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The “olfactory mirror” and other recent attempts to demonstrate self-recognition in non-primate species

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Abstract

The recent attempt by Horowitz (2017) to develop an "olfactory mirror" test of self-recognition in domestic dogs raises some important questions about the kind of data that are required to provide definitive evidence for self-recognition in dogs and other species. We conclude that the "olfactory mirror" constitutes a compelling analog to the mark test for mirror self-recognition in primates, but despite claims to the contrary neither dogs, elephants, dolphins, magpies, horses, manta rays, squid, or ants have shown compelling, reproducible evidence for self-recognition in any modality.

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... Besides apes, rhesus monkeys (Macaca mulatta) also passed the mark test and exhibited mirror-induced self-directed response, akin to the self-recognition, following training with visual somatosensory association (Chang et al. 2015). Among non-primates, the ability of self-recognition has also been reported in Asian elephants (Elephas maximus; Plotnik et al. 2006) and dolphins (Tursiops truncatus; Reiss and Marino 2001), although the evidence derived from a single individual has not been replicated as yet (Gallup and Anderson 2018). Intriguingly, the ability of self-recognition has now been shown also in non-mammals. ...
... Thus, the mirror-mark test has been held as the benchmark behavioural assay for assessing the capacity for self-recognition in animals (Gallup 1970;Keenan et al. 2003). However, the certainty with which animals respond to the mirror-mark test was considered as an evidence of self-awareness has been widely debated and is also questioned (Anderson and Gallup 2015;Gallup and Anderson 2018). ...
... In very first exposure to the mirror, there was spontaneous directed behavioural response in the majority (4/6) of crows to coloured mark (M-M), but not to the other three associations (NM-M, M-S or NM-S). Thus, Indian house crows responded to M-M test differently from magpies (Prior et al. 2008) and jackdaws (Soler et al. 2014) which also showed markdirected behaviours in control conditions, perhaps aided by tactile cues associated with mark application (Gallup and Anderson 2018). Although two of six birds that we tested did not respond to mark test, we would strongly argue that crows possessed the ability of self recognition. ...
Article
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The ability to recognize oneself is separate from recognizing a conspecific. Self-recognition is a higher cognitive function and generally tested by a mirror-mark paradigm, in which the individual recognizes and responds to an inconspicuously placed mark on body from its mirror-reflected image. Although initially suggested to be associated with large-brained mammals, the ability of self-recognition has now been shown in non-mammals, including fish and birds. Hence, studies on many more species might be useful to understand general principles and underlying mechanisms of the evolution of social intelligence. Here, we examined self-recognition ability in Indian house crows (Corvus splendens), by testing them first for mirror-induced responses and then for the mark-directed responses. A circular coloured mark was inconspicuously placed on the throat under the bill where crows could see it only from its mirror-reflected image; a similar black mark placed at identical location which was difficult to be seen served as the control condition. We evaluated how closely crows viewed and inspected the object, and expressed social, contingent and self-directed responses to the mirror and cardboard. Crows exhibited greater preference in response to the mark when in front of the mirror, compared to they were in front of the non-reflective black cardboard. The majority (4/6) crows responded to the mirror-reflected self-image, as evidenced by attempts to remove the coloured mark by using beak or claws; no such response was found in control condition. These results suggest self-recognition by Indian house crows, and support the growing evidence that the ability of self-recognition is more widely present among animals.
... Since Gallup (1970) designed the mark test, the mirror selfrecognition paradigm has been widely used to assess selfrecognition in a wide range of species. Individuals may respond by ignoring the mirror image or considering it as a conspecific (de Waal, Dindo, Freeman, & Hall, 2005;Kusayama, Bischof, & Watanabe, 2000;Medina, Taylor, Hunt, & Gray, 2011;Roma et al., 2007;Shaffer & Renner, 2000;Watanabe, 2002) or much more rarely, showing self-directed behavior in front of the mirror, a response that has only been found in just a few species having very large brains (Gallup, 1970;Gallup & Anderson, 2018;Plotnik, de Waal, & Reiss, 2006;Prior, Schwarz, & Güntürkün, 2008;Reiss & Marino, 2001). Until the beginning of the 21st century, only large-brained mammals had passed the mark test, and thus, considering the vast differences between mammals and birds in the organization of their forebrains (Güntürkün, 2012), it was thought that a mammalian neocortex was necessary for self-recognition. ...
... Two of these issues may be important in magpie studies: the use of stickers as an appropriate replacement for the paint marks used in mammalian mirror studies, and the virtual impossibility of producing a true sham mark control because of the iridescence of magpie feathers. And third, as pointed out by Gallup and Anderson (2018), the two magpies presenting mark-directed behavior in the Prior et al. (2008) study persisted repeatedly in the responses toward their reflection for extended periods of time. This lack of habituation to the mirror is consistent with findings in species not able to pass the mark test, such as monkeys and parrots (Gallup & Suarez, 1991;Pepperberg et al., 1995). ...
... This lack of habituation to the mirror is consistent with findings in species not able to pass the mark test, such as monkeys and parrots (Gallup & Suarez, 1991;Pepperberg et al., 1995). If magpies have the ability of self-recognition it would be expected for them to habituate to the mark, as occurs in chimpanzees (Pan troglodytes): When they realize that it is their behavior that they are observing in the mirror, their interest rapidly diminishes, whereas their self-contingent and mirror-directed exploratory behavior increases (Gallup & Anderson, 2018). ...
Article
Self-recognition in animals is demonstrated when individuals pass the mark test. Formerly, it was thought that self-recognition was restricted to humans, great apes, and certain mammals with large brains and highly evolved social cognition. However, 1 study showed that 2 out of 5 magpies (Pica pica) passed the mark test, suggesting that magpies have a similar level of cognitive abilities to great apes. The scientific advancement depends on confidence in published science, and this confidence can be reached only after rigorous replication of published studies. Here, we present a close replication of the magpie study but using a larger sample size while following a very similar experimental protocol. Like the previous study, in our experiment, magpies showed both social and self-directed behavior more frequently in front of the mirror versus a control cardboard stimulus. However, during the mark test, self-directed behavior proved more frequent in front of the cardboard than in the mirror. Thus, our replication failed to confirm the previous results. Close replications, while not disproving an earlier study, identify results that should be considered with caution. Therefore, more replication studies and additional experimental work is needed to unambiguously demonstrate that magpies are consistently able to pass the mark test. The existence of compelling evidence of self-recognition in other corvid species is discussed in depth. (PsycInfo Database Record (c) 2020 APA, all rights reserved).
... Dogs seemed capable of distinguishing between the olfactory "image" of themselves when modified. Nevertheless, Gallup and Anderson (2018) proposed at least two improvements to provide definitive evidence for selfrecognition in dogs, and also to make the sniff test comparable to the mirror test. The first improvement calls for the need to check the sniffing and post-sniffing behavior towards modified familiar odors because there is a possibility that dogs would show the same response to comparable changes in other familiar odors, such as that of another companion dog ("familiarity hypothesis"). ...
... Here we applied the STSR test to a dog-related species, the grey wolf (Canis lupus). In this test, we incorporated the controls suggested by Gallup and Anderson (2018) and included in the preliminary test performed in Cazzolla Gatti (2016). We applied five trials of the sniff-test for self-recognition to a group of four captive grey wolves, living in malefemale couples in two different enclosures at the Wolf Park in Indiana, USA. ...
... The first trials were a combination of self (S) and self-modified (SM, i.e. each wolf's own urine marked with anise essential oil) scents with a third canister containing: (i) the mark by itself (M), to check the pure interest in the mark; (ii) the urine of the know (partner) wolf modified with the mark (KM), to check the interest in a modified companion's odor; and (iii) the urine of a dog (D), to check the interest in a completely unknown and heterospecific odor. Then, to definitively disentangle the "familiarity hypothesis and the unfamiliarity preference" suggested by Gallup and Anderson (2018), we performed a fourth and a fifth trial with a combination of self (S), known (K; urine from the partner wolf), unknown (U; urine from a nonpartner wolf), and the marked modifications of known and unknown (KM and UM, respectively). These two additional trials were added as further controls to check the ability of wolves to (1) differentiate the "self" odor from "known" (familiar) and "unknown" (unfamiliar) odors, and (2) discern between marked "known" (familiar modified) and "unknown" (unfamiliar modified) odors. ...
Article
Although there are recent claims of a lack of evidence of self-consciousness in many tested species, the ability to recognize oneself in a mirror, which seems an exceedingly rare capacity in the animal kingdom, may not be the only way to check for animal self-awareness (i.e. the capacity to become the object of your own attention). A new testing approach, based on a different sensory modality (such as the sniff-test for self-recognition, STSR), recently proved to be effective with dogs. We applied this sniff test to a group of four captive grey wolves, living in male-female couples in two different enclosures at the Wolf Park in Indiana, USA. In this preliminary study, wolves showed some signs of the ability to recognize themselves through the “olfactory mirror” and exhibited some clues of mark-directed responses, particularly scent-rolling, which may shed more light on this still unclear behavior and represent a sort of olfactory equivalent to passing the original mirror test.
... Since Gallup, Jr.'s, (1970) original mirror self-recognition (MSR) tests in chimpanzees, many other animals have been tested with ambiguous or failing results (e.g., squid [Sepioteuthis lessoniana], Ikeda & Matsumoto, 2007; manta rays [likely Manta birostris], Ari & D'Agostino, 2016;pigeon [Columba liva domestica], Epstein et al., 1981;magpie [Pica pica], Prior et al., 2008; Rhesus monkeys [Macaca mulatta], Rajala et al., 2010;ants [Myrmica sabuleti, M. rubra, M. ruginodis], Cammaerts Tricot & Cammaerts, 2015; horses [Equus caballus], Baragli et al., 2017; cotton-top tamarins [Saguinus oedipus], Hauser et al., 1995;Hauser et al., 2001). According to some researchers, extremely convincing evidence of self-recognition is rare (Anderson & Gallup, 2011;Chang et al., 2017;Gallup et al., 2002;Gallup & Anderson, 2017). With respect to mammals, apart from chimpanzees, MSR appears to have only been demonstrated in other highly social animals including just two common bottlenose dolphins (Tursiops truncatus; Reiss & Marino, 2001), one Asian elephant (Elephas maximus; Plotnik et al., 2006), and only in trained (they did not spontaneously show MSR) Rhesus monkeys (Macaca mulatta; Chang et al., 2017). ...
... Some scientists have suggested that because the MSR test relies on vision, rather than scent, it is therefore an inappropriate test for dogs or wolves (Bekoff, 2014;Cazzolla Gatti, 2016;Horowitz, 2017; but also see Gallup & Anderson, 2017). However, we suggest that the well-developed sense of smell in wolves does not preclude them from passing the visual-based MSR test. ...
... Recent domestic dog self-cognizance research has focused on scent-based tests conducted with the subject's own urine representing "self" (Bekoff, 2001(Bekoff, , 2014Cazolla Gatti, 2016;Horowitz, 2017). However, some assert that additional olfactory tests are needed that include a control for comparable changes in other familiar odors beyond just the dog's own urine (Gallup & Anderson, 2017). It has also been argued that because the dogs in the Horowitz (2017) study did not attempt to smell themselves after smelling the self-altered odor, they did not demonstrate self-recognition per the criteria of the MSR test (Gallup & Anderson, 2017. ...
Article
Mirror self-recognition (MSR) tests have been conducted in a variety of species to assess whether these animals exhibit self-awareness. To date, the majority of animals that have convincingly passed are highly social mammals whose wild counterparts live in complex societies, though there is much debate concerning what constitutes “passing” and what passing means in terms of self-awareness. Amid recent reports that a fish (cleaner wrasse, Labroides dimidiatus) passed, it is intriguing that a mammal as highly social, tolerant, attentive, and cooperative as the gray wolf (Canis lupus) has reportedly failed the test. Given the many possible reasons for failure, we were interested in reexamining wolves as a case study of MSR in socially complex mammals as part of a broader overview of the MSR test. We aimed to elucidate the wolves’ responses at various stages of the MSR test to pinpoint potential problem areas where species-specific modifications to the test may be needed. We evaluated 6 socialized, captive gray wolves during July 2017. At a minimum, wolves did not respond to their reflection as an unfamiliar conspecific. Unfortunately, the wolves rapidly lost interest in the mirror and were uninterested in the applied marks. We note limitations of the MSR test for this species, recommend changes for future MSR tests of wolves, discuss other emerging self-cognizance methods for socially complex canids, and highlight the need for a suite of ecologically relevant, potentially scalable self-cognizance methods. Our findings and recommendations may aid in understanding self-cognizance in other MSR-untested, highly social, cooperatively-hunting, coursing, terrestrial carnivores such as African wild dogs (Lycaon pictus), spotted hyenas (Crocuta crocuta), and African lions (Panthera leo).
... Although there are some interesting results with corvids, only the study with magpies (Prior et al. 2008) reported the occurrence of selfdirected behavior during mirror exposure prior to being marked, but it was not quantified or described. Further studies with these species should be conducted to determine if they will demonstrate spontaneous mirror mediated selfdirected behaviors and to describe such behaviors prior to conducting mark tests with the birds, which has been the standard approach with other species (Gallup and Anderson 2018;Morrison and Reiss 2018). ...
... Suddendorf and Butler proposed that mark test results have been overinterpreted and the current evidence does not support MSR as indicative of self-awareness, as Gallup and others have proposed. Some discussions have centered on determining what type of data replication and methodologies may be required to provide more conclusive evidence for MSR in other species (Gallup and Anderson 2018). Other discussions have focused on the importance of the emergence and demonstration of self-directed behavior prior to being marked, as well as during mark tests, as requisite evidence for MSR (Morrison and Reiss 2018;Reiss and Morrison 2017) and the use of more nuanced ecologically relevant approaches to investigating MSR (Clary and Kelly 2016). ...
... Typically, a researcher is an expert in a defined research topic, such as theory-of-mind development in human infants or behavioral indicators of episodic-like memory in animals. Accordingly, review papers often focus on a specific cognitive ability, such as theory of mind (e.g., Apperly & Butterfill, 2009;Burge, 2018;Penn & Povinelli, 2007;Scott & Baillargeon, 2017), mental time travel (e.g., Cheke & Clayton, 2010;Suddendorf & Corballis, 2007; or self-awareness (e.g., Bard, Todd, Bernier, Love, & Leavens, 2006;Boyle, 2017;Gallup & Anderson, 2018;Schilhab, 2004). In this review, I will take a broader view and address four research topics that are related to human and animal consciousness, namely mirror self-recognition, theory of mind, mental time travel, and the capacity to entertain secondary representations (i.e., section "Cognitive Abilities"). ...
... It is thus questionable, whether and which nonhuman animal species are able to do so. Recently, Gallup and Anderson (2018) reviewed current evidence from studies on mirror self-recognition and concluded that "despite claims to the contrary neither dogs, elephants, dolphins, magpies, horses, manta rays, squid, nor ants have shown compelling, reproducible evidence for self-recognition" (p. 16). ...
Article
Investigations in the cognitive abilities of different animal species and children at different ages have revealed that consciousness comes in degrees. In this review, I will first address four cognitive abilities that are important to discriminate levels of consciousness: mirror self-recognition, theory of mind, mental time travel, and the capacity to entertain secondary representations. I will then examine putative relations between these abilities and assign them to three levels of consciousness (anoetic, noetic, autonoetic). Finally, I will discuss the implications of differences in consciousness for the understanding of behavioral organization in animals and humans and for animal welfare science. I will argue that, on one hand, implicit behavioral rules may account for results obtained in research on theory of mind and mental time travel abilities in animals and children. On the other hand, secondary representations may be the key to explain behaviors based on semantic memory as well as semantic future planning abilities observed in great apes and young children. These considerations are in accordance with the view that an explicit theory of mind and a continuous self through time are unique to humans. Permalink: https://escholarship.org/uc/item/7j68f8n6
... Although many additional species are now being investigated, most of these studies have not provided convincing evidence of mirror self-recognition (Gallup & Anderson, 2018). Thus far, the current consensus suggests that among non-human animals, only great apes show strong evidence of mirror self-recognition (Anderson & Gallup, 2015;Gallup & Anderson, 2018). ...
... Although many additional species are now being investigated, most of these studies have not provided convincing evidence of mirror self-recognition (Gallup & Anderson, 2018). Thus far, the current consensus suggests that among non-human animals, only great apes show strong evidence of mirror self-recognition (Anderson & Gallup, 2015;Gallup & Anderson, 2018). Multiple studies have found that some individuals within each species of great ape pass the "mark test" developed by Gallup (1970). ...
Article
Full-text available
Mirror self‐recognition, as an index of self‐awareness, has been proposed as a precursor for more complex social cognitive abilities, such as prosocial reasoning and cooperative decision‐making. Indeed, evidence for mirror self‐recognition has been shown for animals possessing complex social cognitive abilities such as great apes, dolphins, elephants and corvids. California scrub jays (Aphelocoma californica) have provided strong evidence that non‐human animals are capable of mental state attribution. For instance, scrub jays are reported to use their experience stealing the food of others to infer that other birds may similarly intend to steal from them. If a concept of “self” is required for such complex social cognitive abilities, then scrub jays might be expected to show mirror self‐recognition. Thus, we examined whether California scrub jays are capable of mirror self‐recognition using two experimental contexts: a caching task and the mark test. During the caching task, we compared the extent to which scrub jays protected their food after caching alone, in the presence of a conspecific and in the presence of a mirror. The birds did not engage in more cache protection behaviours with a mirror present than when caching alone, suggesting scrub jays may have recognized their reflection and so did not expect cache theft. Alternative explanations for this behaviour are also discussed. During the mark test, the scrub jays were surreptitiously marked with a red or plumage‐coloured control sticker. The scrub jays showed no evidence of mirror self‐recognition during the mark test, as the birds did not preferentially attempt to remove the red mark in the presence of a mirror. Together, the results provide mixed evidence of the mirror self‐recognition abilities of California scrub jays. We highlight the need to develop alternative approaches for evaluating mirror self‐recognition in non‐human animals to better understand its relationship with complex social cognition.
... To date, in the avian field, only a few species have been formally tested for MSR. Among those, only magpies and Indian crows have been reported to successfully pass this test, although the evidence provided is highly controversial (Anderson & Gallup, 2015;Buniyaadi, Taufique, & Kumar, 2020;Gallup & Anderson, 2018;Prior, Schwarz, & Güntürkün, 2008). Somatosensory feedback enhanced by the application of the mark and intrinsic motivational factors have been identified as the main crucial factors that might underline this patchy pattern of findings across avian species, as well as in other species (Anderson & Gallup, 2015;Buniyaadi et al., 2020;De Veer & Van Den Bos, 1999;Gallup & Anderson, 2018;Heyes, 1994Heyes, , 1995Heyes, , 1996Prior et al., 2008;Soler, Pérez-Contreras, & Peralta-Sánchez, 2014;van Buuren, Auersperg, Gajdon, Tebbich, & von Bayern, 2018;Vanhooland, Bugnyar, & Massen, 2020). ...
... Among those, only magpies and Indian crows have been reported to successfully pass this test, although the evidence provided is highly controversial (Anderson & Gallup, 2015;Buniyaadi, Taufique, & Kumar, 2020;Gallup & Anderson, 2018;Prior, Schwarz, & Güntürkün, 2008). Somatosensory feedback enhanced by the application of the mark and intrinsic motivational factors have been identified as the main crucial factors that might underline this patchy pattern of findings across avian species, as well as in other species (Anderson & Gallup, 2015;Buniyaadi et al., 2020;De Veer & Van Den Bos, 1999;Gallup & Anderson, 2018;Heyes, 1994Heyes, , 1995Heyes, , 1996Prior et al., 2008;Soler, Pérez-Contreras, & Peralta-Sánchez, 2014;van Buuren, Auersperg, Gajdon, Tebbich, & von Bayern, 2018;Vanhooland, Bugnyar, & Massen, 2020). ...
Article
Pioneering research on avian behaviour and cognitive neuroscience have highlighted that avian species, mainly corvids and parrots, have a cognitive tool kit comparable with apes and other large-brained mammals, despite conspicuous differences in their neuroarchitecture. This cognitive tool kit is driven by convergent evolution, and consists of complex processes such as casual reasoning, behavioural flexibility, imagination, and prospection. Here, we review experimental studies in corvids and parrots that tested complex cognitive processes within this tool kit. We then provide experimental examples for the potential involvement of metacognitive skills in the expression of the cognitive tool kit. We further expand the discussion of cognitive and metacognitive abilities in avian species, suggesting that an integrated assessment of these processes, together with revised and multiple tasks of mirror self-recognition, might shed light on one of the most highly debated topics in the literature—self-awareness in animals. Comparing the use of multiple assessments of self-awareness within species and across taxa will provide a more informative, richer picture of the level of consciousness in different organisms.
... Since Gallup's initial findings, the literature has swayed from conservative (only humans, chimpanzees, orangutans have self-face recognition) to today with more liberal interpretations which includes adding animals such as elephants, dolphins and magpies (Gallup & Anderson, 2018). ...
... Full treatment of the role of brain differences in self-awareness is beyond the scope of this article. What is worth noting here is that many organisms appear to get to the level of self-face recognition with very different brain mechanisms (Gallup & Anderson, 2018). Further, self-other distinguishing could be argued to be a basic life requirement (i.e, bacteria) and while self-face processing in humans may be different in what it represents in humans, it may in fact not be. ...
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While the desire to uncover the neural correlates of consciousness has taken numerous directions, self-face recognition has been a constant in attempts to isolate aspects of self-awareness. The neuroimaging revolution of the 1990’s bought about systematic attempts to isolate the underlying neural basis self-face recognition. These studies, including some of the first fMRI (functional Magnetic Resonance Imaging) studies, revealed a right hemisphere bias for self-face recognition in a diverse set of regions including the insula, the Dorsal Frontal Lobe, the Temporal Parietal Junction and Medial Temporal Cortex. Confirmation of these data (which are correlational) was provided by TMS (Transcranial Magnetic Stimulation) and patients in which direct inhibition or ablation of right hemisphere regions leads to a disruption or absence of self-face recognition. These data are consistent with a number of theories including a right hemisphere dominance for self-awareness and/or a right hemisphere specialization for identifying significant social relationships including to oneself.
... Nonetheless, as an olfactory parallel to the mirror mark test, dogs that sample a container of their own odor which has been tainted with a strange odor fail to show signs of attempting to then investigate their own body odor directly. In stark contrast to the way chimpanzees react when they see strange marks on their faces (Gallup & Anderson, 2018). ...
... However, it is important to stress that critical evaluation of a claim for self-recognition in any species is not a matter of taking sides or a simple matter of dialogue and debate. Ultimately such claims are a matter of evidence, and to avoid false claims becoming widely accepted as true the evidence must be based on rigorous and appropriate methods (Gallup & Anderson, 2018). ...
... Since Gallup's initial findings, the literature has swayed from conservative (only humans, chimpanzees, and orangutans have self-face recognition) to today with more liberal interpretations that include the addition of animals such as elephants, dolphins, and magpies [52]. ...
... Other attempts to modify the test have included making the test more phenotypically relevant by using olfaction rather than vision [69]. While this is but a brief summary, we remain skeptical about SFR in non-great apes (with the exception of dolphins) and conclude that more evidence is needed before we consider organisms outside of apes and dolphins to have SFR abilities [52]. ...
Article
Full-text available
While the desire to uncover the neural correlates of consciousness has taken numerous directions, self-face recognition has been a constant in attempts to isolate aspects of self-awareness. The neuroimaging revolution of the 1990s brought about systematic attempts to isolate the underlying neural basis of self-face recognition. These studies, including some of the first fMRI (functional magnetic resonance imaging) examinations, revealed a right-hemisphere bias for self-face recognition in a diverse set of regions including the insula, the dorsal frontal lobe, the temporal parietal junction, and the medial temporal cortex. In this systematic review, we provide confirmation of these data (which are correlational) which were provided by TMS (transcranial magnetic stimulation) and patients in which direct inhibition or ablation of right-hemisphere regions leads to a disruption or absence of self-face recognition. These data are consistent with a number of theories including a right-hemisphere dominance for self-awareness and/or a right-hemisphere specialization for identifying significant social relationships, including to oneself.
... These results remain controversial. Gordon Gallup, the creator of the first mirror test in other animals (Gallup 1970) has been a key skeptic of many of the above results (Gallup & Anderson 2018). A full review of MSR (mirror self-recognition) in these many cases is beyond the scope of this paper. ...
... These results remain controversial. Gordon Gallup, the creator of the first mirror test in other animals (Gallup 1970) has been a key skeptic of many of the above results (Gallup & Anderson 2018). A full review of MSR (mirror self-recognition) in these many cases is beyond the scope of this paper. ...
Article
Several influential philosophers and scientists have advanced a framework, often called Neo-Cartesianism (NC), according to which animal suffering is merely apparent. Drawing upon contemporary neuroscience and philosophy of mind, Neo-Cartesians challenge the mainstream position we shall call Evolutionary Continuity (EC), the view that humans are on a nonhierarchical continuum with other species and are thus not likely to be unique in consciously experiencing negative pain affect. We argue that some Neo-Cartesians have misconstrued the underlying science or tendentiously appropriated controversial views in the philosophy of mind. We discuss recent evidence that undermines the simple neuroa-natomical structure-function correlation thesis that under-girds many Neo-Cartesian arguments, has an important bearing on the recent controversy over pain in fish, and places the underlying epistemology framing the debate between NC and EC in a new light that strengthens the EC position.
... Mammal species that have reported to pass the mirror test include the chimpanzee (Pan troglodytes), the orangutan (Pongo pygmaeus), the bonobo (Pan paniscus), the gorilla (Gorilla gorilla gorilla), the bottlenose dolphin (Tursiops truncatus), the killer whale (Orcinus orca) and the Asian elephant (Elephas maximus) (Gallup, 1970;Lethmate and Dücker, 1973;Marten and Psarakos, 1994;Westergaard and Hyatt, 1994;Delfour and Marten, 2001;Reiss and Marino, 2001;Sarko et al., 2002;Plotnik et al., 2006;Posada and Colell, 2007;Morrison and Reiss, 2018). However, these species except great apes have been questioned with insufficient evidence for showing MSR (Gallup, 2018). Also, the cleaner wrasse (Labroides dimidiatus) is reported to pass the mirror test (Kohda et al., 2019), but this assertion is highly contested (Gallup and Anderson, 2020). ...
Article
Scientists have spent great efforts exploring self-recognition in non-human animals using the mirror test. In avian species, some of the passerines have passed the test, although the findings are still under debate. The present study aimed at investigating mirror self-recognition ability and making a comparative study of mirror responses in two avian species, the common hill myna from the Passeriformes and the African grey parrot from the Psittaciformes. The subjects underwent four stages of experiment: habituation, baseline, mirror exposure and mark test. Our subjects spent significantly longer time in gazing into the mirror than the plexiglass as control. We also found they significantly increased the durations of grooming behaviour when presented with the mirror. No species difference was detected in the above two behaviours. However, the African grey parrots were more likely to approach the mirror than the common hill mynas, indicating their different ways of mirror exploration. All subjects failed to pass the mark test. In this study, we found no evidence of mirror self-recognition in the common hill myna and the African grey parrot.
... Within the primates, great apes such as chimpanzees, Pan troglodytes (Gallup 1970;Suarez and Gallup 1981;Povinelli et al. 1993) and orangutans, Pongo pygmaeus (Suarez and Gallup 1981) have passed the mirror self-recognition test, and these findings have been independently replicated (Gallup et al. 2011;Anderson and Gallup 2015). Outside of the primates, evidence of self-recognition in mammals such as Asian elephants, Elephas maximus (Plotnik et al. 2006) and bottlenose dolphins, Tursiops truncatus (Reiss and Marino 2001) and birds such as the Eurasian magpie, Pica pica (Prior et al. 2008) have been reported, however, concerns have been raised about these studies due to their small sample sizes, lack of replication or failed replication (Gallup and Anderson 2018;Soler et al. 2020). In addition to those that have passed the mirror selfrecognition test, some species have been suggested to be at an intermediate level between reacting to their reflection as a stranger and recognising it as self (e.g. ...
Article
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Responses to mirrors vary in non-human animals. Many species respond socially to mirrors with relatively few species demonstrating self-recognition in mirrors. In this study, we investigated the responses of ferrets to mirrors. Six adult ferrets (3 males, 3 females, all over a year old) were exposed to mirrors and their responses were investigated over three experimental conditions (baseline, mirror preference, mark test) in a repeated measures design. Upon initial presentation, the ferrets showed more approach and sniffing behaviour toward the mirror than the non-reflective surface. The ferrets also showed a preference for the mirror and spent more time in close proximity to the mirror than the non-reflective surface. In the mirror mark test, the ferrets showed more approach, sniffing and self-exploration behaviour when they were marked and presented with the mirror compared to when they were marked and presented with the non-reflective surface, or when they were sham-marked and presented with either surface. Our findings are suggestive that ferrets show interest in mirrors and that further study exploring the responses of ferrets to mirrors is warranted.
... As stated elegantly by Wittek et al. (2021), we need to move beyond the pass/fail criteria of the mark test as a measure of self-recognition and adopt a more gradualist approach. The insistence that the mark test is the sole evidence for self-recognition also has led to the refusal to legitimise studies that have demonstrated animals passing the mark test; when they fail the mark test they are said to lack the cognitive capability of self-recognition, but when they pass, it is attributed to arbitrary details in the methods that supposedly gave false positives for mirror self-recognition (Anderson & Gallup, 2015, Gallup & Anderson, 2018, Gallup & Anderson, 2020. ...
Article
The extent to which different species display self-recognition is a controversial topic in comparative cognition. Self-recognition is widely validated through the mark test in which a dye or paint mark is applied surreptitiously to the subject. Mark-directed responses in the presence of a mirror are taken as evidence of self-recognition. Over the past 50 years many different species have been administered the mark test, but only a handful have passed it. Some have suggested that species that pass the mark test are those that have a complex social structure. In this review, we propose, rather, that the reason why an animal fails the mark test is because the study has failed to adequately account for one or more of three crucial elements: mirror understanding, self-exploration, and mark saliency. Alternative methods of validating mirror self-recognition also are discussed.
... It is beyond the scope of this article to provide a review of this literature. However, it should be noted that various concerns about the methodologies and behavioral criteria used to assess mirror self-recognition in these studies have been raised, calling into question the strength of the evidence of mirror self-recognition in these non-primate species (see Gallup and Anderson 2018;Soler et al. 2014). Nevertheless, the results of these studies do at least suggest the possibility that the capacity for mirror self-recognition has evolved in a number of distinct non-primate species. ...
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Chimpanzees and humans are capable of recognizing their own reflection in mirrors. Little is understood about the selective pressures that led to this evolved trait and about the mechanisms that underlie it. Here, we investigated the hypothesis that mirror self-recognition in chimpanzees is the byproduct of a developed form of self-awareness that was naturally selected for its adaptive use in social cognitive behaviors. We present here the first direct attempt to assess the social cognition hypothesis by analyzing the association between mirror self-recognition in chimpanzees, as measured by a mirror-mark test, and their performance on a variety of social cognition tests. Consistent with the social cognition hypothesis, chimpanzees who showed evidence of mirror self-recognition in the mark test tended to perform significantly better on the social cognition tasks than those who failed the mark test. Additionally, the data as a whole fit the social cognition hypothesis better than the main competing hypothesis of mirror self-recognition in great apes, the secondary representation hypothesis. Our findings strongly suggest that the evolutionary origins of great apes’ and humans’ capacity to understand ourselves, as revealed by our capacity to recognize ourselves in mirrors, are intimately linked to our ability to understand others.
... Horowitz's study translates the MSR study for dogs (who primarily rely on olfaction) who have shown interest in their own odours, implying the dogs' recognition of the odour that came from them. Gallup and Anderson (2018) have reported their critique of the olfactory mirror with dogs. A task exploiting an ecologically relevant behaviour has been used to assess the self-recognition of Clark's nutcrackers (Nucifraga columbiana) (Clary and Kelly, 2016) and California scrub jays (Aphelocoma californica) (Clary et al., 2019). ...
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Mirror self-recognition (MSR) is considered a crucial step in the emergence of self-cognition. The MSR paradigm has become a standard method for evaluating self-cognition in several species. For example, Eurasian magpies and Indian house crows have passed the mark test for self-cognition, whereas efforts to find MSR in other corvid species have failed. However, no literature has conducted MSR tests on azure-winged magpies, a species of corvids. Therefore, the current research aimed to investigate the MSR behaviours of azure-winged magpies upon looking into a mirror for the first time. The study included four tests: (1) mirror preference and standardised mirror exploration, (2) single vertical mirror test, (3) mark test and (4) mirror-triggered search test. The azure-winged magpies displayed immense curiosity towards the mirror and their images in the mirror in Test 1&2. In the subsequent mark tests, they failed to recognise themselves in the mirror and regarded their images as conspecifics. Behaviour analysis showed no significant difference between marked and unmarked behaviours. Finally they seemed to infer the presence of bait from the image in the mirror, but were found to fail to understand that the location of the bait in the mirror was the same as that in the real world. For a better insight into the MSR behaviour of azure-winged magpies, research studies involving prolonged mirror exposure and training are recommended.
... In connection with the growing criticism of this methodological approach, more and more authors are striving to offer alternative methods for identifying the ability of self-recognition. In particular, the phenomenon of recognizing own chemical traces on surrounding objects, the so-called "olfactory mirror", is investigated [16][17][18]. ...
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Body awareness was studied experimentally in the rat snakes Elaphe radiata. The experimental design required that the snakes take into account the limits of their bodies when choosing a suitable hole for penetration into the shelter. The experimental setup consisted of two compartments, a launch chamber and a shelter, separated by a partition with openings of different diameters. The diameters of the holes and/or their position in the partition were changeable. The subjects were 20 snakes divided into two groups, for one of which only the locations of the holes varied; for another, both the location of the holes and the limits of the body varied. The body was increased by feeding the snakes. In the course of the first three experimental series the snakes formed the skill of taking into account the body limits, which manifested in the reduced number of unsuccessful attempts to select holes too small for their bodies. During the fourth series, with the locations of holes randomized for each trial, the snakes demonstrated behavioral flexibility, significantly more often penetrating into the shelter from the first attempt irrespectively of the location of the suitable hole. We argue that these results demonstrate the body-awareness in snakes.
... Thus, applying adapted versions of the MSR, two studies in dogs (Gatti, 2016;Horowitz, 2017) used olfaction as a mechanism for self-recognition, with dogs being able to recognize their own smell. Nonetheless, Gallup and Anderson (2018) argued that the "olfactory mirror" recognition test lacked important control conditions, undermining the results. Specifically, in his critique to the Horowitz study, he noted that dogs spent more time investigating another dog's odor than their own because they habituate to their own odor. ...
Article
The capacity to be self-aware is regarded as a fundamental difference between humans and other species. However, growing evidence challenges this notion, indicating that many animals show complex signs and behaviors that are consonant with self-awareness. In this review, we suggest that many animals are indeed selfaware, but that the complexity of this process differs among species. We discuss this topic by addressing several different questions regarding self-awareness: what is selfawareness, how has self-awareness been studied experimentally, which species may be self-aware, what are its potential adaptive advantages. We conclude by proposing alternative models for the emergence of self-awareness in relation to species evolutionary paths, indicating future research questions to advance this field further.
... The behaviour in one animal is automatically triggered by the similar behaviour of others (Zentall, 2001) in primates), and evidence in non-primate species (e.g. elephants) is often based on single individual findings (see Gallup and Anderson, 2018, for a review on MSR in non-primates). Moreover, it remains unresolved whether MSR in animals demonstrates S-O distinction or whether MSR can be explained alternatively, and whether S-O distinction automatically implies self-awareness, as disputed in a recent paper on MSR in cleaner fish (Labroides dimidiatus) (Kohda et al., 2019; but see de Waal, 2019, for a critical discussion of Kohda et al., 2019, and the application of a gradual perspective on MSR, rather than the current binary one). ...
Article
The aim of this review is to discuss recent arguments and findings in the comparative study of empathy. Based on a multidisciplinary approach including psychology and ethology, we review the non-human animal literature concerning theoretical frameworks, methodology, and research outcomes. One specific objective is to highlight discrepancies between theory and empirical findings, and to discuss ambiguities present in current data and their interpretation. In particular, we focus on emotional contagion and its experimental investigation, and on consolation and targeted helping as measures for sympathy. Additionally, we address the feasibility of comparing across species with behavioural data alone. One main conclusion of our review is that animal research on empathy still faces the challenge of closing the gap between theoretical concepts and empirical evidence. To advance our knowledge, we propose to focus more on the emotional basis of empathy, rather than on possibly ambiguous behavioural indicators, and we provide suggestions to overcome the limitations of previous research.
... The other weakness of the test is that it does not imply any interaction with the dogs' own body. If dogs could identify the odors they should have smelled themselves after smelling the modified samples analogously to the subjects who touch the mark on their body in the mirror test (Gallup and Anderson 2018). Although studies about self-recognition by using different modalities can be important, from the evolutionary point of view self-representation could more likely manifest itself during locomotion (Povinelli and Cant 1995;Moore et al. 2007). ...
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With very few exceptions, no coherent model of representing the self exists for nonhuman species. According to our hypothesis, understanding of the Self as an object’ can also be found in a wide range of animals including the dog, a fast-moving terrestrial predator/scavenger, with highly developed senses and complex cognitive capacity. We tested companion dogs in three experiments in which they faced three different variations of the same physical challenge: passing through an opening in a wall. We predicted that if dogs are capable of representing their own body size, they will react differently when faced with adequate or too small openings. We found that dogs started to move towards and approached the too small openings with significantly longer latencies than the suitable ones; and upon reaching it, they did not try to get through the too small openings. In another experiment, the medium-size (still large enough) opening was approached with latencies that fell between the latencies measured in the cases of the very large or the too small openings. Having discussed the potential underlying mechanisms, we concluded that our results convincingly assume that dogs can represent their own body size in novel contexts.
... Within birds, magpies (Pica pica) marked on their throats are so far the only species that successfully passed Gallup's MSR test (Prior et al., 2008) although the methods and conclusions were subject to some criticism (Soler et al., 2014;Gallup & Anderson, 2018). Recent work on Clark's nutcrackers (Nutifraga columbiana), another corvid species, although inconclusive, suggests that they may be capable of some form of mirror-guided behaviours as well (Clary & Kelly, 2016). ...
Article
So far only one bird species, a corvid, passed the mark test for mirror self-recognition (MSR) although the results have been questioned. We examined the capacity for MSR in another large-brained avian taxon, parrots, with keas ( Nestor notabilis ) and Goffin’s cockatoos ( Cacatua goffini ). After several weeks of mirror habituation, they were subjected to the mark test using different marks and mark placements while facing horizontal and vertical mirrors simultaneously. The keas had an additional control condition in which their reaction towards a marked or non-marked conspecific behind a transparent partition was compared to their own reflection. No evidence of MSR was found in either species. Keas responded to their reflection comparably to a conspecific behind a clear separation. Goffin’s cockatoos showed fewer social responses towards their horizontal reflection compared to their vertical reflection, suggesting that they may interpret them differently.
... These results indicate that the ability of self-recognition might be more widespread than initially assumed. However, the evidence of successful selfrecognition in many of the aforementioned primate and all of the nonprimate animals are still being disputed (Anderson & Gallup, 2011Gallup & Anderson, 2018). Alternatively, these findings may hint at a more gradualist view on animal self-awareness rather than it being a yes or no concept (de Waal, 2019). ...
Article
Mirror reflections can elicit various behavioral responses ranging from social behavior, which suggests that an animal treats its own reflection as a conspecific, to mirror-guided self-directed behaviors, which appears to be an indication for mirror self-recognition (MSR). MSR is scarcely spread in the animal kingdom. Until recently, only great apes, dolphins, and elephants had successfully passed this test. The range of convergence was, however, expanded by an avian species, the Eurasian magpie (Pica pica). Efforts to find MSR in other corvid species have so far failed, and with only a few studies conducted, the cause of these discrepancies is difficult to identify. In the present study, we examined the responses to mirrors and the ability of MSR in hitherto untested species: the carrion and hooded crows (Corvus corone ssp.). These crows showed a pronounced and lasting interest in the mirror; unlike many species, they did not exhibit social behaviors on their first encounters but immediately started investigating the mirror. Some crows showed contingent behaviors in front of the mirror, but none of the crows showed significant mirror-guided self-directed behaviors nor mark-directed behavior during the subsequent mark test. This lack of mark-directed behavior could not be explained by a lack of interest in the mirror nor in the mark. These findings could indicate that crows lack a concept of self, or the need for other means of investigating self-recognition and self-awareness in avian species. (PsycINFO Database Record (c) 2019 APA, all rights reserved).
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Debates around fishes' ability to feel pain concern sentience : do reactions to tissue damage indicate evaluative consciousness (conscious affect), or mere nociception? Thanks to Braithwaite's discovery of trout nociceptors, and concerns that current practices could compromise welfare in countless fish, this issue's importance is beyond dispute. However, nociceptors are merely necessary, not sufficient, for true pain, and many measures held to indicate sentience have the same problem. The question of whether fish feel pain – or indeed anything at all – therefore stimulates sometimes polarized debate. Here, we try to bridge the divide. After reviewing key consciousness concepts, we identify “red herring” measures that should not be used to infer sentience because also present in non-sentient organisms, notably those lacking nervous systems, like plants and protozoa (P); spines disconnected from brains (S); decerebrate mammals and birds (D); and humans in unaware states (U). These “S.P.U.D. subjects” can show approach/withdrawal; react with apparent emotion; change their reactivity with food deprivation or analgesia; discriminate between stimuli; display Pavlovian learning, including some forms of trace conditioning; and even learn simple instrumental responses. Consequently, none of these responses are good indicators of sentience. Potentially more valid are aspects of working memory, operant conditioning, the self-report of state, and forms of higher order cognition. We suggest new experiments on humans to test these hypotheses, as well as modifications to tests for “mental time travel” and self-awareness (e.g., mirror self-recognition) that could allow these to now probe sentience (since currently they reflect perceptual rather than evaluative, affective aspects of consciousness). Because “bullet-proof” neurological and behavioral indicators of sentience are thus still lacking, agnosticism about fish sentience remains widespread. To end, we address how to balance such doubts with welfare protection, discussing concerns raised by key skeptics in this debate. Overall, we celebrate the rigorous evidential standards required by those unconvinced that fish are sentient; laud the compassion and ethical rigor shown by those advocating for welfare protections; and seek to show how precautionary principles still support protecting fish from physical harm.
Article
The mirror mark test is generally considered to be an indicator of an animal's ability to recognize itself in the mirror. For this test, an animal is confronted with a mirror and has a mark placed where it can see the mark only with the help of the mirror. When the animal extensively touches or interacts with the mark, compared with control conditions, the mirror mark test is passed. Many nonhuman animal species have been tested, but few have succeeded. After magpies and Indian house crows passed, there has been a sustained interest to find out whether other corvids would pass the mirror mark test. Here, we presented 12 carrion crows (Corvus corone corone) with the mirror mark test. There was no significant increase of mark-directed behavior in the mirror mark test, compared with control conditions. We find very few occasions of mark-directed behaviors and have to interpret them in the context of self-directed behavior more generally. In addition, we show that our crows were motivated to interact with a mark when it was visible to them without the aid of a mirror. We conclude that our crows fail the test, and thereby replicate previous studies showing a similar failure in corvids, and crows in particular. Because our study adds to the growing literature of corvids failing the mirror mark test, the issue of mirror self-recognition in these birds remains controversial. (PsycInfo Database Record (c) 2020 APA, all rights reserved).
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Most mirror-image stimulation studies (MIS) have been conducted on social and diurnal animals in order to explore self-recognition, social responses, and personality traits. Small, nocturnal mammals are difficult to study in the wild and are under-represented in experimental behavioral studies. In this pilot study, we explored the behavioral reaction of a small nocturnal solitary forager-the grey mouse lemur (Microcebus murinus)-an emergent animal model in captivity. We assessed whether MIS can be used to detect a repeatable behavioral reaction, whether individuals will present a similar reaction toward a conspecific and the mirror, and whether males and females respond similarly. We tested 12 individuals (six males and six females) twice in three different contexts: with a mirror, with a live conspecific, and with a white board as a neutral control. We detected significant repeatability for the activity component of the behavioral reaction. There was a significant effect of the context and the interaction between presentation context and sex for avoidance during the first session for males but not for females. Males avoided the mirror more than they avoided a live conspecific. This pilot study opens a discussion on the behavioral differences between males and females regarding social interactions and reproduction in the nocturnal solitary species, and suggests that males are more sensitive to context of stimulation than females.
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The recent article by Baragli, Scopa, Maglieri, and Palagi (Anim Cogn https://doi.org/10.1007/s10071-021-01502-7, 2021) that claims to demonstrate mirror self-recognition (MSR) in horses is not based on compelling evidence. We identify problems with their experimental procedures, data, and assertion about “demonstrating MSR at group level.” Examples of these problems include incomplete experimental design, absence of important control conditions, inappropriate terminology, suboptimal mark application procedures and coding of videos, ambiguity of videos presented as supporting evidence, and inconsistencies in data presentation and interpretation. It is not the case that their study “marks a turning point in the analytical technique of MSR exploration.”
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Rodents are known to signal using odors to communicate information including their sex, age, reproductive state, and unique identity. Conspecifics can recognize these signals and behaviorally respond in sex‐specific ways. However, we know little about how males and females might differ in their responses to signals from individuals or how the sexes might differ in their ability to recognize their own identity. Such signals of identity are important because they can modulate the behavior of receivers, and allow for responses related to aggression, territory maintenance, affiliation, and reproduction. To assess how males and females might differ in their responses to individual familiar and novel social signals, and their own individual signals compared to novel same‐sex conspecifics, we tested southern giant pouched rats (Cricetomys ansorgei) using a habituation–discrimination paradigm. Only females showed individual recognition and discriminated among males, preferring novel males. Females also discriminated between their own scent and a novel conspecific odor. Males did not discriminate or demonstrate individual recognition. Male and female differences in response to opposite‐sex odors demonstrated that males do not discriminate between familiar and novel reproductively available females, but females discriminate and prefer to investigate novel males. Female pouched rats discriminated between urine odors from novel and familiar males, but male pouched rats did not discriminate between urine odors from novel and familiar females. Other sex differences in social odor discrimination are discussed to understand sex‐specific behaviors.
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Mirror self-recognition (MSR), widely regarded as an indicator of self-awareness, has not been demonstrated consistently in gorillas. We aimed to examine this issue by setting out a method to evaluate gorilla self-recognition studies that is objective, quantifiable, and easy to replicate. Using Suarez and Gallup’s (J Hum Evol 10:175–183, 1981) study as a reference point, we drew up a list of 15 methodological criteria and assigned scores to all published studies of gorilla MSR for both methodology and outcomes. Key features of studies finding both mark-directed and spontaneous self-directed responses included visually inaccessible marks, controls for tactile and olfactory cues, subjects who were at least 5 years old, and clearly distinguishing between responses in front of versus away from the mirror. Additional important criteria include videotaping the tests, having more than one subject, subjects with adequate social rearing, reporting post-marking observations with mirror absent, and giving mirror exposure in a social versus individual setting. Our prediction that MSR studies would obtain progressively higher scores as procedures and behavioural coding practices improved over time was supported for methods, but not for outcomes. These findings illustrate that methodological rigour does not guarantee stronger evidence of self-recognition in gorillas; methodological differences alone do not explain the inconsistent evidence for MSR in gorillas. By implication, it might be suggested that, in general, gorillas do not show compelling evidence of MSR. We advocate that future MSR studies incorporate the same criteria to optimize the quality of attempts to clarify the self-recognition abilities of gorillas as well as other species.
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The question of whether animals have some sort of self-awareness is a topic of continued debate. A necessary precondition for self-awareness is the ability to visually discriminate the self from others, which has traditionally been investigated through mirror self-recognition experiments. Although great apes generally pass such experiments, interpretations of results have remained controversial. The aim of this study was to investigate how bonobos ( Pan paniscus ) respond to different types of images of themselves and others, both before and after prolonged mirror exposure. We first presented presumably mirror-naive subjects with representations of themselves in three different ways (mirror image, contingent and non-contingent video footage) as well as representations of others (video footage of known and unknown conspecifics). We found that subjects paid significantly less attention to contingent images of themselves (mirror image, video footage) than to non-contingent images of themselves and unfamiliar individuals, suggesting they perceived the non-contingent self-images as novel. We then provided subjects with three months of access to a large mirror centrally positioned in the enclosure. Following this manipulation, subjects showed significantly reduced interest in the non-contingent self-images, while interest in unknown individuals remained unchanged, suggesting that the mirror experience has led to a fuller understanding of their own self. We discuss implications of this preliminary investigation for the on-going debate on self-awareness in animals.
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Since the pioneering work in chimpanzees, mirror self-recognition (MSR), the ability to recognise oneself in a mirror, has been reported in great apes, Asian elephants, dolphins, and some social birds using the mark test, in which animals that possess MSR touch an imperceptible mark on their own bodies only when a mirror is present. However, giant pandas, which are solitary, failed to pass the mark test, suggesting that MSR evolved solely in highly social animals. In contrast to the increasing evidence of MSR in mammals and birds, little is known about MSR in fish. A Tanganyikan cichlid, Neolamprologus pulcher, is a good candidate for study because these fish live in highly social groups and recognise conspecifics about as rapidly as primates. We examined their responses to a mirror image and tested whether N. pulcher could pass the mark test. When the mirror was first exposed, they stayed in front of the mirror and exhibited aggressive behaviour towards the mirror image. These social behaviours suggested that the focal fish perceived the mirror image as an unfamiliar conspecific. The social responses decreased over the following days, as has generally been the case in animals with MSR. After mark injection, we found no increase in scraping behaviour or prolonged observation of the marked side. These results show a lack of contingency checking and mark-directed behaviours, meaning that N. pulcher failed to pass the mark test and did not recognise their self-image in the mirror.
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Introduction Infant body odor is subjectively pleasant to parents and activates reward areas in the brain. Hence, body odor perception might contribute to parental bonding. However, it is unknown whether the perceived pleasantness of children’s body odor varies over the course of a child’s development. Methods Two hundred and thirty-five parents (M = 36.9 years, SD = 7.3) were asked to assess the personal odor pleasantness of their children (N = 367; M = 9.3 years, SD = 6.4). Results Odor pleasantness was found to decrease as a function of children’s age. Neither sex of the parent nor sex of the child contributed significantly to this effect. Conclusions We propose that the effect of age-related changes on personal odor pleasantness reflects olfactory modulation of parental-child relationships. Implications Our study suggests that perception of young children’s personal odor as pleasant may contribute to bonding and thereby caretaking, which is needed to a lesser degree after puberty than before.
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We review research on reactions to mirrors and self-recognition in nonhuman primates, focusing on methodological issues. Starting with the initial demonstration in chimpanzees in 1970 and subsequent attempts to extend this to other species, self-recognition in great apes is discussed with emphasis on spontaneous manifestations of mirror-guided self-exploration as well as spontaneous use of the mirror to investigate foreign marks on otherwise nonvisible body parts-the mark test. Attempts to show self-recognition in other primates are examined with particular reference to the lack of convincing examples of spontaneous mirror-guided self-exploration, and efforts to engineer positive mark test responses by modifying the test or using conditioning techniques. Despite intensive efforts to demonstrate self-recognition in other primates, we conclude that to date there is no compelling evidence that prosimians, monkeys, or lesser apes-gibbons and siamangs-are capable of mirror self-recognition.
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Some animals are capable of recognizing themselves in a mirror, which is considered to be demonstrated by passing the mark test. Mirror self-recognition capacity has been found in just a few mammals having very large brains and only in one bird, the magpie (Pica pica). The results obtained in magpies have enormous biological and cognitive implications because the fact that magpies were able to pass the mark test meant that this species is at the same cognitive level with great apes, that mirror self-recognition has evolved independently in the magpie and great apes (which diverged 300 million years ago), and that the neocortex (which is not present in the bird's brains) is not a prerequisite for mirror self-recognition as previously believed. Here, we have replicated the experimental design used on magpies to determine whether jackdaws (Corvus monedula) are also capable of mirror self-recognition by passing the mark test. We found that our nine jackdaws showed a very high interest towards the mirror and exhibited self-contingent behavior as soon as mirrors were introduced. However, jackdaws were not able to pass the mark test: both sticker-directed actions and sticker removal were performed with a similar frequency in both the cardboard (control) and the mirror conditions. We conclude that our jackdaws' behaviour raises non-trivial questions about the methodology used in the avian mark test. Our study suggests that the use of self-adhesive stickers on sensitive throat feathers may open the way to artefactual results because birds might perceive the stickers tactilely.
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After prolonged exposure to their reflected images in mirrors, chimpanzees marked with red dye showed evidence of being able to recognize their own reflections. Monkeys did not appear to have this capacity.
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Interest in the comparative study of mirror self-recognition persists because of the implications for self-awareness and the possibility of a cognitive divide among primates. Evidence from many studies carried out over 40 years shows that humans and great apes are distinguished from other nonhuman primates by their capacity for self-recognition. We review some recent developments in the field, with critical reference to claims that monkeys show self-recognition. Focusing on methodological issues, we conclude that there is no compelling evidence for mirror self-recognition in any non-ape primate species.
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As a result of a long-term, longitudinal project initiated in 1978, a pair of rhesus macaques (Macaca mulatta) housed together in front of a mirror all their lives now exhibit relatively little interest in their reflection. Previous work has shown, however, that simply moving the mirror to a new location produces a short-term reinstatement of social responding to their images. As an extension of these findings, in this study the mirror was left in the same position but turned away from the cage. On turning the mirror back to face the cage 5 days later, both animals reacted as if confronted with another pair of monkeys and directed a burst of social responses at the mirror.
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This study investigated sex differences in the ability to recognize one's own body odor accompanied by an attempt to account for variance in this ability by comparing ratings of self-body odor and other odors on a visual analog scale (VAS). Whereas over half (59.4%) of the females were able to identify their own odor, only one out of 18 (5.6%) males were able to recognize their own odor. Females rated their own secretions as significantly lower on a pleasant-positive factor than males rated their own odors (axillary secretions), but there was no difference in ratings between those who could and those who could not identify their own odor. The dimensions tapped by the VAS used in this study do not seem to account for the ability to identify one's own body odors.
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Considered an indicator of self-awareness, mirror self-recognition (MSR) has long seemed limited to humans and apes. In both phylogeny and human ontogeny, MSR is thought to correlate with higher forms of empathy and altruistic behavior. Apart from humans and apes, dolphins and elephants are also known for such capacities. After the recent discovery of MSR in dolphins (Tursiops truncatus), elephants thus were the next logical candidate species. We exposed three Asian elephants (Elephas maximus) to a large mirror to investigate their responses. Animals that possess MSR typically progress through four stages of behavior when facing a mirror: (i) social responses, (ii) physical inspection (e.g., looking behind the mirror), (iii) repetitive mirror-testing behavior, and (iv) realization of seeing themselves. Visible marks and invisible sham-marks were applied to the elephants' heads to test whether they would pass the litmus “mark test” for MSR in which an individual spontaneously uses a mirror to touch an otherwise imperceptible mark on its own body. Here, we report a successful MSR elephant study and report striking parallels in the progression of responses to mirrors among apes, dolphins, and elephants. These parallels suggest convergent cognitive evolution most likely related to complex sociality and cooperation. • cognition • mirror self-recognition • theory of mind • intelligence • empathy
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While domestic dogs, Canis familiaris, have been found to be skillful at social cognitive tasks and even some meta-cognitive tasks, they have not passed the test of mirror self-recognition (MSR). Acknowledging the motivational and sensory challenges that might hinder performance, even before the question of self-recognition is broached, this study creates and enacts a novel design extrapolated from the species' natural behaviour. Given dogs' use of olfactory signals in communication, this experiment presents dogs with various canisters for approach and investigation. Each holds an odorous stimulus: in the critical test, either an “olfactory mirror” of the subject − the dog's own urine − or one in which the odour stimulus is modified. By looking at subjects' investigation times of each canister, it is shown that dogs distinguish between the olfactory “image” of themselves when modified: investigating their own odour for longer when it had an additional odour accompanying it than when it did not. Such behaviour implies a recognition of the odour as being of or from “themselves." The ecological validity of this odour presentation is examined by presenting to the subjects odours of other known or unknown dogs: dogs spend longer investigating the odour of other dogs than their own odour. Finally, in a second experiment, subjects spent longer with the modified stimulus than with the modified odour by itself, indicating that novelty alone does not explain the dogs' behavior. This study translates the MSR study for a species whose primary sensory modality is olfaction, and finds both that natural sniffing behaviour can be replicated in the lab and that dogs show more investigative interest in their own odours when modified.
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Presents an overview of known facts regarding self-recognition in primates, addressing the issue of how some nonhuman and most human primates come to understand that a reflection, televised image, or photograph can be a representation of themselves. Issues of specific focus include: chimpanzees and the revelation of self-recognition; extensions and inclusions of self-recognition in primates; monkeys and the "monkey in the mirror"; the hypothesis of a qualitative cognitive difference; and challenges to this field of study. (PsycINFO Database Record (c) 2012 APA, all rights reserved)
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[examine] the evidence that a monkey looking at itself in a mirror "thinks" its reflection is a conspecific / [suggest that] in both monkeys and many nonprimate species a variety of phenomena normally induced by a conspecific may occur when the conspecific is replaced by a mirror / [argue] that, in the absence of convincing evidence for self-recognition in monkeys, such phenomena reinforce the view that monkeys, like most other animals, do not progress beyond a "social" stage when perceiving their own reflections exploring species differences / overt social responses to mirrors / visual reinforcement / mirror image as a stand-in for social stimuli (PsycINFO Database Record (c) 2012 APA, all rights reserved)
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Cephalopod mollusks are found virtually everywhere throughout the world's oceans. They are highly mobile invertebrates that have evolved behavioral and morphological defenses against vertebrate predators. Unlike other mollusks, the coleoid cephalopods (octopus, cuttlefish, and squid) possess highly developed nervous systems with huge brains equivalent in size to some vertebrate brains. Cephalopod intelligence is also exhibited by their impressive memory and learning abilities. Why have cephalopods developed such huge brains and cognitive ability? One of the keys to answering this question lies in understanding the social interactions of cephalopods, which have thus far not been well documented. In this paper, I will outline our recent behavioral experiments using mirrors with some cephalopods and discuss these experiments in light of the diversity of social and cognitive behaviors of cephalopods.
Article
Heyes’ (1994, Anim. Behav., 97, 909–919; 1995, Anim. Behav., 50, 1533–1542) recent account of chimpanzees’, Pan troglodytes, reactions to mirrors challenged the view that they are capable of recognizing the equivalence between their mirror images and their physical appearance. In particular, she argued that observations that chimpanzees touch surreptitiously placed marks on their faces while in front of mirrors can be explained as an interaction between ambient levels of face touching and procedural artefacts of the anaesthetization and markings of the subjects. Using new analytical techniques, data are reported that falsify the central predictions generated by her account and confirm predictions derived from the self-recognition model.
Article
No abstractCopyright 1997 The Association for the Study of Animal BehaviourCopyright 1997The Association for the Study of Animal Behaviour.
Article
Self-recognition continues to attract attention because of the evidence of a striking difference between the great apes and humans, on the one hand, and all other primates; the former are capable of self recognition,whereas no compelling evidence exists for prosimians, monkeys, or lesser apes. This is inspite of numerous attempts to facilitate mirror self-recognition in other primates. Although all previous attempts to find self-recognition in rhesus macaques have failed, a recent article [Rajala et al., PLoS One9:e12865, 2010] claimed the opposite—that adult male rhesus monkeys did recognize their own image in a mirror. We critically examine this claim, and conclude that the article fails to provide acceptable evidence for self-recognition in rhesus monkeys.
Article
The habituation of tonic immobility in chickens was examined in six studies. It was shown that repeated elicitation of immobility, and not just handling, was responsible for reduced response durations after multiple exposures to manual restraint. Habituation was a function of the number of stimulus presentations and, in addition, proved surprisingly durable, with diminished reactions using lasting at least 2.5 mo. Strain differences were found in the number of trials required to reach a criteria of habituation, and habituation proceeded faster when immobility termination was self-paced as opposed to experimenter induced. Also, massed trials produced robust sensitization effects rather than diminished responsiveness.
Article
Analyzes the psychological properties of an organism's own reflection in a mirror, and discusses methodological problems associated with mirror research. Many organisms are responsive to mirrors, and reflected images are examined in terms of motivational and social stimulus properties which have been found to extend across a wide variety of species. Reinforcing properties of mirrors are interpreted in terms of novel stimulation with social stimulus overtones. Stimulus change and mimicry are 2 of the most prominent characteristics of an organism's mirror image. An animal in front of a mirror is instrumental in producing changes in the behavior of the reflected image, yet most organisms respond to mirrors as if their image represented another animal. In an attempt to conceptualize both the human and animal data, responses to mirrors and dimensionalized into other- and self-directed behaviors. Implications of mirrors for abnormal behavior and psychotherapy are considered. (63 ref.)
Article
Three studies explored kin recognition through olfaction. In Study I, adults (N=22) were tested for ability to identify the odors of themselves; their mother; their father; a sister; a brother; a familiar, unrelated individual; and a stranger. Acquaintances were identified as accurately as biological kin, implicating an association mechanism. However, biological kin were often confused, implicating phenotypic matching. Same-sex kin were confused more than opposite-sex kin, but mainly when same-sex kin had odors of similar intensity. Study II implicated phenotypic matching. Mothers (N=18) could identify their biological children but not their stepchildren. The preadolescent children (N=37) identified their full siblings but not half-siblings or stepsiblings. Thus, olfactory cues may help mediate favoritism of blood relatives. In Study III, mutual olfactory aversion occurred only in the father-daughter and brother-sister nuclear family relationships. Recognition occurred between opposite-sex siblings but not same-sex siblings. Thus, olfaction may help mediate the development of incest avoidance during childhood (the Westermarck effect).
Article
Three priming experiments were conducted to determine how information about the self from different sensory modalities/cognitive domains affects self-face recognition. Being exposed to your body odor, seeing your name, and hearing your name all facilitated self-face recognition in a reaction time task. No similar cross-modal facilitation was found among stimuli from familiar or novel individuals. The finding of a left-hand advantage for self-face recognition was replicated when no primes were presented. These data, along with other recent results suggest the brain processes/represents information about the self in highly integrated ways.
Are horses capable of self-recognition? A pilot study
  • P Baragli
  • E Demeru
  • C Scopa
  • E Palagi
Baragli, P., Demeru, E., Scopa, C., Palagi, E., 2017. Are horses capable of self-recognition? A pilot study. PLoS One 12 (5), e0176717.
Are ants (Hymenoptera, Formicidae) capable of self-recognition?
  • M.-C Cammaerts
  • R Caemmaerts
Cammaerts, M.-C., Caemmaerts, R., 2015. Are ants (Hymenoptera, Formicidae) capable of self-recognition? J. Sci. 5, 521-532.
The Oxford Handbook of the Self
  • G G Gallup
  • J R Anderson
  • S M Platek
Gallup Jr., G.G., Anderson, J.R., Platek, S.M., 2011. Self-recognition. In: Gallagher, S. (Ed.), The Oxford Handbook of the Self. Oxford University Press, New York, pp. 80-110.
Mirror-induced behavior in the magpie (Pica pica): Evidence of self-recognition
  • H Prior
  • A Schwarz
  • O Gunturkun
Prior, H., Schwarz, A., Gunturkun, O., 2008. Mirror-induced behavior in the magpie (Pica pica): Evidence of self-recognition. PLoS Biol. 6, e202. http://dx.doi.org/10.1371/ journalpbio.0060202.