][16][17][18]. By contrast, other taxa such as some monkey species, rodents, chickens and pigeons [19][20][21][22][23][24] find it difficult to inhibit the consumption of a desirable food item for a delayed gain and thus exhibit relatively lower degrees of self-control. Increased delayed gratification abilities have been attributed to a variety of factors including lifehistory characteristics, whereby larger species with lower metabolisms and longer life expectancies can potentially tolerate longer delays [25]. ...
... Note that abandon times in our subjects were relatively long compared to other species in previous studies [19][20][21][22][23][24]27]. The elevated self-control observed in cuttlefish might have emerged as a by-product of selection on unrelated phenotypic traits. ...
Article
The ability to exert self-control varies within and across taxa. Some species can exert self-control for several seconds whereas others, such as large-brained vertebrates, can tolerate delays of up to several minutes. Advanced self-control has been linked to better performance in cognitive tasks and has been hypothesized to evolve in response to specific socio-ecological pressures. These pressures are difficult to uncouple because previously studied species face similar socio-ecological challenges. Here, we investigate self-control and learning performance in cuttlefish, an invertebrate that is thought to have evolved under partially different pressures to previously studied vertebrates. To test self-control, cuttlefish were presented with a delay maintenance task, which measures an individual's ability to forgo immediate gratification and sustain a delay for a better but delayed reward. Cuttlefish maintained delay durations for up to 50–130 s. To test learning performance, we used a reversal-learning task, whereby cuttlefish were required to learn to associate the reward with one of two stimuli and then subsequently learn to associate the reward with the alternative stimulus. Cuttlefish that delayed gratification for longer had better learning performance. Our results demonstrate that cuttlefish can tolerate delays to obtain food of higher quality comparable to that of some large-brained vertebrates.
... Conversely, if animals were shown to have sophisticated mental time travel abilities, this should dramatically alter how we view their capacity for suffering and poor welfare. Similar suggestions have since been made by others (Duncan and Petherick, 1991;Suddendorf and Busby, 2003a; UK Companion Animal Welfare Council (CAWC), 2003; Mendl and Paul, 2004;Abeyesinghe et al., 2005) including Lea (2001) who, assuming that the facility of language allows mental time travel, wrote ''If I hurt a non-linguistic animal, perhaps I only hurt it for as long as the pain lasts: if I hurt a linguistic animal, I cause it to fear for as long as it can see the pain coming, I hurt it for as long as the pain lasts, and I cause it to smart with recollected pain for as long as the memory lasts. So every hurt is multiplied, as it were, by three-in fact, if we wanted to be quantitative, perhaps by much more.' ...
... Furthermore, some studies do indicate that, under the right conditions animals can reverse this preference (e.g. chickens, Abeyesinghe et al., 2005). This may indicate some ability for episodic future thinking although, if so, it is only for a few seconds into the future, clearly tied to current motivational state, and hence would not be considered by some as strong evidence (Clayton et al., 2003a). ...
Article
The importance of understanding the mental experiences of animals in order to assess their welfare was recognised by the 1965 UK Brambell Committee Report. The report further suggested that the extent to which animals live life in the present moment has a major impact on their capacity for suffering. Limited ability to recall previous events and imagine future ones would protect animals from the worry, ‘rumination’ and associated emotional disorders that contribute so much to human suffering. We investigate these suggestions in the light of new evidence on the capacity of animals to travel mentally through time, and with reference to the subjective experiences of human amnesic patients who are indeed ‘stuck in time’, living their lives in the present. The key human abilities for mental time travel are episodic memory and episodic future thinking, characterised by an ability to place events in time (what, where, when (www)), and to consciously recall or imagine these events. Tests of www memory, recollection vs. familiarity memory, single-trial learning, episodic vs. semantic encoding, and forward planning have been used to investigate whether such cognitive systems also exist in animals. The evidence indicates that some studied species show behaviour consistent with the capacity for mental time travel, while others do not. The extent to which animals consciously experience mental time travel remains unknown. In terms of the implications for welfare, research on human amnesics with damage to brain structures involved in episodic memory suggests that animals lacking mental time travel would miss the beneficial consequences of using previous experience to plan and organise future behaviour, but also the detrimental consequences of being able to ruminate on the recalled past and worry about the imagined future. Emotional responses, including future-directed anxiety would be temporally bound by the presence of relevant stimuli or cues and, therefore, potentially short-lived. However past experiences could, through the actions of non-episodic memory systems attributable to other brain structures, still impact on emotional state via (implicit) learning of associations between cues and emotional events. Cumulative effects of past experience on stress response mechanisms and baseline stress or mood states would also be expected to occur. Mental time travel may thus bring both welfare benefits and problems. Absence of this ability by no means releases animals from many effects of the environment, including the past, on their emotional state.
... Domestic chickens, too, show the capacity for selfcontrol in an experimental setting. In a situation where they are given a choice between a 2-s delay followed by access to food for 3 s or a 6-s delay followed by access for 22 s (a veritable jackpot), hens held out for the larger reward, demonstrating rational discrimination between different future outcomes while employing self-control to optimize those outcomes (Abeyesinghe et al. 2005). Given the promising results of this study, more exploration of the cognitive basis of self-control in chickens is indicated. ...
... As discussed above, chickens show self-control in experimental situations (Abeyesinghe et al. 2005) which require them to forgo an immediate reward for a later larger reward. Some authors have argued that self-control is indicative of self-awareness (Genty et al. 2004), as it tends to emerge reliably in humans at around the age of four, when other cognitive capacities related to self-awareness (e.g., mirror self-recognition) have either developed or are developing (Mischel et al. 1989). ...
Article
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Domestic chickens are members of an order, Aves, which has been the focus of a revolution in our understanding of neuroanatomical, cognitive, and social complexity. At least some birds are now known to be on par with many mammals in terms of their level of intelligence, emotional sophistication, and social interaction. Yet, views of chickens have largely remained unrevised by this new evidence. In this paper, I examine the peer-reviewed scientific data on the leading edge of cognition, emotions, personality, and sociality in chickens, exploring such areas as self-awareness, cognitive bias, social learning and self-control, and comparing their abilities in these areas with other birds and other vertebrates, particularly mammals. My overall conclusion is that chickens are just as cognitively, emotionally and socially complex as most other birds and mammals in many areas, and that there is a need for further noninvasive comparative behavioral research with chickens as well as a re-framing of current views about their intelligence.
... In a pio-neering study, human children aged 3 to 4 years old could earn an additional marshmallow by resisting the temptation of eating a single one for 15 min (Mischel, Ebbesen, & Zeiss, 1972). A variety of paradigms have since been used to assess the ability to delay gratification in nonhuman animals, mostly accumulation tasks (Beran, 2002;Evans, Beran, Paglieri, & Addessi, 2012;Grosch, Neuringer, & Grosch, 1981;Vick, Bovet, & Anderson, 2010), delay choice tasks (Abeyesinghe, Nicol, Hartnell, & Wathes, 2005;Ainslie, 1974;Cheng, Peña, Porter, & Irwin, 2002;Logue & Peña-Correal, 1985;Van Haaren, Van Hest, Van De Poll, Rats, & Nanne, 1988), or hybrid delay tasks (Beran et al., 2014;Paglieri et al., 2013). While all of the previously mentioned paradigms only entail waiting to get the maximum reward, food exchange tasks (Dufour & Sterck, 2008;Dufour, Wascher, Braun, Miller, & Bugnyar, 2012;Koepke, Gray, & Pepperberg, 2015;Leonardi, Vick, & Dufour, 2012;Ramseyer, Pelé, Dufour, Chauvin, & Thierry, 2006) require a more active approach of the subjects-they have to hold on to a food item they receive from the experimenter and resist eating it to be able to trade it in for a better (quality exchange) or larger (quantity exchange) reward after a given time delay. ...
... While early delay of gratification experiments in birds showed hardly any capacity to wait (Abeyesinghe et al., 2005;Ainslie, 1974;Logue & Peña-Correal, 1985;Vick et al., 2010), recently results similar to those observed in eutherian mammals were shown in a food exchange task in corvids, where common ravens (Corvus corax) waited almost 3 min (160 s), and carrion crows (Corvus corone) even more than 5 min (320 s) to exchange for better-quality food . The delay before consuming the initial item in failed trials (renouncement time) was significantly shorter than expected by chance, suggesting that the birds did not merely reach the limits of their patience, but decided whether to wait or not. ...
Article
The ability to forego an immediate reward in favor of a bigger or better one at a later point has been linked with advanced cognitive skills, such as impulse control and forward-planning, and can be assessed by the classic food exchange paradigm. While the ability to perform in such tasks has long been regarded as an exclusive trait of humans and some mammals, that is, primates and dogs, in recent years some bird species have been found to perform similarly as primates. Here we test 10 captive kea (Nestor notabilis), using a food exchange paradigm standardized in earlier experiments, but adding the use of a container to hold the initial item. The subjects reached waiting times of up to 160 s. They also showed significantly different results depending on the difference in the preference level for the presented food items, as well as clearly nonrandom waiting times, displaying forward-planning and economic evaluation of the situation at hand. As in most other species, results were markedly better when exchanging for quality as opposed to quantity. These results provide further evidence for temporal discounting in birds and fit in with the data gained on corvids and parrots in recent years. (PsycINFO Database Record
... Avian self-control has been investigated in an array of delay-of-gratification tasks that require refraining from an immediate, smaller gain in favour of a delayed, larger gain (also termed delay discounting; [1]). Delay of gratification across bird species has been tested in delay maintenance tasks (e.g., [183][184], delay choice tasks (e.g., [185][186][187]) and the patch-leaving task [188][189][190][191] (Table 2). ...
... In delay choice or intertemporal choice tasks, the individual is required to wait for a more attractive reward or signal opting out, e.g., by pressing a button, to receive an immediate, less attractive reward (e.g., [185][186][187][188][189]199]). ...
Preprint
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Simple Summary: Everyday functioning requires dealing with a lot of information, usually so smoothly that we barely notice it. The processes that support smooth processing of such information are called executive functions. In recent years, researchers have become interested in these processes in birds, whom, although long considered "bird-brained" and less clever than mammals, actually parallel mammals in tests of intellectual prowess. Interest in birds' brains and performance is increasing , but an overview of relevant previous findings is lacking. Therefore, in this paper, relevant findings are collected and organized to support further investigations of executive functions in birds. Abstract: Executive functions comprise top-down cognitive processes that exert control over information processing, from acquiring information to issuing a behavioural response. These cognitive processes of inhibition, working memory and shifting underpin complex cognitive skills, such as episodic memory and planning, which have been repeatedly investigated in several bird species in recent decades. Until recently, avian executive functions were studied in relatively few bird species, but have gained traction in comparative cognitive research following MacLean and colleagues' large-scale study (2014). Therefore, in this review paper, relevant previous findings are collected and organized to facilitate further investigations of these core cognitive processes in birds. This review can assist in integrating findings from avian and mammalian cognitive research and further current understanding of executive functions' significance and evolution.
... Instead of attempting to define sentience through cognition, a wiser approach would be to utilise the knowledge and understanding of animal cognition to reduce suffering, and to increase the positive states of animals who are known to be sentient [14,25]. For example, using knowledge of cognitive processes to understand whether an animal can remember a positive or negative experience, and to predict how he or she will react to similar experiences in the future, can be used to positively impact their future welfare [2,26]. An understanding of cognition can therefore be helpful and beneficial in improving welfare, but it should not be used as a sole measure upon which protection is offered or denied. ...
Article
Full-text available
Simple Summary Animal sentience refers to the ability of animals to experience pleasurable states such as joy, and aversive states such as pain and fear (Broom, D.M. Dis. Aquat. Org. 2007, 75, 99–108). The science of animal sentience underpins the entire animal welfare movement. Demonstrating objectively what animals are capable of is key to achieving a positive change in attitudes and actions towards animals, and a real, sustainable difference for animal welfare. This paper briefly summarises understanding of animal sentience through the ages. There follows a review of the current state of animal sentience, and concluding thoughts on its future in regards to animal welfare. Abstract The science of animal sentience underpins the entire animal welfare movement. Demonstrating objectively what animals are capable of is key to achieving a positive change in attitudes and actions towards animals, and a real, sustainable difference for animal welfare. This paper briefly summarises understanding and acceptance of animal sentience through the ages. Although not an exhaustive history, it highlights some of the leading figures whose opinions and work have most affected perspectives of animal sentience. There follows a review of the current state of animal sentience, what is known, and what the main limitations have been for the development of the study of sentience. The paper concludes with some thoughts for the future of the science, and where it should be going in order to most benefit animal welfare.
... This plasticity could facilitate the habituation of young LSR quail to an unstable social condition and reduce their emotional reactivity when placed in an unknown situation. It is likely that the quail chicks exposed to repeated social changes had come to expect these changes as it is known that domestic fowl can anticipate (Izawa et al., 2003;Abeyesinghe et al., 2005). Quail chicks emotional reactivity could have decreased in order to prevent the development of a chronic stress state or the expression of strong reactions to further changes in their social environment. ...
... This plasticity could facilitate the habituation of young LSR quail to an unstable social condition and reduce their emotional reactivity when placed in an unknown situation. It is likely that the quail chicks exposed to repeated social changes had come to expect these changes as it is known that domestic fowl can anticipate (Izawa et al., 2003;Abeyesinghe et al., 2005). The decrease in the emotional reactivity of the LSR chicks may be the consequence of a psychophysiological adjustment which could prevent the development of a chronic stress state or the expression of strong reactions to further changes in their social environment. ...
Article
Repeated encounters with unfamiliar conspecifics in large groups of domestic birds create a potentially stressful social environment which can affect the birds’ emotional reactivity and consequently their welfare. As social relationships between young quail are particularly influenced by their social motivation (i.e., the motivation to seek close proximity with conspecifics), it is likely that the reaction of quail to repeated encounters with strangers depends on their social motivation. The aim of this study was to assess the emotional reactivity of quail chicks with high (HSR) or low (LSR) social motivation housed under stable and unstable social conditions. Quail chicks were housed either in stable pairs, i.e. remaining with the same cagemate until testing (NHSR=19 and NLSR=18 pairs), or in unstable pairs, i.e. changing cagemate daily from 6 to 13 days of age (NHSR=20 and NLSR=19 pairs). Emotional reactivity was measured using a novel object test on day 14, and an emergence test and a tonic immobility test on day 15. The social condition affected the number of induction attempts of quail chicks in the tonic immobility test but only in the LSR ones. This number of inductions was lower under the stable than under the unstable social condition in this line. Moreover, the HSR chicks showed greater disturbance than the LSR ones in the three behavioural tests. In conclusion, social instability did not affect the emotional reactivity of HSR quail chicks, which was high, regardless of social condition. In contrast, repeated cagemate changes seemed to decrease the emotional reactivity of LSR quail chicks. These results suggest that low social motivation makes easier the adaptation to the potential social instability encountered in large flocks.
... Increasing research on the perceptual and cognitive abilities of the domestic fowl provides supportive evidence that chickens are able to make rational choices. Experiments have shown, for example, that chickens are able to 'plan ahead' and forego a small immediate reward in order to obtain a delayed but larger reward (Abeyesinghe et al., 2005). It is also known that chickens have some object 'permanence' ability. ...
Article
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We review the behavioural needs, priorities and preferences of laying hens for increased space, perching, nesting, foraging and dustbathing behaviour. Hens make full use of and may work to gain access to perches, however it is not yet known how perching ranks in comparison with otherbehaviours. Laying hens appearto have an instinctive need to perform pre-laying (nest-building) behaviour and have a strong preference for a discrete, enclosed nest site, for which they will work hard to gain access as oviposition approaches. Access to a nest site is a high-ranking priority for laying hens, preferred over food at this time. Foraging is a behavioural need, with peat, sand and wood shavings preferred substrates in choice experiments. There is no reduction in time spent foraging when a cost is imposed, nor when feed is freely available. Dustbathing is currently viewed as a behavioural need, as the extent to which hens value dustbathing is not known. Bird preferences for space are complex and confounded by interactions between group size and stocking density. There is some evidence that priority for space varies during the day and increases when the total space available to a group of birds is restricted, and that greater priority is given to space than to small group size. The presence of apparently purposeless behaviour, of high levels of aggression or redirected behaviours such as feather pecking and cannibalism are indicators that the housing system is not meeting the behavioural needs of the hens and hence is not satisfactory forbird welfare. Full text also at: https://www.tandfonline.com/eprint/ZTXGRHRJACYI3TURV3RK/full?target=10.1079/WPS200598
... Outcome impulsivity revolves around the inability to deal with delay of gratification, and has been researched in the contexts of substance abuse, gambling, attention deficit hyperactivity disorder (ADHD) and aggression [4][5][6]. In humans, outcome impulsivity has been investigated through questionnaire based measures [7][8][9], whereas in rodents and birds, it has been studied through operant conditioning paradigms [6,[10][11][12] which is the approach also adopted here. ...
... The ability to inhibit the impulse to accept an instant option in anticipation for a delayed, more valuable one has long been believed to be a uniquely human attri- bute [1]. Indeed, rodents and most birds tested wait only few seconds for a delayed gain, and many monkeys wait less than a minute [2][3][4][5][6][7]. Some primates and dogs (possibly as an effect of domestication) do, however, accept delays over a minute and even show outstanding plasticity in decision-making relative to the benefits involved [8][9][10][11]. ...
Article
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Evidence for flexible impulse control over food consumption is rare in non-human animals. So far, only primates and corvids have been shown to be able to fully inhibit the consumption of a desirable food item in anticipation for a gain in quality or quantity longer than a minute. We tested Goffin cockatoos (Cacatua goffini) in an exchange task. Subjects were able to bridge delays of up to 80 s for a preferred food quality and up to 20 s for a higher quantity, providing the first evidence for temporal discounting in birds that do not cache food.
... When subjects opt for the delayed option, they have no further opportunity to modify their responses during the entire duration of the trial. In such tasks, domestic fowl (Gallus gallus), pigeons (Columbia livia), and rats (Rattus norvegicus) opted for the small immediate reward when the delay exceeded a few seconds (Abeyesinghe et al. 2005; Mazur 1987; Richards et al. 1997). Marmosets (Callithrix jacchus) and tamarins (Saguinus oedipus) postponed gratification for 5–20 s (Stevens et al. 2005a), whereas long-tailed macaques (Macaca fascicularis) and brown capuchins (Cebus apella) waited ca. ...
... Psychologists have found high levels of discounting (suggesting impulsivity) in rats, several species of monkey, lemurs, nonhuman apes, jays, chickens, bumblebees, and other animals (e.g., Abeyesinghe, Nicol, Hartnell, & Wathes, 2005;Ainslie, 1974;Bateson & Kacelnik, 1996;Cheng, Peña, Porter, & Irwin, 2002;McDiarmid & Fig. 1 (A) Schematic of the structure of the standard intertemporal choice task. On each trial, the subject chooses between a smaller sooner (SS) and a larger later (LL) option. ...
Article
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Animals are an important model for studies of impulsivity and self-control. Many studies have made use of the intertemporal choice task, which pits small rewards available sooner against larger rewards available later (typically several seconds), repeated over many trials. Preference for the sooner reward is often taken to indicate impulsivity and/or a failure of self-control. This review shows that very little evidence supports this assumption; on the contrary, ostensible discounting behavior may reflect a boundedly rational but not necessarily impulsive reward-maximizing strategy. Specifically, animals may discount weakly, or even adopt a long-term rate-maximizing strategy, but fail to fully incorporate postreward delays into their choices. This failure may reflect learning biases. Consequently, tasks that measure animal discounting may greatly overestimate the true discounting and may be confounded by processes unrelated to time preferences. If so, animals may be much more patient than is widely believed; human and animal intertemporal choices may reflect unrelated mental operations; and the shared hyperbolic shape of the human and animal discount curves, which is used to justify cross-species comparisons, may be coincidental. The discussion concludes with a consideration of alternative ways to measure self-control in animals.
... Once the choice is made, subjects have no further opportunity to modify their response during the entire duration of the trial. Pigeons (Columbia livia: Mazur 1987), domestic fowl (Gallus gallus: Abeyesinghe et al. 2005) and rats (Rattus norvegicus: Richards et al. 1997) opt for the small immediate reward when the delay surpasses a duration of a few seconds. Monkeys like marmosets (Callithrix jacchus) and tamarins (Saguinus oedipus) can delay gratiWcation between 5 and 20 s (Stevens et al. 2005b). ...
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The ability of animals to delay gratiWcation is crucial for complex goal-directed action. It may help them in making eVective decisions when facing a choice. We tested the ability of nine long-tailed macaques (Macaca fas-cicularis) to delay gratiWcation in several experiments. In exchange tasks, subjects had to keep a small piece of cookie before returning it to an experimenter in order to get a larger food amount. Results showed that animals could wait between 10 s and 10 min depending on individual and sizes of reward. In another experiment, subjects could immediately give back the initial piece of cookie then wait for the return. Their performances more than doubled, demonstrating the role of consumption inhibition in postponing gratiWcation. Such achievements underscore delays of grati-Wcation which until now were not thought possible in monkeys. Finally, subjects were presented with an accumulation of food pieces added at short intervals until they seized them. They mostly waited between 30 s and 1 min, which points at the consistency of our data, compared to those of other studies. Our results indicate that long-tailed macaques anticipated the duration of delays. We may account for their remarkable performances by their achievements in the social context.
... Impulse control develops slowly in children (Mischel et al., 1989) and often represents serious difficulties to non-human animals (Stephens and Anderson, 2001;Stevens et al., 2005;Evans and Beran, 2007a;Anderson et al., 2010). This is particularly true for several bird species, which hardly control an impulsive choice for longer than a few seconds in experimental situations (pigeons, Columba livia: Ainslie, 1974;Mazur, 1987;Logue et al., 1988;Green et al., 2004; African gray parrots, Psittacus erithacus: Vick et al., 2010; domestic fowl, Gallus gallus: Abeyesinghe et al., 2005). ...
... Using Method 1, on every occasion a hen made a choice it was confined for a short period of time in its chosen environment. This confinement may force the animal to weigh-up the consequences of its choice, something that chickens are able to do, at least in operant self-control experiments (Abeyesinghe et al., 2005). Using Method 2, there were few contingent consequences of entering an environment. ...
Article
Preference tests are a widely used method in animal welfare science but the influence of specific methodologies has not been widely investigated, and methods are often selected arbitrarily. In these experiments we assessed the environmental preferences of 72 individual laying hens, where environments contained either a foraging box (F), an element of mild risk presented by an insect-shaped robot (R) or both (FR). Preferences were assessed for paired sets of environments (F vs FR; FR vs R; F vs R) in a balanced sequential design. Two different methods were used, a discrete-choice procedure using a T-maze where choices were followed by a short confinement period in the chosen environment and a free-access procedure where hens were free to move through a tunnel between the two environments of a pair. The discrete-choice method revealed an overall preference ranking F > FR > R, with a high level of transitivity expressed between sets. The free-access method did not detect the mild aversion to R and revealed an overall preference ranking F = FR > R, with a much weaker level of transitivity expressed between sets. The additional control provided by the free-access method, meaning that hens could leave the R environment whenever they wished, may have significantly reduced the aversiveness of the R stimulus. Such influences need to be considered when selecting a preference testing method in an animal welfare context.
... Comparatively little attention is paid to the mental or affective state of the animal and meat chicken welfare research published in international peerreviewed journals focuses almost exclusively on outcome-based measures of health ( Barnett and Glatz, 2004). The majority of studies of welfare that incorporate measures of meat chicken behaviour and cognitive function are conducted in the UK and their trading partners ( Abeyesinghe et al., 2005). There is comparatively more behavioural research conducted in the US in relation to meat chicken welfare, where market consolidation is comparatively less than that experienced in Australia and New Zealand. ...
Article
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Welfare issues and approaches are compared in the following review, for all major meat chicken producing countries. In certain countries, such as the United States and Australia, the industry comprises a small number of integrated, self-regulated companies, whereas in Europe the industry is more diverse, with greater competition, and more government regulation. There is much more meat chicken welfare research and regulation in Europe, and in particular the United Kingdom, than in countries with self-regulated industries, such as the United States, even taking into account the level of meat chicken production in the relevant areas. By contrast, welfare regulation in two of the world's major meat chicken producing countries; namely Brazil and China, is negligible. Some welfare issues are regional, such as high temperatures which are particularly problematic for free range birds, breeds selected for rapid growth and when birds are removed from fully-housed systems. However, similar welfare issues affect intensively-housed birds worldwide, which comprise the majority of animals produced. These include rapid growth rates, predisposing birds to heart and leg problems, especially ascites and sudden death syndrome, and high stocking densities, which inhibit locomotion and environmental exploration, predisposing birds to contact dermatitis. Welfare research in Europe has shown that highly stocked birds spend longer sleeping, congregate around feeders and are more fearful, as well as experiencing higher ammonia levels, which irritate their eyes and respiratory systems. The review concludes that intensive systems present similar welfare issues worldwide; however, European research is more directed to the behavioural and cognitive requirements of the birds, than in self-regulated countries. This will enable their industry to respond better to future welfare requirements from consumers.
... Domestic chickens have highly developed cognitive abilities, showing evidence of declarative representation (Regolin et al. 1995; Forkman 2000), object permanence (Freire & Nicol 1999; Freire et al. 2004), self-control (Abeyesinghe et al. 2005) and highly developed social-learning abilities (for reviews see Nicol 2004, 2006). These abilities are employed flexibly, depending on the context and the social identity of both the observer and the demonstrator. ...
Article
We previously demonstrated that domestic hens, Gallus gallus domesticus, show behavioural and phys-iological responses when witnessing mild chick distress, and possess the underlying foundations of emotional empathy. However, no studies have determined how cognitive influences affect empathic processes in birds. A fundamental question is whether a mother hen's response to chick distress is mediated by her knowledge about the situation or by chick distress cues. We therefore investigated how manipulating hen and chick knowledge influences hens' responses to chick distress. Each hen's brood of chicks was split into three groups, based on whether they had the same, opposite or no knowledge about a potentially threatening situation (environmental cues signalling air puff administration). We compared hens' behavioural, vocal and physiological responses (heart rate, heart rate variability and surface body temperature) to actual and perceived threat to their chicks. Hens increased maternal vocalizations and walking, and decreased preening, when they perceived their chicks to be threatened, regardless of the chicks' reactions to the situation. Hens exhibited signs of stress-induced hyperthermia only when their perception of threat was in accordance with that of their chicks. Chick behaviour was influenced by the hens' expectations, with all chick groups spending more time distress vocalizing and less time preening when in the environment that the hen associated with threat. We conclude that the protective maternal response of domestic hens is not solely driven by chick distress cues; rather, hens integrate these with their own knowledge to produce a potentially adaptive, flexible and context-dependent response.
... Other evidence shows that domestic chickens have at least a limited capacity to plan for future events, since they can inhibit impulsive responding to immediate stimuli. 32 These examples alert us to the likelihood that this capacity is much more common in animals than thought previously. ...
Animals exhibit species-typical adaptations of behavior and may suffer stress in captivity if they are prevented from performing these patterns of behavior. This article considers whether these particular 'needs' rely on cognitive processes or are performed without complex cognition despite their appearance of behavioral complexity. Emotion and cognition in animals are also discussed, particularly whether animals can feel emotions and, if so, what ranges of emotions they might feel. Cognitive capacities that would contribute to suffering include empathy with the suffering of others, memories of negative events and suffering in anticipation of future events. Cognitive bias of individual animals toward positive or negative feelings is related to dominance of the left or right hemisphere, respectively. These biases might be reflected in the animal's preferred limb to pick up food. Hence, limb preference could be a useful measure of cognitive bias. Post-traumatic stress disorder is a cognitive condition that, it is suggested, might involve dominance of the right hemisphere. This debilitating condition is experience-dependent and not infrequently seen in animals in captivity. In conclusion, it is argued that there is an obvious need for more research on cognition as it relates to animal welfare and as a basis for changing legislature to protect animals from suffering. Copyright © 2010 John Wiley & Sons, Ltd. For further resources related to this article, please visit the WIREs website. Copyright © 2010 John Wiley & Sons, Ltd.
... Indeed, this shows that P birds were not impaired in task performance, as they were able to wait periods of unpredictable time (pre-cue period) without pecking a key, and they were able to suppress a prepotent motor response to the No-Go stimulus (false alarms, efficiency) similarly to NP birds. This mirrors the conclusions of a self-control study conducted in laying hens where birds anticipated future consequences by displaying high temporal cognitive abilities 35 . It is important to highlight that the present study was conducted solely in adult birds as FP behaviour is more mainly reported and observed in adult birds 7,14,36,37 . ...
Article
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Repetitive feather pecking (FP) where birds peck and pull out feathers of conspecifics could reflect motor impulsivity through a lack of behavioural inhibition. We assessed motor impulsivity in female chickens (n = 20) during a Go/No-Go task where birds had to peck (Go) or inhibit pecks (No-Go) appropriately to obtain a food reward, depending on visual cues in an operant chamber. Birds were selected to show divergent FP performance based on their genotype (high predisposition for FP or unselected control line) and phenotype (peckers or non-peckers). Genotype, phenotype, and its interaction did not affect the number of pre-cue responses, percentage of responses during No-Go cues (false alarms), or efficiency (number of rewards over number of responses). We present the first documentation of a Go/No-Go task to measure the ability of birds genetically and phenotypically selected for FP activity to inhibit a prepotent motor response. Results indicate that the repetitive motor action of FP does not reflect impulsivity and is not genetically linked to a lack of behavioural inhibition as measured in a Go/No-Go task.
... Similarly, the traditional view of chickens as having no sense of the past or future has been undone by studies involving food-control trials. In such studies chickens consistently prefer waiting longer for a larger food jackpot, an outcome which requires them to be able to discriminate between shorter and longer waiting times (Abeyesinghe et al. 2005;Taylor et al. 2002). These and other findings disputing the limited view of chicken cognition are now well documented in avian cognition research (Rogers and Kaplan 2004: vii;Regolin et al. 2005). ...
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Recent decades have witnessed the rise of chefs to a position of cultural prominence. This rise has coincided with increased consciousness of ethical issues pertaining to food, particularly as they concern animals. We rank cookbooks by celebrity chefs according to the minimum number of sentient animals that must be killed to make their recipes. On our stipulative definition, celebrity chefs are those with their own television show on a national network in the United States, the United Kingdom, Canada or Australia. Thirty cookbooks by 26 such chefs were categorized according to the total number of cows, pigs, chicken, fish and other species they included as ingredients. The total number of animals killed was divided by the number of non-dessert recipes to generate an average number of animal deaths per recipe for each book. We outline the rationale for our project and its methodology before presenting a ranked table of 30 cookbooks by celebrity chefs. This method generates several interesting findings. The first concerns the wide variation in animal fatalities among cookbooks. The chef with the heaviest animal footprint killed 5.25 animals per recipe, while the omnivorous chef with the smallest footprints killed 0.19 per recipe. Clearly, not all approaches to meat eating are equal when it comes to their animal mortality rate. Pigs and large ruminants are all substantially bigger than poultry, which are themselves bigger than many fish. The prime determinant of a chef’s place in the index was the number of small animals his or her recipes required. Whether a chef cooked in the style of a particular cuisine (Italian, French, Mexican etc.), by contrast, had no discernible influence on his or her ranking. We analyze how different chefs present themselves—as either especially sensitive or insensitive to ethical issues involving animals and food—and note cases where these presentations do or do not match their index ranking.
... Möglicherweise fiel es den Tieren der Gruppe "Qualität" leichter, auf die "bessere" Belohnung zu warten (Hillemann et al. 2014). Die Motivation war demnach höher, länger auf die bessere Belohnung zu warten, als auf die gleiche Belohnung in der größeren Menge (Abeyesinghe et al. 2005, Ramseyer et al. 2006, Dufour et al. 2012, Hillemann et al. 2014). ...
Conference Paper
Impulse control is the ability to resist the impulse taking an immediate but smaller/ worse reward instead of choosing a delayed but bigger/better reward. Only one study showed that pigs have the ability to show impulse control. The present study first examined whether there are differences in impulse control when the food reward differs in quality or quantity. After weaning, 20 female pigs were divided into two equally sized groups: "quality" (better vs. worse reward) and "quantity" (smaller vs. bigger reward). After the habituation phase, including a food preference test, the discrimination phase was performed. There the pigs learned to discriminate between better/worse and bigger/ smaller reward. Then the impulse control was tested applying a delay maintenance test. It was observed that pigs in the quality group showed higher impulse control (delay 32 s, two animals) in contrast to the quantity group (delay 16 s, two animals). Moreover both groups showed different strategies to cope with an increase in delay. More knowledge about impulse control could lead towards better animal welfare in pig farming.
... Specifically, neural networks considered analogous or functionally homologous to mammalian networks involved in sensory integration, long-term memory, associative learning, and emotion have been identified in birds (e.g., The Avian Brain Nomenclature Consortium, 2005; Güntürkün, 2012;Marzluff et al., 2012;Shanahan et al., 2013;Clayton and Emery, 2015). Birds also show complex and flexible behavioral responses, reflecting high-level cognitive processes such as sophisticated problem solving, long-term memory, learning, theory of mind, social reasoning, and emotion generation (reviewed by Butler and Cotterill, 2006;Mashour and Alkire, 2013;Clayton and Emery, 2015;Pennartz et al., 2019), including in domestic chickens (e.g., Nicol and Pope, 1994;Hogue et al., 1996;Gyger and Marler, 1998;Vallortigara et al., 1998;D'eath and Stone, 1999;Abeyesinghe et al., 2005;Nicol et al., 2009;Zimmerman et al., 2011;McCabe, 2019). Some of these cognitive skills rival or even exceed those demonstrated by nonhuman primates, such as the creation and application of tools by New Caledonia crows (Corvus moneduloides), use and comprehension of human language by African gray parrots (Psittacus erithacus), and self-recognition by magpies (Pica pica) (e.g., Pepperberg, 2007;Prior et al., 2008;von Bayern et al., 2018). ...
Chapter
An animal's welfare state represents the dynamic integration of its various mental experiences, both negative and positive, i.e., how it is experiencing its own life. Birds are unequivocally aware of their own mental experiences (i.e., sentient and conscious) and thus their welfare should be considered. The purpose of this chapter is to introduce animal welfare as a subject amenable to scientific scrutiny, present a framework for systematic assessment of welfare state, and illustrate how the capacity of birds for specific mental experiences relevant to welfare can be rigorously evaluated. Most avian welfare research to date has focused on commercial poultry species because of the large number of birds involved and the multiple ways in which their welfare is compromised. Thus, we present a case study evaluating the potential for chickens to have unpleasant mental experiences such as breathlessness and anxiety/fear when exposed to carbon dioxide stunning prior to slaughter.
... Chickens can exercise self-control [17] and can show signs of emotional frustration [18]. ...
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Animals play many important roles in humans’ lives. They are a source of food, compan-ionship and wealth. Increasing global demand for food has resulted in the intensification of livestock production. Intensive production systems are aimed at maximising profits by rearing more animals on smaller pieces of land in order to produce more food. The other systems of animal production are semi-intensive and extensive production systems. Of the three systems, the semi-intensive system offers the best option for enhancing ani-mal welfare in all species. Animal welfare can be defined in many ways depending on people’s views of animals. The underlying theme of animal welfare is to enhance physi-cal and mental health of animals. Despite improvements in livestock farming techniques over the years, the welfare of farm animals remains a major concern. The major welfare concerns in the livestock industry relate to the rearing and management of dairy calves; the rearing of sows in gestation and farrowing crates; the housing of layer chickens in battery cages and the restriction of feed in broiler parent stock. Good animal husbandry is a basis for promoting the welfare of animals.
... This appears first directly after hatching with remarkable filial imprinting (Bolhuis, 1991) and continues throughout life, for example, in foraging contexts, where chickens learn to orientate, (re)locate specific food resources, or can be trained in artificial situations to use operant feeders (Nicol, 2015). Understanding the cognitive abilities of chickens and other livestock animals can have crucial impact on their husbandry and production and thus on their welfare (Nicol, 1996;Abeyesinghe et al., 2005;Smith and Johnson, 2012). As humans tend to expect animals with greater cognitive similarities to humans to be more likely to suffer (Serpell, 2004;Smith and Johnson, 2012), which is, from a scientific perspective, not reasonable (Dawkins, 2001). ...
Article
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The intense selection of chickens for production traits, such as egg laying, is thought to cause undesirable side effects and changes in behavior. Trade-offs resulting from energy expenditure in productivity may influence other traits: in order to sustain energetic costs for high egg production, energy expenditure may be redirected away from specific behavioral traits. For example, such energetic trade-offs may change the hens' cognitive abilities. Therefore, we hypothesized highly productive laying hens to show reduced learning performance in comparison to moderate productive lines. We examined the learning ability of four chicken lines that differed in laying performance (200 versus 300 eggs/year) and phylogenetic origin (brown/white layer; respectively, within performance). In total 61 hens were tested in semi-automated Skinner boxes in a three-phase learning paradigm (initial learning, reversal learning, extinction). To measure the hens' learning performance within each phase, we compared the number of active decisions needed to fulfill a learning criteria (80% correct choices for learning, 70% no responses at extinction) using linear models. Differences between the proportions of hens per line that reached criterion on each phase of the learning tasks were analyzed by using a Kaplan-Meier (KM) survival analysis. A greater proportion of high productive hens achieved the learning criteria on each phase compared to less productive hens (Chi 2 3 = 8.25, p = 0.041). Furthermore, high productive hens accomplished the learning criteria after fewer active decisions in the initial phase (p = 0.012) and in extinction (p = 0.004) compared to the less selected lines. Phylogenetic origin was associated with differences in learning in extinction. Our results contradict our hypothesis and indicate that the selection for productivity traits has led to changes in learning behavior and the high productive laying hens possessed a better learning strategy compared to moderate productive hens in a feeding-rewarding context. This better performance may be a response to constraints resulting from high selection as it may enable these hens to efficiently acquire additional energy resources. Underlying mechanisms for this may be directly related to differences in neuronal structure or indirectly to foraging strategies and changes in personality traits such as fearfulness and sociality.
... Intertemporal choice tasks are similar to the exchange task though without the exchange component and typically require close interaction with experimenter, as subjects can wait for a better reward, or press a button to receive an immediate, less preferred reward. These tasks have been broadly applied across species, for example, via two-key operant tasks to investigate the phenomenon of temporal discounting, that is, the devaluation of rewards over time, including in primates Rosati et al., 2007;Stevens & Mühlhoff, 2012), domestic fowl (Gallus gallus domesticus) (Abeyesinghe, Nicol, Hartnell, & Wathes, 2005), pigeons (Columba livia domestica) (Grosch & Neuringer, 1981;Logue, Chavarro, Rachlin, & Reeder, 1988) and rats (Rattus norvegicus domesticus) (Reynolds, De Wit, & Richards, 2002). The outcome measure is typically at which point of delay subjects equally value the immediate and delayed reward (Stevens, Hallinan, et al., 2005). ...
Article
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Self‐control is critical for both humans and nonhuman animals because it underlies complex cognitive abilities, such as decision‐making and future planning, enabling goal‐directed behavior. For instance, it is positively associated with social competence and life success measures in humans. We present the first review of delay of gratification as a measure of self‐control in nonhuman primates, corvids (crow family) and psittacines (parrot order): disparate groups that show comparable advanced cognitive abilities and similar socio‐ecological factors. We compare delay of gratification performance and identify key issues and outstanding areas for future research, including finding the best measures and drivers of delayed gratification. Our review therefore contributes to our understanding of both delayed gratification as a measure of self‐control and of complex cognition in animals. This article is categorized under: • Cognitive Biology > Evolutionary Roots of Cognition • Psychology > Comparative Psychology Abstract Examples of delayed gratification tasks. (a) Exchange task with a corvid: subject can choose to swap a token (e.g., bottle top) for a reward after a delay; (b) Intertemporal choice: monkey can select the immediately available reward or wait for the delayed reward from a rotating tray.
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Under the remit of an expanded definition of sustainability – one that acknowledges animal agriculture as a key carbon intensive industry, and one that includes interspecies ethics as an integral part of social justice – institutions such as Universities can and should play a role in supporting a wider agenda for sustainable food practices on campus. By drawing out clear connections between sustainability objectives on campus and the shift away from animal based products, the objective of this article is to advocate for a more consistent understanding and implementation of sustainability measures as championed by university campuses at large. We will draw out clear connections between sustainability objectives on campus and the shift away from animal based products. Overall, our arguments are contextualised within broader debates on the relationship between sustainability, social justice and interspecies ethics. We envisage that such discussion will contribute to an enriched, more robust sense of sustainability—one in which food justice refers not only to justice for human consumers and producers of food and the land used by them, but also to justice for the nonhuman animals considered as potential sources of food themselves.
Article
Corvids possess cognitive skills, matching those of non-human primates. However, how these species with their small brains achieve such feats remains elusive. Recent studies suggest that cognitive capabilities could be based on the total numbers of telencephalic neurons. Here we extend this hypothesis further and posit that especially high neuron counts in associative pallial areas drive flexible, complex cognition. If true, avian species like corvids should specifically accumulate neurons in the avian associative areas meso- and nidopallium. To test the hypothesis, we analyzed the neuronal composition of telencephalic areas in corvids and non-corvids (chicken, pigeons, and ostriches - the species with the largest bird brain). The overall number of pallial neurons in corvids was much higher than in chicken and pigeons and comparable to those of ostriches. However, neuron numbers in the associative mesopallium and nidopallium were twice as high in corvids and, in correlation with these associative areas, the corvid subpallium also contained high neuron numbers. These findings support our hypothesis that large absolute numbers of associative pallial neurons contribute to cognitive flexibility and complexity and are key to explain why crows are smart. Since meso/nidopallial and subpallial areas scale jointly, it is conceivable that associative pallio-striatal loops play a similar role in executive decision-making as described in primates. This article is protected by copyright. All rights reserved
Article
A recent definition of animal welfare states that “the welfare of an animal is its positive mental and physical state related to the fulfilment of its physiological and behavioural needs in addition to its expectations. This state can vary depending on the animal’s perception of a given situation’. This definition confirms the importance of taking the individual animal perspective (i.e. its cognition) into consideration, in order to properly assess its welfare. Cognitive abilities of domestic chickens have been extensively studied in recent years, but few of these studies focussed on the relationship between chicken cognition and welfare issues commonly found in chicken production systems. Considering the chickens’ cognitive abilities offers new and different perspectives on the welfare problems faced by chicken production. Combined with applied research, cognitive studies can generate impactful and science- based strategies to solve these problems better. In this short non- systematic review, we focus on cognitive research aimed at understanding three widespread welfare issues in poultry production: uneven range use in free-range broiler chickens and laying hens, feather pecking in laying hens, and the unfulfilled behavioural and physiological needs of broiler breeders. Knowledge of chicken cognitive abilities is critical to ameliorate chickens’ rearing conditions and develop systems and practices that are more respectful of animal welfare.
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A parasitoid wasp has deposited half of her eggs in a host. She now faces the choice between depositing her remaining eggs in the same host or searching for another. Continuing to deposit in the current host provides the immediate payoff of completing her reproductive duties, allowing her to move on to other activities such as foraging or searching for another mate. Searching for another host, in contrast, delays the payoffs of reproducing until a suitable host is found. This wasp faces an intertemporal choice—that is, a choice between options that involve payoffs available at different times (Read, 2004; Stevens, 2010). These choices typically involve a smaller option available sooner and a larger option available later. In the wasp example, depositing all eggs in one host provides the smaller, sooner option because, though curtailing search sooner, increased offspring competition and risk of total failure reduces the overall benefit of this option. The larger, later option of continuing to search involves a time delay but yields a higher payoff with reduced competition and probability of total brood failure. In addition to reproductive decisions, animals make these choices on a daily basis when foraging, searching for a mate, seeking shelter, avoiding predators, and interacting with social partners (Stevens, 2010). Many aspects of life history theory provide examples of intertemporal choices. For instance, allocating energy toward reproduction or growth is a classic life history tradeoff that pits the smaller, sooner payoffs of reproducing now vs. the larger, later payoffs for growing and delaying reproduction. At this level of analysis, organisms without a central nervous system, such as plants and bacteria, make intertemporal choices (Kacelnik, 2003). Though not well researched outside of the animal kingdom, researchers have explored intertemporal choices in a wide range of animal species, including insects, fish, birds, rodents, dogs, and primates (Table 1). Comparative psychologists have investigated both why individuals should choose either the smaller, sooner or larger, later option via modeling approaches and how different psychological mechanisms regulate intertemporal choice.
Preprint
A recent definition of animal welfare states that "the welfare of an animal is its positive mental and physical state related to the fulfilment of its physiological and behavioural needs in addition to its expectations. This state can vary, depending on the animal's perception of a given situation". This definition confirms the importance of taking the individual animal perspective (i.e., its cognition) into consideration, in order to properly access its welfare. Cognitive abilities of domestic chickens have been extensively studied in recent years, but few of these studies focused on the relationship between chicken cognition and welfare issues commonly found on chicken production systems. Considering the chickens' cognitive abilities offer new and different perspectives on the welfare problems faced by chicken production. Combined with applied research, cognitive studies can generate impactful and science-based strategies to solve these problems better. In this short non-systematic review, we focus on cognitive research aimed at understanding three widespread welfare issues in poultry production: low range use in free-range broiler chickens and laying hens, feather pecking in laying hens, and the unfulfilled behavioural and physiological needs in broiler breeders. Knowledge of chicken cognitive abilities is critical to ameliorate chickens' rearing conditions and develop systems and practices that are more respectful of animal welfare.
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Animals need sufficient space to ensure physical health and to permit the performance of important behaviors. The effects of spatial restriction will increase with duration of confinement. In addition, diurnal rhythms are relevant. Animals may often require only sufficient space to rest comfortably but, at certain periods, additional space will be required for the performance of comfort, foraging, social or exploratory behavior. The spatial needs of unassuming animals such as chickens and rodents have been assessed using many approaches. First, animals can be housed at relevant allowances and a broad range of measures of health, behavior, physiological status and immune function taken to assess overall welfare. Second, the behavior of animals can be observed after spatial restriction is removed. A significant rebound in behavior performance would indicate that this behavior was being prevented by confinement. Third, the strength of animals' choices for additional space can be examined. Evidence from all three approaches showed that the extreme spatial confinement experienced by laying hens in conventional battery cages resulted in poor welfare, helping to secure a phase-out of conventional cages in Europe by 2012. It has been more difficult to establish optimum space allowances for species kept under less extreme restriction, such as laboratory mice and rats. No consistent effects on welfare were found when inbred and outbred mice were housed at 60, 100 or 167 cm2/mouse. In contrast, sleep disruption was increased when young rats housed were housed at higher stocking densities. Finally, assessment of optimum spatial allowance (stocking density) for animals housed in large groups, is complicated by complex interactions between enclosure size and group number.
Article
In order to face a constantly changing environment, animals need to be able to update their knowledge of the world on the basis of new information. Often, this means to inhibit a previously acquired response and flexibly change their behaviour to produce a new response. Here, we measured such abilities in young domestic chicks, employing a Colour Reversal Learning Task. During the acquisition phase, 17 one-week-old male chicks had to learn to peck on one of two coloured boxes to obtain a food reward. After reaching criterion, chicks underwent a reversal phase in which the previously learned colour-reward contingency was swapped. As expected from the literature, chicks performed better in the acquisition phase with respect to the reversal phase. Results moreover highlighted the presence of a lateralized bias selectively during reversal: chicks performed better if the stimulus rewarded was located in the left hemispace (processed by the right hemisphere). Interestingly, the bias correlated with the individual difficulty, i.e., it was stronger in those chicks which needed more trials to complete the reversal session. The present study contributes evidence in support of behavioural flexibility in young chicks, along with a novel perspective on lateralized mechanisms that might underlie such ability.
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This study aimed to identify hungry broiler breeders (n = 12) preferences for quantitative (control) or qualitative dietary restriction (QDR) in a closed economy environment. The QDR option was either 3 g calcium propionate/kg total feed (n = 6) or 300 g oat hulls/kg total feed (n = 6). Quantitatively restricted or QDR portions ensured equal growth regardless of choice. Birds were separately taught a Control diet versus no food and a QDR diet versus no food task to allow each diet's satiating properties to be learnt. Birds had to associate the T-maze coloured arms with dietary outcomes to immediately obtain food. Birds learnt this task easily (p < 0.001). A choice between the control diet and the QDR diet was then offered but neither group demonstrated a diet preference. Study modifications demonstrated this was not a failure to discriminate between the diets per se (the Control diet was strongly preferred under ad libitum conditions (p < 0.001)) or novel colour combination confusion (the colour associated with food was immediately selected when two novel food versus no food colour combinations were offered (p < 0.001)). Most birds still failed to show a significant preference when the Control diet quantity was increased by 50% to make it 'obviously' bigger and better. Therefore, it was concluded that the failure to show a dietary preference was due to task learning failure and not necessarily lack of dietary preference. Where a preference was observed it was always for the control diet. Possible reasons for this failure to learn are discussed. (C) 2011 Elsevier B.V. All rights reserved
Article
This is an uncorrected author's draft of a paper published in The Monist issue on neuroethics, Volume 95, Issue 3 (July 2012). For citation and quoting purposes, please use the published version.Recent work in moral theory has seen the refinement of theories of moral standing, which increasingly recognize a position of intermediate standing between fully self-conscious entities and those which are merely conscious. Among the most sophisticated concepts now used to denote such intermediate standing is that of primitive self-consciousness, which has been used to more precisely elucidate the moral standing of human newborns. New research into the structure of the avian brain offers a revised view of the cognitive abilities of birds. When this research is approached with a species-specific focus, it appears likely that one familiar species, the chicken (Gallus gallus domesticus), also exhibits primitive self-consciousness. Given the likelihood that they are primitively self-consciousness, chickens warrant a degree of moral standing that falls short of that enjoyed by persons, but which exceeds the minimal standing of merely conscious entities.
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Previous studies have shown that domestic chicks, Gallus gallus domesticus, trained in a competitive foraging condition would subsequently develop a high degree of impulsiveness in an intertemporal choice paradigm. Competition inevitably causes variance in the amount of food that the foragers gain. However, it is not known whether the food variance is causally linked with the impulsiveness. In experiment 1, we compared four groups of chicks trained in combinations of two social conditions (pseudocompetition or isolated) and two food conditions (variable or constant food). The food variance was introduced by varying the number of grains in each trial according to a binomial distribution. The subject chick was separated from the competitors by a transparent wall, and no actual interference occurred. Chicks were subsequently tested in binary choices between a small reward after a short delay (SS) and a large reward after a long delay (LL) in an isolated and constant food condition. If chicks had been trained under the pseudocompetition and variable food, they chose LL significantly less frequently than the other three groups. The effect disappeared when the LL delay was omitted, suggesting that chicks accurately memorized the food amount. The food variance is thus a necessary condition for the stronger temporal discounting. Otherwise, the observed effect could be ascribed to a paradoxical risk proneness associated with the variable option. In experiment 2, we compared four groups of chicks in which food amount varied either in SS or LL, or both. The subsequent binary choice tests revealed that the chicks chose SS irrespective of whether SS or LL had varied. These results cannot be explained in terms of a greater risk-prone choice of the variable option. Coincidence of perceived competition and food variance, at least in one option, is sufficient for chicks to develop choice impulsiveness.
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I sketch briefly some of the more influential theories concerned with the moral status of nonhuman animals, highlighting their biological/physiological aspects. I then survey the most prominent empirical research on the physiological and cognitive capacities of nonhuman animals, focusing primarily on sentience, but looking also at a few other morally relevant capacities such as self-awareness, memory, and mindreading. Lastly, I discuss two examples of current animal welfare policy, namely, animals used in industrialized food production and in scientific research. I argue that even the most progressive current welfare policies lag behind, are ignorant of, or arbitrarily disregard the science on sentience and cognition.
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While it is well established that humans respond to inequity, it remains unclear the extent to which this behavior occurs in our non-human primate relatives. By comparing a variety of species, spanning from New World and Old World monkeys to great apes, scientists can begin to answer questions about how the response to inequity evolved, what the function of this response is, and why and how different contexts shape it. In particular, research across non-human primate species suggests that the response is quite variable across species, contexts, and individuals. In this paper, we aim to review these differences in an attempt to identify and better understand the patterns that emerge from the existing data with the goal of developing directions for future research. To begin, we address the importance of considering socio-ecological factors in non-human primates in order to better understand and predict expected patterns of cooperation and aversion to inequity in different species, following which we provide a detailed analysis of the patterns uncovered by these comparisons. Ultimately, we use this synthesis to propose new ideas for research to better understand this response and, hence, the evolution of our own responses to inequity.
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Self-control, that is, overcoming impulsivity towards immediate gratification in favour of a greater but delayed reward, is seen as a valuable skill when making future-oriented decisions. Experimental studies in nonhuman primates revealed that individuals of some species are willing to tolerate delays of up to several minutes in order to gain food of a higher quantity or quality. Recently, birds (carrion crows, Corvus corone, common ravens, Corvus corax, Goffin cockatoos, Cacatua goffiniana) performed comparably to primates in an exchange task, contradicting previous notions that birds may lack any impulse control. However, performance differed strikingly with the currency of exchange: individuals of all three species performed better when asked to wait for a higher food quality, rather than quantity. Here, we built on this work and tested whether the apparent difference in levels of self-control expressed in quality versus quantity tasks reflects cognitive constraints or is merely due to methodological limitations. In addition to the exchange paradigm, we applied another established delay maintenance methodology: the accumulation task. In this latter task, food items accumulated to a maximum of four pieces, whereas in the exchange task, an initial item could be exchanged for a reward item after a certain time delay elapsed. In both tasks, birds (seven crows, five ravens) were asked to wait in order to optimize either the quality or the quantity of food. We found that corvids were willing to delay gratification when it led to a food reward of higher quality, but not when waiting was rewarded with a higher quantity, independent of the experimental paradigm. This study is the first to test crows and ravens with two different paradigms, the accumulation and the exchange of food, within the same experiment, allowing for fair comparisons between methods and species.
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The concept of “liberty” has been revised in great depth by multiple authors of a great variety of disciplines. However, only at the beginning of the XIX century that the modern evolutionary theory opens the possibility of studying it as an evolutionary capacity and a cognitive process. Is it then possible to identify its components in other species by understanding its behavioural or cognitive correlates, as it is often attempted for other complex phenomena (“empathy”, “love”, “intelligence”, etc.) that are similarly based on the interaction of a variety of processes at different levels of organization? Based on empirical evidence, this work analyses the degree by which three necessary components (while probably insufficient) of the de faculty referred to as “liberty” can be found in non-human organisms: (i) the degree of behavioural flexibility, (ii) the capacity for voluntary behavioural restriction and (iii) the capacity for recognition of responsibility.
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It does not just advertise what the author thinks we know about chicken behavioural biology but actually lays out the evidence… Of tremendous value to all students of poultry science, animal behaviour and animal welfare in general… A masterpiece in the communication of science.' Professor Dr. Hanno Würbel, University of Bern, Switzerland. Chickens are by far the world's most widely farmed animal, kept for both meat and egg production. They are at the centre of debates regarding housing and production systems, fuelling significant interest in what explains and influences chicken behaviour. Authored by an authority on chicken ethology, this book: • covers topics important to chicken welfare, such as sensory biology, behavioural development, preferences and aversions, social behaviour, learning and cognition; • addresses behavioural problems across different systems and provides solutions to improve the lives of farmed chickens around the world; and • brings together the diverse fields of animal behaviour, neuroscience, psychology and epidemiology to provide a comprehensive understanding of chicken behaviour. Practical and accessible, this book forms an essential resource in chicken biology and behaviour for students of veterinary science, behaviour and welfare, as well as commercial poultry producers and smallholder farmers wanting to improve their chickens' quality of life.
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The aim of the book is to ground the logical origins of consciousness in what I have previously called the ‘minimal self’. The idea is that elementary forms of consciousness are logically dependent not, as is commonly assumed, on ownership of an anatomical brain or nervous system, but on the intrinsic reflexivity that defines minimal selfhood. The book seeks to trace the logical pathway by which minimal selfhood gives rise to the possible appearance of consciousness. It is argued that in specific circumstances it thus makes sense to ascribe elementary consciousness to certain predatory single-celled organisms such as amoebae and dinoflagellates as well as to some of the simpler animals. Such an argument involves establishing exactly what those specific circumstances are and determining how elementary consciousness differs in nature and scope from its more complex manifestations.
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A surge of interest in cognitive science has revealed unexpectedly impressive cognitive abilities in many species, including many farmed animals such as salmon, cows, and chickens. Along with these discoveries, animal welfare scientists have uncovered evidence suggesting that animals are motivated to exercise their cognitive skills and may suffer when prevented from doing so. Moreover, environments that tend to produce good welfare also tend to improve cognitive capacity, and yet, conversely, certain stressful experiences can actually enhance aspects of cognitive function. Beyond influencing cognitive ability, research has shown that good welfare also involves characteristic cognitive propensities—the motivation to seek out new information as well as the tendency to process ambiguous information positively (optimistically) vs. negatively (pessimistically). How can we make sense of these complex patterns? This chapter covers the ways in which cognition—mental actions related to the processing of information—is simultaneously a cause, consequence, and component of welfare. Further disentangling the cognition-welfare relationship promises to lead to novel scientific discoveries and will help us to continue to improve the lives of the animals under our care.
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The burgeoning literature on numerical skills, counting and quantity judgements by animals over the past two decades attests that the long shadow of Clever Hans has finally dissipated. Not only have the types of tasks expanded, but the number of species, particularly those outside the mammalian order, is beginning to become more diverse. The primate order has been well represented, including studies with capuchin monkeys (Judge, Evans and Vyas, 2005), cotton-top tamarins (Uller, Hauser and Carey, 2001), rhesus monkeys (Beran, 2001, 2007a, b; Brannon and Terrace, 1998; Cantlon and Brannon, 2006; Hauser, Carey and Hauser, 2000); squirrel monkeys (Thomas and Chase, 1980; Terrell and Thomas, 1990), chimpanzees (Beran and Beran, 2004; Beran, Evans and Harris, 2008; Biro and Matsuzawa, 2001; Boysen and Berntson, 1989; Matsuzawa, 1984; Tomanaga, 2008), gorillas (Hanus and Call, 2007) and orang-utans (Call, 2000). However, some of the most interesting new studies have explored numerical questions with such disparate species as salamanders (Uller et al., 2003), chickens (Abeyesinghe et al., 2005), parrots (Pepperberg, 1994; Vick and Bouvet, in press), horses (Uller and Lewis, 2009), pigeons (Emmerton, Lohmann and Neimann, 1997; Roberts, 2005), mangabey monkeys (Albaich-Serrano, Guillen-Salazar and Call, 2007), cotton-top tamarins (Kralik, 2005), dolphins (Kilian et al., 2003), dogs (West and Young, 2002), sea lions (Gentry and Roeder, 2006; Gentry, Palmier and Roeder, 2004), cleaner wrasse fish (Danisman, Bshary and Bergmüller, 2010) and mosquitofish (Agrillo, Dadda and Bisazza, 2007).
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This paper reviews the literature on human attitudes to animals, and postulates the existence of two primary motivational determinants of attitudes labelled 'affect' and 'utility'. It also proposes that the relative strengths of these key attitude dimensions are affected by various modifying variables including the specific attributes of the animal, the individual characteristics and experience of the person evaluating the animal, and a range of cultural factors. The role of science as a cultural modifier of human attitudes to animals is also discussed.
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Results from the operant laboratory suggest that short-term benefits guide animal feeding decisions. These results appear to contradict evolutionarily-motivated models of foraging that emphasize long-term benefits. Because of this contradiction, some behavioral ecologists argue that natural selection must favor short-term benefits in some unknown way. This study addresses the contradiction by testing the feeding preferences of captive blue jays in two economically equivalent situations. The first situation follows the operant literature' s "self- control" paradigm; jays make a binary choice between small-immediate and large-delayed options. The second situation is modeled on patch-use problems; the jays make a leave-stay decision in which "leaving" leads to small amount in a short time, and "staying" leads to larger amount in a longer time. In the self-control situations, the observed outcome agrees with short-term rate maximizing, as other investigators have reported. In the patch situation, the results agree more closely with long-term rate maximizing. The text explains how a rule of preference based on short-term rate comparisons can account for both situations. It is argued that natural selection may have favored short-term rules because they have long-term consequences in many natural foraging situations.
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Behavioural adaptations to resource variability were examined in field experiments with least chipmunks, Tamias minimus, and golden-mantled ground squirrels, Spermophilus lateralis. Artificial patches of unhulled sunflower seeds were held stable or varied in quality. The rate at which the unstable patches changed and the length of time elapsing before animals could choose between them were systematically varied. When their foraging information grew older and lost its reliability, the animals depended less on recent experience and more on patch averages in making their choices. The rate at which the transition occurred was related to the rate of patch change. These adaptations were predicted by a dynamic patch assessment model that weights patch information according to its reliability.
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This paper concerns the response of foraging animals to variability in rate of gain, or risk. Both the empirical and theoretical literatures relevant to this issue are reviewed. The methodology and results from fifty-nine studies in which animals are required to choose between foraging options differing in the variances in the rate of gain available are tabulated. We found that when risk is generated by variability in the amount of reward, animals are most frequently risk-averse and sometimes indifferent to risk, although in some studies preference depends on energy budget. In contrast, when variability is in delay to reward, animals are universally risk-prone. A range of functional, descriptive and mechanistic accounts for these findings is described, none of which alone is capable of accommodating all aspects of the data. Risk-sensitive foraging theory provides the only currently available explanation for why energy budget should affect preference. An information-processing model that incorporates Weber's law provides the only general explanation for why animals should be risk-averse with variability in amount and risk-prone with delay. A theory based on the mechanisms of associative learning explains quantitative aspects of risk-proneness for delay; specifically why the delay between choice and reward should have a stronger impact on preference than delays between the reward and subsequent choice. It also explains why animals should appear to commit the "fallacy of the average," maximising the expected ratio of amount of reward over delay to reward when computing rates rather than the ratio of expected amount over expected delay. We conclude that only a fusion of functional and mechanistic thinking will lead to progress in the understanding of animal decision making.
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Foraging currencies based on average rates of energy gain often fail to predict observed behaviour when an animal must choose between a smaller, more immediate reward and a larger, more delayed reward. We review experiments demonstrating that a forager's choice may depend on the ratio of reward sizes, the difference in pursuit times, and the magnitude of the average pursuit time. The most telling result is that of Green et al. (1981), who showed that foragers prefer the smaller, more immediate reward when both pursuit times are relatively small, but they prefer the larger, more delayed reward when both pursuit times are relatively large. This paper proposes a new theoretical explanation by modifying a standard economic model for discounting future rewards. Our model of a variable time bias specification can explain the observed, temporally inconsistent preferences. Discounting future rewards might be an adaptive response to uncertainty in an animal's natural environment, but we cannot reject the possibility that preference for immediacy is a behavioural constraint on foraging efficiency.
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Although there may be task-specific differences in performance between wild and domestic animals, there is no evidence for any generally reduced cognitive capacity in domestic animals. It is not possible to compare intelligence between species or breeds without recognizing the contribution of differences in attention and motivation, and domestic animals often perform better on learning tasks than wild animals because they are less fearful. Considerable flexibility and complexity in behaviour can arise from context-specific decisions that may not require learning. Examples include alarm calling and maternal behaviour in chickens. However, the majority of intelligent behaviour shown by farm animals is dominated by learned associations, sometimes in response to remarkably subtle cues. Seemingly straightforward learning abilities may result in surprising emergent properties. An understanding of these properties may enable us to investigate how farm animals interact socially, and whether they form concepts. Other abilities, such as imitation and the re-organization of spatial information, do not appear to depend on associative learning. The study offarm animal cognition tells us little about the issue of animal consciousness but, none the less, plays an important role in the animal welfare debate. The types of cognitive abilities animals have provide clues as to the types of situations in which (given the benefit of the doubt) they might suffer.
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Delay between choice and receipt of reinforcement (prereinforcer delay) and delay between receipt of reinforcement and the next opportunity to choose (postreinforcer delay) were varied in a discretetrials choice paradigm using four pigeons. The pigeons consistently chose the reinforcer with the smaller prereinforcer delay. Variations in postreinforcer delay did not affect choice unless prereinforcer delays were equal. The results support previous findings that prereinforcer delays contribute disproportionately to the effects of rate of reinforcer access on choice in pigeons.
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Five rats served as subjects in an experiment that examined the effect of increasing response effort on self-control (choice of a larger, more delayed reinforcer over a smaller, less delayed reinforcer). The rats made significantly more self-control choices as the force required to respond on each lever increased from 0.1 to 0.8 N. As the force required to press the levers increased to 1 N and then began to decrease, some of the rats stopped responding. For those rats that continued to respond, self-control tended to decrease. The results suggest that increasing the required response force can increase selfcontrol choices, as long as the required response force is low enough that some responding occurs.
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Two experiments tested two cynomolgus monkeys’ self-control—choice of a longer, more delayed reinforcer over a shorter, less delayed reinforcer. In Experiment 1, subjects exhibited significant selfcontrol in a procedure in which reinforcer amounts and delays were held constant throughout a condition. In Experiment 2, subjects exhibited significantly greater sensitivity to variation in reinforcer amount than to variation in reinforcer delay in a procedure in which the reinforcer delay associated with the self-control alternative was adjusted until each macaque was indifferent between the two alternatives. Both experiments indicated that, in laboratory paradigms in which humans show self-control and pigeons and rats show impulsiveness, macaques show self-control. These results are inconsistent with the hypothesis that species differences in self-control are a function of language ability or of specific types of prior training. The results are consistent with the hypothesis that species differences in self-control are related to the ratio of brain size to body weight (a possible indicator of general cognitive ability) or to shared phylogeny.
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Pigeons’ choices between larger, more delayed and smaller, less delayed reinforcers were examined while the pigeons lived in the experimental chamber for 23-h sessions. In Condition 1, 4 pigeons were food deprived prior to each session and exposed to one session every 4th day. Condition 2 was identical except that the pigeons began each session at their ad-lib weights. Condition 3 was identical to Condition 2 except that sessions were conducted on consecutive days. Condition 4 was identical to Condition 3 except that the subjects (2 pigeons from Conditions 1–3 plus a naive pigeon) could obtain reinforcers much less frequently. In all of the conditions, the pigeons consistently chose the smaller, less delayed reinforcers; the pigeons were impulsive. The restriction of food access caused a disruption in the diurnal pattern of feeding, but did not decrease impulsiveness even in this 23-h live-in procedure.
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What is time? St. Augustine knew: “I know what time is”, he said, “but if someone asks me, I cannot tell him” (Landes, 1983, p. 1). Not much help. It is the business of scientists to tell, and another ancient philosopher tells us how to tell: Aristotle sought to understand phenomena—and communicate that knowledge— by identifying their four "[be]causes", which he called material, final, efficient, and formal. We have interpreted these as questions about what (description/definition and substrate), why (function), how (mechanism), and like (analogs and models). These four causes organize our analysis of time and timing.
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In general, codes that have been designed to safeguard the welfare of animals emphasize the importance of providing an environment that will ensure good health and a normal physiological and physical state, that is, they emphasize the animals' physical needs. If mental needs are mentioned, they are always relegated to secondary importance. The argument is put forward here that animal welfare is dependent solely on the cognitive needs of the animals concerned. In general, if these cognitive needs are met, they will protect the animals' physical needs. It is contended that in the few cases in which they do not safeguard the physical needs, it does not matter from a welfare point of view. The human example is given of being ill. It is argued that welfare is only adversely affected when a person feels ill, knows that he or she is ill, or even thinks that he or she is ill, all of which processes are cognitive ones. The implications for welfare of animals possessing certain cognitive abilities are discussed. For example, the extent to which animals are aware of their internal state while performing behavior known to be indicative of so-called states of suffering, such as fear, frustration, and pain, will determine how much they are actually suffering. With careful experimentation it may be possible to determine how negative they feel these states to be. Similarly, the extent to which animals think about items or events absent from their immediate environment will determine how frustrated they are in the absence of the real item or event but in the presence of the cognitive representation.
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We base a theory of timing on the observation that signals of reinforcement elicit adjunctive behaviors. The transitions between these behaviors are well described as a Poisson process, with a rate constant proportional to the rate of reinforcement in the experimental context. These behaviors may come to serve as the basis for conditional discriminations of the passage of time. Varying the rate of reinforcement will generate distributions of behavior whose mean and standard deviation vary proportionately. Holding the rate of reinforcement constant while manipulating the intervals to be judged will generate different functional relations between the mean and standard deviation, and these will lead to bisection at or slightly above the geometric mean, depending on the measure of bisection employed. The correlation between the rate of the Poisson process and the rate of reinforcement implies that psychometric functions should be affected by the rate of reinforcement. This prediction is confirmed. We extend the models derived from this theory to other phenomena, such as temporal generalization and discrimination, subjective shortening, and paired comparisons of intervals. Current models of choice between delayed reinforcers are consistent with our theory of timing. (PsycINFO Database Record (c) 2012 APA, all rights reserved)
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Eight pigeons chose between a small, immediate reinforcer and a large, increasingly delayed reinforcer. Responding during the large-reinforcer delays was examined. During large-reinforcer delays, pecks on one key produced the small, immediate reinforcer; pecks on the other key had no effect. Thus, a pigeon could reverse its initial choice of the large, delayed reinforcer, or it could maintain its original choice. Pigeons that made a relatively high number of initial large-reinforcer choices tended to maintain these choices, and those pigeons that actually received a relatively high number of large reinforcers, tended to respond more frequently on the ineffective key during the delay periods. The findings suggest that some previous studies of self-control training in pigeons may have resulted in increased self-control partially due to a lack of opportunity for the pigeons to change their choices.
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A 2-system framework is proposed for understanding the processes that enable--and undermine--self-control or "willpower" as exemplified in the delay of gratification paradigm. A cool, cognitive "know" system and a hot, emotional "go" system are postulated. The cool system is cognitive, emotionally neutral, contemplative, flexible, integrated, coherent, spatiotemporal, slow, episodic, and strategic. It is the seat of self-regulation and self-control. The hot system is the basis of emotionality, fears as well as passions--impulsive and reflexive--initially controlled by innate releasing stimuli (and, thus, literally under "stimulus control"): it is fundamental for emotional (classical) conditioning and undermines efforts at self-control. The balance between the hot and cool systems is determined by stress, developmental level, and the individual's self-regulatory dynamics. The interactions between these systems allow explanation of findings on willpower from 3 decades of research.
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Self-control means choosing a large delayed reward over a small immediate reward; impulsiveness is its opposite. The metabolic hypothesis states that the amount of self-control across species correlates negatively with metabolic rate (Tobin & Logue, 1994). Foraging honeybees have high metabolic rates; the metabolic hypothesis would predict little self-control in bees. But foraging bees work for the long-term good of their hive, conditions that seem to require self-control. In three experiments, we gave bees the choice between (1) a sweeter delayed reward and a less sweet immediate reward and (2) a large delayed reward and a small immediate reward. Bees showed much self-control, inconsistent with the metabolic hypothesis.
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Effects of bilateral chemical lesions of the medial basal ganglia [lobus parolfactorius (LPO)] were examined in 7- to 14-d-old domestic chicks. Chicks were trained in a color discrimination task, in which the subject had to peck one of the two colored beads associated with rewards that differed in quantity (amount of food) and/or temporal proximity (delay of food delivery from peck). In experiment 1, food was given without delay, and chicks successfully learned to choose a colored bead that was associated with a larger reward than the other. In experiment 2, a colored bead (red) was associated with a large reward delivered after a delay (D = 1, 2, or 3 sec), whereas another (yellow) was associated with a small reward delivered immediately. In intact and sham-operated conditions, chicks with a longer D chose the red bead progressively fewer times. Selective lesions to the caudal LPO (but not the rostral LPO) caused impulsive choice, and the ablated chicks chose the yellow bead and gained a small-immediate reward regardless of D. However, when retrained in a null-delay condition (D = 0 sec), the lesioned chick chose the red bead again. Ability to associate novel colors with reward was also unimpaired. These results suggest that the LPO may be responsible for the anticipation of reward proximity and involved in a suppression of impulsiveness by which animals seek immediate gains. The present results also indicate a striking similarity in functional roles between the avian LPO and the nucleus accumbens/ventral striatum in mammals.
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People can time travel cognitively because they can remember events having occurred at particular times in the past (episodic memory) and because they can anticipate new events occurring at particular times in the future. The ability to assign points in time to events arises from human development of a sense of time and its accompanying time-keeping technology. The hypothesis is advanced that animals are cognitively stuck in time; that is, they have no sense of time and thus have no episodic memory or ability to anticipate long-range future events. Research on animals' abilities to detect time of day, track short time intervals, remember the order of a sequence of events, and anticipate future events are considered, and it is concluded that the stuck-in-time hypothesis is largely supported by the current evidence.
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The assumption that animals are conscious and capable of experiencing negative sensations and emotions is at the core of most people's concerns about animal welfare. Investigation of this central assumption should be one goal of animal welfare science. We argue that theory and techniques from cognitive science offer promising ways forward. Evidence for the existence of conscious and non-conscious cognitive processing in humans has inspired scientists to search for comparable processes in animals. In studies of metacognition and blindsight, some species show behaviour that has functional parallels with human conscious cognitive processing. Although unable to definitively answer the question of whether the animals are conscious, these studies provide fresh insights, and some could be adapted for domestic animals. They mark a departure from the search for cognitive complexity as an indicator of consciousness, which is based on questionable assumptions linking the two. Accurate assessment of animal emotion is crucial in animal welfare research, and cognitive science offers novel approaches that address some limitations of current measures. Knowledge of the relationship between cognition and emotion in humans generates a priori frameworks for interpreting traditional physiological and behavioural indicators of animal emotion, and provides new measures (eg cognitive bias) that gauge positive as well as negative emotions. Conditioning paradigms can be used to enable animals to indicate their emotional state through operant responses. Although evidence for animal consciousness and emotion will necessarily be indirect, insights from cognitive science promise further advances in our understanding of this fundamentally important area in animal welfare science.
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Psychological studies of animal choice show that the immediate consequences of choice strongly influence preference. In contrast, evolutionary models emphasize the longer-term fitness consequences of choice. Building on recent work by Stephens & Anderson (2001, Behavioral Ecology12, 330–339), this study presents two experiments that address this conflict. Stephens & Anderson developed an alternative choice situation based on patch-leaving decisions and compared this to the binary choice, or self-control, situation typically used in psychological studies. They hypothesized that the same short-term choice rule could account for choice in both situations, maximizing long-term gains in the patch situation, but typically producing shortsighted results in the self-control case. Experiment 1 used captive blue jays, Cyanocitta cristata, to test this ‘same rule’ hypothesis. The results do not support this hypothesis, suggesting that if a single rule applies, it is probably a more complex rule. Stephens & Anderson also hypothesized that a rule based on the delay to the next meal could explain why the intertrial interval has little effect in binary choice studies, even though the analogous travel time strongly affects patch-leaving decisions. When an animal leaves a patch, it experiences a delay consisting of the travel time plus time spent searching in the patch until food is obtained. Experiment 2 tested the hypothesis that travel time and search time combine additively, behaving like a single delay. Using treatments that created the same combined delay via different combinations of travel and search time, we found no evidence of nonadditivity, suggesting that these two components may indeed be treated as a single delay. Copyright 2003 Published by Elsevier Ltd on behalf of The Association for the Study of Animal Behaviour.
Article
This chapter interprets Aristotle's four causes, which he called material, final, efficient, and formal as questions about what (description/ definition and substrate), why (function), how (mechanism), and like (analogs and models). These four causes organize the analysis of time and timing. Time is not a fourth dimension—although it may be measured on one. It is not itself a cause—even though effects unfold in time. Time was not discovered; it was invented. The conceptions of time that have been invented by physicists have been adopted by society at large, so that there is a good correlation between the physicist's time— SI time—and that on our clocks—Big Ben Time. Both times are measured on cyclic interval scales. An animal is only said to be timing while it is involved in activities that in the past have been reinforced for improving temporal judgments.
Article
Psychological studies of animal choice show that the immediate consequences of choice strongly influence preference. In contrast, evolutionary models emphasize the longer-term fitness consequences of choice. Building on recent work by Stephens & Anderson (2001, Behavioral Ecology12, 330–339), this study presents two experiments that address this conflict. Stephens & Anderson developed an alternative choice situation based on patch-leaving decisions and compared this to the binary choice, or self-control, situation typically used in psychological studies. They hypothesized that the same short-term choice rule could account for choice in both situations, maximizing long-term gains in the patch situation, but typically producing shortsighted results in the self-control case. Experiment 1 used captive blue jays, Cyanocitta cristata, to test this ‘same rule’ hypothesis. The results do not support this hypothesis, suggesting that if a single rule applies, it is probably a more complex rule. Stephens & Anderson also hypothesized that a rule based on the delay to the next meal could explain why the intertrial interval has little effect in binary choice studies, even though the analogous travel time strongly affects patch-leaving decisions. When an animal leaves a patch, it experiences a delay consisting of the travel time plus time spent searching in the patch until food is obtained. Experiment 2 tested the hypothesis that travel time and search time combine additively, behaving like a single delay. Using treatments that created the same combined delay via different combinations of travel and search time, we found no evidence of nonadditivity, suggesting that these two components may indeed be treated as a single delay. Copyright 2003 Published by Elsevier Ltd on behalf of The Association for the Study of Animal Behaviour.
Article
The way in which cognitive functioning is affected by stressors is an important area of research for applied ethologists because stress caused by captive conditions may disrupt cognitive processes and lead to welfare and husbandry problems. Such problems may be minimised through an understanding of the links between stress and cognition. The effects of stress on cognitive function have been studied in disciplines ranging from human perceptual psychology to animal neuroscience. The aim of this paper is to provide an introduction to this research, focusing on the effects of stressors on attention, memory formation and memory recall. Findings from such a diverse literature with little apparent inter-disciplinary communication are inevitably complex and often contradictory. Nevertheless, some generalities do emerge. The idea that an inverted U-shaped relationship exists between an individual's state of stress or arousal and its ability to perform a cognitive task effectively, the so-called Yerkes–Dodson law, is commonly encountered. The law has limited explanatory value because it is unlikely that different stressors act on cognitive function via the same intervening, non-specific state. Furthermore, the law only provides a very general description of the relationship between stress and cognitive function. Empirical research on attention and memory processes reveals more specific findings. Stressors appear to cause shifts, lapses and narrowing of attention, and can also influence decision speed. These processes may be viewed as serving an adaptive role helping the animal to search for and scrutinise a source of danger. There is conflicting evidence as to whether hormones involved in the hypothalamic–pituitary–adrenal stress response play a part in these processes. These hormones and those involved in the sympathetic-adrenomedullary stress response do appear to play an important role in memory formation. Low or moderate concentrations of circulating glucocorticoids and catecholamines can enhance memory formation, while excessively high or prolonged elevations of these hormones can lead to memory disruption. The effects of stressors on memory recall are less clear. There is evidence for disruptive effects, and for facilitatory effects indicating state-dependent memory recall; events experienced under conditions of high arousal may be best recalled under similar conditions. Applied ethologists have the opportunity to extend work in this area, which often involves studies of single stressors/stress hormones acting in isolation and limited measures of cognitive function, by focusing on real-life husbandry stressors encountered by captive animals. This will yield fundamental information which also has direct relevance to animal welfare and management issues.
Article
This experiment investigated the ability of the domestic hen to predict a time interval of several minutes when given a reliable signal. This was achieved using the peak procedure method, an extension of a fixed interval (FI) schedule that gives partial reinforcement to identify temporal expectation on both sides of a remembered time for food delivery. Five birds were individually trained to peck a computer controlled touch screen. The screen displayed a symbol to signal the start of a trial and the first peck to the symbol after the FI of 6min had elapsed resulted in food being provided, the houselight in the roof of the pen illuminating, and the screen going blank. On probe trials the hens were not rewarded and the trial continued for 9min. The birds obtained on average 90% of available rewards on non-probe trials. On probe trials the response rate increased gradually reaching a maximum around the time of expected reinforcement of 6min. The birds showed a lowered level of response at the start of the interval. The percentage of the FI that had elapsed before 25% of the responses had occurred was consistently greater than 25%. The results indicate that domestic hens may have the ability to estimate the time to reward when given a reliable visual signal several minutes in advance.
Article
A preference test was used to demonstrate that gilts have the ability to associate two sets of neutral cues with two different periods of confinement and water deprivation and to anticipate the long-term consequences of their choice in the test. Twelve gilts housed in two large, straw-bedded pens were trained to go to two sets of 12 crates, positioned on each side of a choice point, for feeding twice a day. Following initial training, the two sets of crates were marked with contrasting visual patterns and the patterns were associated with either 30 min (‘short' confinement) or 240 min (‘long' confinement) of confinement in the crates after entry. During 16 days of preference testing, the gilts were sent alternately to one side or the other in the mornings and allowed to choose in the afternoons. Eight gilts chose the short confinement side more often, two, the long confinement side more often and two, each side an equal number of times, indicating that most gilts learned the association and preferred to be released shortly after feeding. However, gilts still chose the long confinement side on occasion, suggesting that they did not find 240 min of confinement very aversive. When the gilts were sent to the crates in the morning, their behaviour indicated that they expected to be released or confined depending on which crate they were in. The cognitive abilities of animals with respect to perception of time and anticipation of future events have important implications for their welfare. This study demonstrates that methods can be developed to ask animals about such things.
Article
Thinking about animal consciousness is beset with many pitfalls, a few of which are: i) lack of clarity in words used, especially confusing 'cognition' with 'consciousness' and using words such as 'emotion' in both an objective sense (behaviour and physiology) and to imply consciousness; ii) failing to acknowledge sufficiently that different people use different versions of the argument from analogy with ourselves to infer consciousness in non-humans in animals; iii) assuming that choice and preference imply consciousness; iv) assuming that autonomic responses imply consciousness (a particular danger to those who look for physiological 'measures' of animal welfare); v) assuming that complexity of behaviour implies complexity of cognition and in turn consciousness; and vi) assuming that only cognitively complex organisms are conscious. Consciousness raises many questions of direct relevance to animal welfare that as yet have no answers, but finding possible answers may be made slightly easier if we avoid these obvious pitfalls.
Article
In humans, psychological manipulations such as hypnosis, behavioural modifications, relaxation training and cognitive behaviour therapy have all been used to reduce pain intensity. One thing these treatments have in common is selective attention. Work on attention-based cognitive coping strategies has shown that they have potentially useful analgesic qualities in pain therapy. In animals, there have been few studies on the effects of attentional shifts on pain perception. There is extensive literature on stress-induced analgesia and it is likely that, in some of the experiments, attention could be an important variable. This paper will present some of our recent work on selective attention and pain perception using the sodium urate model of gouty arthritis. Birds are naturally prone to articular gout and the model we have developed mimics acute gouty attacks in a single joint. Experimental sodium urate arthritis produces a tonically painful inflammation lasting for at least 3h during which time the animals show pain-related behaviours. Changes in motivation can reduce these pain-related behaviours and it has been hypothesized that these motivational changes act by way of altering the attention of the animal away from pain. The motivational changes investigated included nesting, feeding, exploration and social interactions. The degree of pain suppression ranged from marked hypoalgesia to complete analgesia and as such demonstrates a remarkable ability to suppress tonic pain. These shifts in attention not only reduced pain but also significantly reduced peripheral inflammation. These results are discussed in terms of the limited capacity models of attention.
Article
Anthropocentric claims about the ways in which non-human animals interact in their social and non-social worlds are often used to influence decisions on how animals can or should be used by humans in various sorts of activities. Thus, the treatment of individuals is often tightly linked to how they are perceived with respect to their ability to perform behavior patterns that suggest that they can think—have beliefs, desires, or make plans and have expectations about the future. This article reviews some basic issues in the comparative study of animal minds and discusses how matters of mind are related to matters of welfare and well-being. Much comparative research still needs to be done before any stipulative claims can be made about how an individual's cognitive abilities can be used to influence decisions about how she or he should be treated. The author stresses the importance of (1) subjectivity and common sense along with the use of empirical data in making decisions about animal welfare, and (2) viewing subjective assessments in the same critical light that is used to evaluate supposedly objective scientific facts. (PsycINFO Database Record (c) 2012 APA, all rights reserved)
Article
The tendency to choose a larger, more delayed reinforcer over a smaller, less delayed one has frequently been termed “selfcontrol.” Three very different research traditions – two models emphasizing the control of local contingencies of reinforcement (Mischel's social learning theory and Herrnstein's matching law) and molar maximization models (specifically optimal foraging theory) – have all investigated behavior within the self-control paradigm. A framework is proposed to integrate research from all three research areas. This framework consists of three parts: a procedural analysis, a causal analysis, and a theoretical analysis. The procedural analysis provides a common procedural terminology for all three areas. The causal analysis establishes that, in all three research traditions, self-control varies directly with the current physical values of the reinforcers; that is, choices increase with reinforcer amount and decrease with reinforcer delay. But self-control also varies according to past events to which a subject has been exposed, and according to current factors other than the reinforcers. Each of the three models has therefore incorporated these indirect effects on self-control by postulating unobservable mechanisms. In all three cases, these mechanisms represent a subject's behavior as a function of a perceived environment. The theoretical analysis demonstrates that evolutionary theory can encompass the research from all three areas by considering differences in the adaptiveness of self-control in different situations. This integration provides a better and more predictive description of self-control.
Article
Five experiments examined adult human females' sensitivity to variation in amount and delay of reinforcement, as well as their impulsiveness (preference for smaller, less delayed reinforcers over larger, more delayed reinforcers), self-control (the opposite of impulsiveness), and indifference (equal preference for larger, more delayed reinforcers and for smaller, less delayed reinforcers). Each experiment used four to five subjects, concurrent variable-interval schedules, reinforcers that consisted of opportunities to earn points exchangeable for money, and varied relative reinforcer amount and delay separately and/or together. Four experiments used a deduction procedure: a random number of points was repeatedly removed from the display counter at regular intervals, independently of the subjects' behavior. Three experiments used independent concurrent schedules; the other two used nonindependent concurrent schedules. One experiment allowed the subjects to play a radio during laboratory sessions. In all experiments the subjects' behavior was better predicted by a molar maximization model than by the generalized matching law. However, the indifference that occurred when the ratio was used did not closely approximate molar maximization. The deduction procedure appeared to have no effect on the subjects' choices. Use of the nonindependent concurrent schedules seemed to result in the subjects showing indifference and low sensitivity to changes in relative reinforcer amount and delay. Use of the radio also seemed to result in indifference. Unlike the behavior of pigeons, the behavior of adult human subjects within a self-control paradigm appears to be well described by molar maximization, but it may be possible to disrupt such behavior by environmental stimuli.
Article
Six brown lemurs and four black lemurs were presented with two stimulus arrays of one and four raisins. Under a reverse-reward contingency, they received the array they did not choose. All subjects showed a strong preference for the larger array and developed a strong side preference bias. When a large-or-none reward contingency was applied (i.e. no reward followed the choice of the larger array, but this array was given for the choice of the smaller array), six of the 10 subjects overcame their side bias and learned to select the smaller array. When a correction procedure was added, all the remaining subjects mastered the task. Performance was maintained when the original reverse-reward contingency was rerun, and when novel array pairs were presented. Several months after the study, six subjects retained a significant preference for choosing the smaller of the two arrays. The results demonstrate a form of self-control in two prosimian species.
Article
Two experiments examined the effect of food deprivation on choice in a discrete-trials self-control paradigm, choice between a larger, more-delayed reinforcer and a smaller, less-delayed reinforcer. In Experiment 1, four pigeons were each deprived to 65%, 80%, and 90% of their free-feeding weights, and the delay to the smaller reinforcer was varied. Deprivation level did not affect choice, but the rate of ineffective key pecks made during the reinforcer delays increased as deprivation increased. In Experiment 2, four pigeons were exposed to conditions in which they were fed up to their 80% free-feeding weights following experimental sessions, and in which they were given no postsession feedings. Both the pigeons' weights and their latencies to insert their heads into the food hopper when food was available were lower when the pigeons were not fed following experimental sessions. Choice showed no change. Deprivation level affects response rate and eating behavior in these procedures, but not choice.
Article
Pigeons were exposed to a self-control paradigm in which they chose between larger, more delayed and smaller, less delayed reinforcers. Reinforcer quality (i.e., the type of grain associated with each alternative) was varied across conditions. Choice behavior was influenced by grain quality; proportions of responses for the larger, more delayed alternative changed as a function of the grains associated with the response alternatives. Furthermore, the percentage deviation from mean baseline response proportions generally decreased as a function of the relative grain types associated with each response alternative. Manipulation of reinforcer quality can significantly influence the degree of self-control typically exhibited by pigeons.
Article
Twenty rats, divided into two groups, served as subjects in an experiment that examined choices between reinforcers that varied in amount or delay. One group received food reinforcers, and the other water reinforcers. No difference was found between the two groups in their values of sA (tendency of choice behavior to vary in accordance with variation in reinforcer amount). However, Group Food had significantly lower values of sD (tendency of choice behavior to vary in accordance with variation in reinforcer delay) than did Group Water, and Group Food's values of (a measure related to self-control-choices of larger, more delayed over smaller, less delayed reinforcers) tended to be greater than for Group Water. Finally, over the session, sA and showed no significant change, overall response rates decreased, and sD increased. Taken together, these results suggest that, independent of deprivation level, self-control for water is less than self-control for food.
Article
A biology-based model of choice is used to examine time-inconsistent preferences and the problem of self-control. Emotion is shown to be the biological substrate of choice, in that emotional systems assign value to ‘goods’ in the environment and also facilitate the learning of expectations regarding alternative options for acquiring those goods. A third major function of the emotional choice systems is motivation. Self-control is shown to be the result of a problem with the inhibition of the motive force of emotion, where this inhibition is necessary for higher level deliberation.
Article
When individual vertebrates loose grip on their life conditions stress symptoms appear and their welfare becomes problematic. Present day research supports the view that stress can originate when an organism experiences a substantial reduction of predictability and/or controllability (P/C) of relevant events. Behavioural (conflict and disturbed behaviour) and physiological (neuro-endocrine and autonomic processes) aspects of a reduction of P/C are reviewed. The highly dynamic patterns of the homeostatic mechanisms activated during stress make it difficult to deduce any simple relationship between stress and welfare. Nevertheless the following conclusions are drawn and defended:- moderate stress may be necessary to optimize vigilance- both the occurrence of one dramatic life event and a long lasting low P/C of relevant life conditions may lead to chronic stress symptoms with a pathological character- the coherence of pre- and post-pathological symptoms is decisive for an evaluation of individual welfare.A list of relevant stress symptoms has been presented, all of which indicate some stage of serious welfare problems. Their occurrence should never be typical of animals living in a farm, laboratory or zoo housing system. However, if after all this is the case, such systems have to be corrected and replaced by more appropriate ones as soon as possible.