Alex H Taylor

University of Auckland · School of Psychology

Numerous myths and legends across the world have suggested that corvids are intelligent. However, it is only in the last two decades that their cognition has become the subject of serious scientific investigation. Here I review what we currently know about the temporal, social, and physical cognition of this group. I argue that, while the work to d...

One of the mysteries of animal problem-solving is the extent to which animals mentally represent problems in their minds. Humans can imagine both the solution to a problem and the stages along the way [1–3], such as when we plan one or two moves ahead in chess. The extent to which other animals can do the same is far less clear [4–25]. Here, we pre...

One key aspect of domain-general thought is the ability to integrate information across different cognitive domains. Here, we tested whether kea (Nestor notabilis) can use relative quantities when predicting sampling outcomes, and then integrate both physical information about the presence of a barrier, and social information about the biased sampl...

Making inferences from behaviour to cognition is problematic due to a many-to-one mapping problem, in which any one behaviour can be generated by multiple possible cognitive processes. Attempts to cross this inferential gap when comparing human intelligence to that of animals or machines can generate great debate. Here, we discuss the challenges of...

Jealousy may have evolved to protect valuable social bonds from interlopers, but some researchers have suggested that it is linked to self-awareness and theory of mind, leading to claims that it is unique to humans. We presented dogs (N = 18; 11 females; age: M = 4.6 years, SD = 1.9) with situations in which they could observe an out-of-sight socia...

New Zealand’s kea parrot (Nestor notabilis) is a highly neophilic species that is attracted to human settlements and structures. These environments pose several risks to this endangered species, but also pose a management challenge in how to best ensure that a neophilic species is kept away from the allure of ever-changing human environments. One p...

Self-control underlies goal-directed behaviour in humans and other animals. Delayed gratification ‐ a measure of self-control ‐ requires the ability to tolerate delays and/or invest more effort to obtain a reward of higher value over one of lower value, such as food or mates. Social context, in particular, the presence of competitors, may influence...

Studying the prevalence of putatively rare behaviours, such as tool use, is challenging because absence of evidence can arise either from a species’ inability to produce the behaviour or from insufficient research effort. Here, we tackle this challenge by combining crowdsourcing and phylogenetic modelling to approximate actual rates of a rarely obs...

Self-control underlies goal-directed behaviour in humans and other animals. Delayed gratification - a measure of self-control - requires the ability to tolerate a delay and/or invest more effort to obtain a reward of higher value over one of lower value, such as food or mates. Social context, in particular, the presence of competitors, may influenc...

One key aspect of social cognition is the ability to assess the competence of other agents and then use this information to predict future behaviour. Current research shows that humans assess competence in a highly sophisticated manner. Our species is capable of taking third-party, relative observations of agent’s competencies and then using them t...

The nature and evolution of positive emotion is a major question remaining unanswered in science and philosophy. The study of feelings and emotions in humans and animals is dominated by discussion of affective states that have negative valence. Given the clinical and social significance of negative affect, such as depression, it is unsurprising tha...

A cardinal feature of adult cognition is the awareness of our own cognitive struggles and the capacity to draw upon this awareness to offload internal demand into the environment. In this preregistered study conducted in Australia, we investigated whether 3-8-year-olds (N = 72, 36 male, 36 female, mostly White) could self-initiate such an external...

Contrafreeloading—working to access food that could be freely obtained—is rarely exhibited and poorly understood. Based on data from Grey parrots (Psittacus erithacus), researchers proposed a correlation between contrafreeloading and play: that contrafreeloading is more likely when subjects view the task as play. We tested that hypothesis by subjec...

In recent years, increasingly interdisciplinary exchanges have demonstrated how scientific knowledge of captive cognition and behaviour can prove valuable for informing conservation efforts for endangered species. New Zealand’s endemic mountain parrot, the kea (Nestor notabilis), has shown ape-like performance across a range of cognitive tasks, yet...

New Zealand pest control operations commonly deploy toxic sodium fluoroacetate (1080) baits to control introduced mammalian predators and protect vulnerable native fauna, yet the highly intelligent kea (Nestor notabilis) is at risk of mortality following ingestion of toxic baits intended for their protection. We tested the retention of conditioned...

Jumping spiders (Salticidae) use exceptional vision, largely mediated by their forward-facing anterior lateral (AL) and anterior medial (AM) eyes, to pounce on prey from a distance. We evaluated depth perception through the use of 'texture density' (depth estimation through surface texture comparisons, with greater distances having higher textural...

Metacognition plays an essential role in adults’ cognitive offloading decisions. Despite possessing basic metacognitive capacities, however, preschool-aged children often fail to offload effectively. Here, we introduced 3- to 5-year-olds to a novel search task in which they were unlikely to perform optimally across trials without setting external r...

Human psychology and animal cognition have increasingly used virtual stimuli to test cognitive abilities, with the expectation that participants are ‘naive realists’, that is, that they perceive virtual environments as both equivalent and continuous with real-life equivalents. However, there have been no attempts to investigate whether nonhuman sub...

Tooling is associated with complex cognitive abilities, occurring most regularly in large-brained mammals and birds. Among birds, self-care tooling is seemingly rare in the wild, despite several anecdotal reports of this behaviour in captive parrots. Here, we show that Bruce, a disabled parrot lacking his top mandible, deliberately uses pebbles to...

Naïve individuals of some bird species can rapidly solve vertical string-pulling tasks with virtually no errors. This has led to various hypotheses being proposed which suggest that birds mentally simulate the effects of their actions on strings. A competing embodied cognition hypothesis proposes that this behaviour is instead modulated by perceptu...

Behavioural responses to novelty, including fear and subsequent avoidance of novel stimuli, behaviours referred to as neophobia, determine how animals interact with their environment. Neophobia aids in navigating risk and impacts on adaptability and survival. There is variation within and between individuals and species, however, lack of large-scal...

Although several nonhuman animals have the ability to recognize and match templates in computerized tasks, we know little about their ability to recall and then physically manufacture specific features of mental templates. Across three experiments, Goffin cockatoos (Cacatua goffiniana), a species that can use tools in captivity, were exposed to two...

Executive function plays a critical role in regulating behaviour. Behaviour which directs attention towards the correct solution leads to increased executive function performance in children, but it is unknown how other animals respond to such scaffolding behaviour. Dogs were presented with an A-not-B detour task. After learning to go through gap A...

Animals often rely on different sources of information when making decisions about the environment. Here, we assessed whether two jumping spiders (Salticidae), Trite planiceps and Portia fimbriata, take two different sources of information into account when jumping over water, to which they are averse. Specifically, we investigated whether salticid...

Preregistered Methodology for the paper: New Caledonian crows plan for specific future tool use http://dx.doi.org/10.1098/rspb.2020.1490

This video is the supporting information video for the paper: New Caledonian crows flexibly plan for specific future tool use. Data was collected during the field season 2018 in New Caledonia. It shows an individual being tested in a future planning paradigm. Crows are given alternating trials condition 3 and 4, where they see the platform apparatu...

Prior Experience Tool Use Training: To train crows to use a stone as a tool, subjects were first trained to drop stones into the dispenser apparatus by placing small pieces of meat underneath a stone, which was placed on the edge to the opening of the dispenser. The pieces of meat gradually decreased in size and once the crow started pushing the st...

The ability to plan for future events is one of the defining features of human intelligence. Whether non-human animals can plan for specific future situations remains contentious: despite a sustained research effort over the last two decades, there is still no consensus on this question. Here, we show that New Caledonian crows can use tools to plan...

The investigation of prosocial behavior is of particular interest from an evolutionary perspective. Comparisons of prosociality across non-human animal species have, however, so far largely focused on primates, and their interpretation is hampered by the diversity of paradigms and procedures used. Here, we present the first systematic comparison of...

New Caledonian (NC) crow populations have developed complex tools that show suggestive evidence of cumulative change. These tool designs, therefore, appear to be the product of cumulative technological culture (CTC). We suggest that tool-using NC crows offer highly useful data for current debates over the necessary and sufficient conditions for the...

New Caledonian crows are a key model species for testing whether the ability to reason about unobservable causal mechanisms is unique to humans. Here, I review the growing body of evidence for the absence of this ability in this species.

Macphail famously criticized two foundational assumptions that underlie the evolutionary approach to comparative psychology: that there are differences in intelligence across species, and that intelligent behavior in animals is based on more than associative learning. Here, we provide evidence from recent work in avian cognition that supports both...

In adult humans, decisions involving the choice and use of tools for future events typically require episodic foresight. Previous studies suggest some non-human species are capable of future planning; however, these experiments often cannot fully exclude alternative learning explanations. Here, we used a novel tool-use paradigm aiming to address th...

The ability to make profitable decisions in natural foraging contexts may be influenced by an additional requirement of tool-use, due to increased levels of relational complexity and additional work-effort imposed by tool-use, compared with simply choosing between an immediate and delayed food item. We examined the flexibility for making the most p...

Contagious yawning has been suggested to be a potential signal of empathy in non-human animals. However, few studies have been able to robustly test this claim. Here, we ran a Bayesian multilevel reanalysis of six studies of contagious yawning in dogs. This provided robust support for claims that contagious yawning is present in dogs, but found no...

The presence of pictures of eyes reduces antisocial behaviour in humans. It has been suggested that this ‘watching-eye’ effect is the result of a uniquely human sensitivity to reputation-management cues. However, an alternative explanation is that humans are less likely to carry out risky behaviour in general when they feel like they are being watc...

Self-control underlies cognitive abilities such as decision making and future planning. Delay of gratification is a measure of self-control and involves obtaining a more valuable outcome in the future by tolerating a delay or investing a greater effort in the present. Contextual issues, such as reward visibility and type, may influence delayed grat...

The ability to represent both the identity and trajectory of hidden objects underlies our capacity to reason about causal mechanisms. However, to date no studies have shown that non-human animals are capable of representing these two factors simultaneously. Here, we tested whether kea can represent out-of-sight object trajectories and identities by...

Allogrooming in primates serves not only a hygienic function, but also plays a crucial role in maintaining strong affiliative bonds between group members, which in turn, underpin the emergence of cooperative behavior. In contrast, although allopreening occurs in many avian species, we know little about its social functions. Our study addresses this...

Prosocial behaviour is widespread in humans, but evidence for its occurrence in other species is mixed. We presented a parrot species, the kea (Nestor notabilis) with a series of experiments to test whether they exhibit prosocial tendencies. Across the first round of testing, in our first condition, two of the four kea acted prosocially, as they pr...

Are complex, species-specific behaviors in animals reinforced by material reward alone or do they also induce positive emotions? Many adaptive human behaviors are intrinsically motivated: they not only improve our material outcomes, but improve our affect as well [1-8]. Work to date on animal optimism, as an indicator of positive affect, has genera...

The ability to make profitable decisions in natural foraging contexts may be influenced by an additional requirement of tool-use, due to increased levels of relational complexity and additional work-effort imposed by tool-use, compared with simply choosing between an immediate and delayed food item. We examined the flexibility for making the most p...

Interconnection of behaviors is a process that describes how independently acquired behavioral repertoires can be combined together as a new sequence of behaviors. Manipulations of training, training context and experience of failure in the test situation can hinder this interconnection of previously acquired behaviors. We tested whether wild New C...

A correction to this article has been published and is linked from the HTML and PDF versions of this paper. The error has been fixed in the paper.

Data S1. Data on the Training Stages and Three Experiments, Related to Figures 1–3

Humans use a variety of cues to infer an object's weight, including how easily objects can be moved. For example, if we observe an object being blown down the street by the wind, we can infer that it is light. Here, we tested whether New Caledonian crows make this type of inference. After training that only one type of object (either light or heavy...

Cumulative cultural evolution occurs when social traditions accumulate improvements over time. In humans cumulative cultural evolution is thought to depend on a unique suite of cognitive abilities, including teaching, language and imitation. Tool-making New Caledonian crows show some hallmarks of cumulative culture; but this claim is contentious, i...

A range of non-human animals frequently manipulate and explore objects in their environment, which may enable them to learn about physical properties and potentially form more abstract concepts of properties such as weight and rigidity. Whether animals can apply the information learned during their exploration to solve novel problems, however, and...

Supplementary Methods and Results: Function and Flexibility of Object Exploration in Kea and New Caledonian Crows

Across two different contexts, Kabadayi and Osvath found that ravens preferentially selected items that could be used to obtain future rewards. Do these results demand a rethink of the evolution of flexible planning, or are there leaner alternative explanations for the performance of ravens?

Aesop’s Fable tasks—in which subjects drop objects into a water-filled tube to raise the water level and obtain out-of-reach floating rewards —have been used to test for causal understanding of water displacement in both young children and non-human animals. However, a number of alternative explanations for success on these tasks have yet to be rul...

Aesop’s Fable tasks—in which subjects drop objects into a water-filled tube to raise the water level and obtain out-of-reach floating rewards —have been used to test for causal understanding of water displacement in both young children and non-human animals. However, a number of alternative explanations for success on these tasks have yet to be rul...

Correct choices (%) in each condition per year group P-values (‘p’) are calculated from exact two-tailed binomial tests. Significant p-values are highlighted in bold. NS, not significant with a Bonferroni correction.

Video of example trials Supplementary movie of the example trials

Raw data

Correct choices (%) in each condition across all subjects (n = 55). P-values (‘p’) are calculated from exact two-tailed binomial tests. Significant p-values are highlighted in bold.

It has been suggested that inequity aversion is a mechanism that evolved in humans to maximize the pay-offs from engaging in cooperative tasks and to foster long-term cooperative relationships between unrelated individuals. In support of this, evidence of inequity aversion in nonhuman animals has typically been found in species that, like humans, l...

Cooperation between individuals is one of the defining features of our species. While other animals, such as chimpanzees, elephants, coral trout and rooks also exhibit cooperative behaviours, it is not clear if they think about cooperation in the same way as humans do. In this study we presented the kea, a parrot endemic to New Zealand, with a seri...

Examples of kea performances across the experiment. (3GP)

New Caledonian crows have demonstrated flexible behaviour when using tools and solving novel problems. However, we do not know whether this flexibility extends to tool manufacture. Here, we show that these crows respond to different tool-using problems by altering the length of the tools that they manufacture; on average, crows made shorter tools f...

It is highly difficult to pinpoint what is going through an animal’s mind when it appears to solve a problem by ‘insight’. Here, we searched for an information processing error during the emergence of seemingly insightful stone dropping in New Caledonian crows. We presented these birds with the platform apparatus, where a heavy object needs to be d...

Data set for the birds’ preferences and interactions with the heavy and light blocks. (XLSX)

Example of the weight inattention error. Video clip showing D4R showing the weight inattention error. The subject initially drops a light block into the apparatus (which is too light to collapse the platform) before dropping in a heavy block and causing the platform to collapse. (3GP)

The ability to reason about causality underlies key aspects of human cognition, but the extent to which non-humans understand causality is still largely unknown. The Aesop’s Fable paradigm, where objects are inserted into water-filled tubes to obtain out-of-reach rewards, has been used to test casual reasoning in birds and children. However, succes...

Children Experiment 1A results per age group and test group. Group 1: initial preference for sinking objects and Group 2: trained preference for floating object. (PDF)

Crow trial-by-trial performance. (XLSX)

Children Experiment 1B results per age group and test group. Group 1: initial preference for hollow objects and Group 2: no post-test object preference. (PDF)

Child selection trial-by-trial performance. (XLSX)