Are dogs indeed susceptible to Kanizsa's triangle illusion?

Survival often depends on the ability of the visual system to process information accurately; thus, research demonstrating that a brain is susceptible to optical illusions is of considerable interest, particularly when the experiments involve phylogenetic comparisons. Are Lõoke et al.'s (Anim. Cogn, 25:43-51, 2022) data strong enough to allow the inclusion of dogs on the list of nonhumans that can perceive illusory Kanizsa figures?

Comments on "Intra- and interspecific variation in self-control capacities of parrots in a delay of gratification task".

Brucks (Anim Cogn 25(2):473-491, 2021) have published an intriguing paper on the differing abilities of various species of parrots to succeed in a delay of gratification task. I find their interspecies comparisons of considerable interest but take exception to their misrepresentation of prior research on delayed gratification from our laboratory in Koepke (J Comp Psychol 129:339-346, 2015). Contrary to their claims, our subject was never trained on the task; rather, one might argue instead that all their subjects received considerable training or at least forms of pre-exposure that could affect their overall claims. I also briefly discuss other design features that may have affected their results.

Implications of wild cockatoos manufacturing and using tools.

O'Hara et al. (Current Biology, 31, 4512-4520, 2021) show that wild Goffin's cockatoos (Cacatua goffiniana) exhibit tool-related abilities at levels previously demonstrated by nonhuman primates or, in birds, only by those raised in captivity. Their data provide information about the cognitive and ecological underpinnings of this behavior and provide the impetus to search for additional examples of convergent evolution in avian and mammalian lines.

Does captivity alter problem-solving behavior in Goffin's cockatoos?

Researchers often argue for the existence of "captivity bias": a higher success rate that may be observed for nonhumans tested in captivity compared to those tested in nature, purportedly because the former have certain advantages that the latter lack. Rössler et al. (Scientific Reports 10, 8681, 2020) find that, at least for Goffin's cockatoos (Cacatua goffiniana), differences exist in motivation, not in problem-solving ability.

Tool use in Goffin's cockatoos: Shape/frame matching.

Nonhuman tool use is no longer questioned; the issues now are whether such use is mostly inflexible and innately specified or involves experience, innovation, adaptation, and cognitive planning, and how many species qualify. Habl and Auersperg (PLoS One, 12(11):e0186859, 2017) have shown that some Goffin's cockatoos (Cacatua goffiniana) respond in novel ways to a tool-use task that nonhuman primates and young children find somewhat challenging.

"Birdbrains" should not be ignored in studying the evolution of g.

The authors evaluate evidence for general intelligence (g) in nonhumans but lean heavily toward mammalian data. They mention, but do not discuss in detail, evidence for g in nonmammalian species, for which substantive material exists. I refer to a number of avian studies, particularly in corvids and parrots, which would add breadth to the material presented in the target article.

Human-Grey parrot (Psittacus erithacus) reciprocity: a follow-up study.

In a previous study (Péron et al. in Anim Cogn, doi: 10.1007/s10071-012.05640 , 2012), Grey parrots, working in dyads, took turns choosing one of four differently coloured cups with differing outcomes: empty (null, non-rewarding), selfish (keeping reward for oneself), share (sharing a divisible reward), or giving (donating reward to other). When the dyads involved three humans with different specific intentions (selfish, giving, or copying the bird's behaviour), birds' responses only tended towards consistency with human behaviour. Our dominant bird was willing to share a reward with a human who was willing to give up her reward, was selfish with the selfish human, and tended towards sharing with the copycat human; our subordinate bird tended slightly towards increased sharing with the generous human and selfishness with the selfish human, but did not clearly mirror the behaviour of the copycat. We theorized that the birds' inability to understand the copycat condition fully-that they could potentially maximize reward by choosing to share-was a consequence of their viewing the copycat's behaviour as erratic compared with the consistently selfish or giving humans and thus not realizing that they were indeed being mirrored. We suggested that copycat trials subsequently be performed as a separate experiment, without being contrasted with trials in which humans acted consistently, in order to determine if results might have differed. We have now performed that experiment, and shown that at least one Grey parrot--our dominant--responded in a manner suggesting that he deduced the appropriate contingencies.

A study of executive function in grey parrots (Psittacus erithacus): Experience can affect delay of gratification.

Executive function (EF) involves several abilities often correlated with success in various aspects of human life. Similar skills could also be advantageous to nonhumans, but few studies have effectively examined the extent of their EF abilities. Studies have also examined what experiences might strengthen/weaken human EF; might specific experiences also affect nonhuman EF? One type of EF often tested in both humans and nonhumans involves a delay of gratification-the ability to forgo an immediate reward to gain one either better in quality or quantity. We compared how Grey parrots (Psittacus erithacus) with somewhat different experimental histories performed when required to wait for more food-a difficult task for avian species. One laboratory-raised parrot, Griffin, had previously succeeded when asked to wait for a better reward and on other tasks purportedly involving some level of EF skills but failed to wait for a larger reward. After succeeding on a task designed to improve impulse control, he consistently waited for a larger reward, more nuts, for up to 15 min-far longer than most avian species tested. Two other parrots, Pepper and Franco, companion animals, had had no experience with delayed gratification tasks, but were as successful as Griffin on other EF-related studies in which they participated. These birds, with different histories than Griffin, also waited for more food for longer periods than most other birds, though not as consistently as Griffin. We suggest that specific types of experiences may strengthen EF in Grey parrots. (PsycInfo Database Record (c) 2024 APA, all rights reserved).

A study of sharing and reciprocity in grey parrots (Psittacus erithacus).

Demonstrations of nonhuman ability to share resources and reciprocate such sharing seem contingent upon the experimental paradigm used (note Horner et al. in PNAS 108:13847-13851, 2011). Here, such behaviour in Grey parrots (Psittacus erithacus) was tested in two experiments, both designed to avoid possible issues involving apparatus complexity, visible reward options, and physical competition and/or limited communication between subjects. In both studies, two birds, working in dyads, took turns in choosing one of four different coloured cups with differing outcomes: empty (null, nonrewarding), selfish (keeping reward for oneself), share (sharing a divisible reward), or giving (donating reward to other). In Experiment 1, each bird alternated choices with a conspecific; in Experiment 2, each bird alternated with the three humans with different specific intentions (selfish, giving, or copying bird's behaviour). In both experiments, birds could learn to cooperatively reward a partner at little cost to themselves-by sharing-and potentially maximize overall reward by reciprocating such sharing. Experiment 1 results differed depending upon which bird began a session: Only our dominant bird, as follower, was willing to share. In Experiment 2, birds' responses tended towards consistency with human behaviour. Our dominant bird was willing to share a reward with a human who was willing to give up her reward, was selfish with the selfish human, and tended towards sharing with the copycat human; our subordinate bird tended slightly towards increased sharing with the generous human and selfishness with the selfish human, but did not change behaviour with the copycat.

Exploring the utility of robots as distractors during a delay-of-gratification task in preschool children.

The development of executive function (EF) in children, particularly with respect to self-regulation skills, has been linked to long-term benefits in terms of social and health outcomes. One such skill is the ability to deal with frustrations when waiting for a delayed, preferred reward. Although robots have increasingly been utilized in educational situations that involve teaching psychosocial skills to children, including various aspects related to self-control, the utility of robots in increasing the likelihood of self-imposed delay of gratification remains to be explored. Using a single-case experimental design, the present study exposed 24 preschoolers to three experimental conditions where a choice was provided between an immediately available reward and a delayed but larger reward. The likelihood of waiting increased over sessions when children were simply asked to wait, but waiting times did not increase further during a condition where teachers offered activities as a distraction. However, when children were exposed to robots and given the opportunity to interact with them, waiting times for the majority of children increased with medium to large effect sizes. Given the positive implications of strong executive function, how it might be increased in children in which it is lacking, limited, or in the process of developing, is of considerable import. This study highlights the effectiveness of robots as a distractor during waiting times and outlines a potential new application of robots in educational contexts.

Further evidence for addition and numerical competence by a Grey parrot (Psittacus erithacus).

A Grey parrot (Psittacus erithacus), able to quantify sets of eight or fewer items (including heterogeneous subsets), to sum two sequentially presented sets of 0­6 items (up to 6), and to identify and serially order Arabic numerals (1­8), all by using English labels (Pepperberg in J Comp Psychol 108:36­44, 1994; J CompPsychol 120:1­11, 2006a; J Comp Psychol 120:205­216,2006b; Pepperberg and Carey submitted), was tested on addition of two Arabic numerals or three sequentially presented collections (e.g., of variously sized jelly beans or nuts). He was, without explicit training and in the absence of the previously viewed addends, asked, "How many total?" and required to answer with a vocal English number label. In a few trials on the Arabic numeral addition, he was also shown variously colored Arabic numerals while the addends were hidden and asked "What color number (is the) total?" Although his death precluded testing on all possible arrays, his accuracy was statistically significant and suggested addition abilities comparable with those of nonhuman primates.

Delayed gratification: A grey parrot (Psittacus erithacus) will wait for more tokens.

Delay of gratification, the ability to forgo an immediate reward and wait to gain a reward better in either quality or quantity, has been used as a metric for temporal discounting, self-control, and the ability to plan for the future in both humans (particularly children) and nonhumans. Several avian species have been able to wait for a better quality reward for up to 15 min, but none seem able to wait for a better quantity reward for any significant period of time. Using a token system (where each wooden heart represents 1 nut piece), we demonstrated that a Grey parrot-who had previously waited up to 15 min for better quality-would now wait for better quantity, again for up to 15 min. Thus, symbolic distancing-that is, removal of the immediate presence of the hedonic item-enabled him to perform at levels comparable with young children on the classic test and might be a viable method for training executive function. (PsycInfo Database Record (c) 2022 APA, all rights reserved).

Contrafreeloading in kea (Nestor notabilis) in comparison to Grey parrots (Psittacus erithacus).

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 subjecting a relatively more playful parrot species, the kea (Nestor notabilis), to the same experimental tasks. Experiment 1 presented eight kea with container pairs holding more- or less-preferred free or enclosed food items, and examined three types of contrafreeloading: calculated (working to access preferred food over less-preferred, freely available food); classic (working to access food identical to freely available food); and super (working to access less-preferred food over preferred, freely available food). At the group level, the kea behaved similarly to the Greys: They significantly preferred calculated contrafreeloading, performed classic contrafreeloading at chance, and significantly failed to super contrafreeload. However, overall kea engaged in more contrafreeloading than Greys. Experiment 2 examined a potentially more ecologically relevant task, a choice between shelled and unshelled walnuts. No kea contrafreeloaded for nuts, whereas two of five Greys significantly preferred nut contrafreeloading and one chose at chance. We examine proximate and adaptive explanations for the performances of these differentially playful parrot species to further elucidate the role of play in contrafreeloading.

A Review of the Model/Rival (M/R) Technique for Training Interspecies Communication and Its Use in Behavioral Research.

In this paper, I will review the Model/Rival (M/R) technique that has been used to establish interspecies communication with Grey parrots (Psittacus erithacus). I will describe the original format developed by Todt, the relationship to other forms of observational learning outlined by other researchers, and the adaptations that I devised. I will describe how my undergraduate trainers and I isolated the various components that constitute the technique and explain how each is necessary, but how only the combination of all components is sufficient for successful implementation-and how improper implementation can lead to failure. I will briefly summarize the results of proper implementation-including the importance of interspecies communication itself as a technique for studying animal cognition.

Nonhuman and Nonhuman-Human Communication: Some Issues and Questions.

Deciphering nonhuman communication - particularly nonhuman vocal communication - has been a longstanding human quest. We are, for example, fascinated by the songs of birds and whales, the grunts of apes, the barks of dogs, and the croaks of frogs; we wonder about their potential meaning and their relationship to human language. Do these utterances express little more than emotional states, or do they convey actual bits and bytes of concrete information? Humans' numerous attempts to decipher nonhuman systems have, however, progressed slowly. We still wonder why only a small number of species are capable of vocal learning, a trait that, because it allows for innovation and adaptation, would seem to be a prerequisite for most language-like abilities. Humans have also attempted to teach nonhumans elements of our system, using both vocal and nonvocal systems. The rationale for such training is that the extent of success in instilling symbolic reference provides some evidence for, at the very least, the cognitive underpinnings of parallels between human and nonhuman communication systems. However, separating acquisition of reference from simple object-label association is not a simple matter, as reference begins with such associations, and the point at which true reference emerges is not always obvious. I begin by discussing these points and questions, predominantly from the viewpoint of someone studying avian abilities. I end by examining the question posed by Premack: do nonhumans that have achieved some level of symbolic reference then process information differently from those that have not? I suggest the answer is likely "yes," giving examples from my research on Grey parrots (Psittacus erithacus).

Initial evidence for eliciting contrafreeloading in grey parrots (Psittacus erithacus) via the opportunity for playful foraging.

Contrafreeloading is the choice to perform a physical task to access food over freely available food, a behavior pattern contrary to the predictions of both optimal foraging and learning theories. This study examined the presence and degree of contrafreeloading in Grey parrots (Psittacus erithacus) and the possible interpretation of such behavior in the context of play. Experiment 1 presented 4 subjects, Griffin, Athena, Franco and Pepper, with container pairs holding more- or less-preferred free or enclosed food items. Degrees of contrafreeloading were classified as follows: calculated contrafreeloading (working to access preferred food over less-preferred, freely available food); classic contrafreeloading (working to access food equal in value to freely available food); and super contrafreeloading (working to access a less-preferred food over preferred, freely available food). Of these three, Griffin significantly preferred classic and calculated contrafreeloading; Athena, Pepper, and Franco significantly preferred calculated contrafreeloading. Experiment 2 examined a more ecologically relevant contrafreeloading task in 5 parrots, Griffin, Athena, Lucci, Pepper, and Franco, using shelled and unshelled nuts. Athena and Franco significantly preferred cracking the shell to obtain the nut (contrafreeloading); Griffin and Lucci did not; Pepper chose at chance. We examine numerous possible explanations for their behavior and suggest that individual differences in contrafreeloading among the Grey parrots could relate to which task each considers some form of play. (PsycInfo Database Record (c) 2021 APA, all rights reserved).

The Comparative Psychology of Intelligence: Some Thirty Years Later.

After re-reading Macphail's (1987) essay "The Comparative Psychology of Intelligence" with all the associated commentaries, I was struck by how contemporary many of the arguments and counter-arguments still appear. Of course, we now know much more about the abilities of many more species (including their neurobiology) and fewer researchers currently favor explanations of behavior based solely on associative processes; however, the role of contextual variables in comparative psychology still remains cloudy. I discuss these issues briefly. Given my research interests involving the cognitive and communicative abilities of Grey parrots, the one aspect of the original article upon which I feel I can comment in depth involves Macphail's claims about the importance of language-and specifically syntax-in problem-solving and thus in placing humans above all other creatures. Granted, no other species has (or in my opinion is likely ever to acquire) everything that goes into what is considered "human language." Nevertheless, several other species have acquired symbolic representation, and considerable information now exists upon which to base an argument that such acquisition by itself enables more complex and "human-like" cognitive processes. Such processes may form the basis of the kind of intelligence that is measured-not surprisingly-with human-based tasks, including the use of such representations as a means to directly query non-human subjects in ways not unlike those used with young children.

Age and Species Comparisons of Visual Mental Manipulation Ability as Evidence for its Development and Evolution.

Intelligent behavior is shaped by the abilities to store and manipulate information in visual working memory. Although humans and various non-human animals demonstrate similar storage capacities, the evolution of manipulation ability remains relatively unspecified. To what extent are manipulation limits unique to humans versus shared across species? Here, we compare behavioral signatures of manipulation ability demonstrated by human adults and 6-to-8-year-old children with that of an animal separated from humans by over 300 million years of evolution: a Grey parrot (Psittacus erithacus). All groups of participants completed a variant of the "Shell Game", which required mentally updating the locations of varying set sizes of occluded objects that swapped places a number of times. The parrot not only demonstrated above-chance performance, but also outperformed children across all conditions. Indeed, the parrot's accuracy was comparable to (and slightly better than) human adults' over 12/14 set-size/number-of-swaps combinations, until four items were manipulated with 3-4 swaps, where performance decreased toward that of 6- to 8-year-olds. These results suggest that manipulation of visual working memory representations is an evolutionarily ancient ability. An important next step in this research program is establishing variability across species, and identifying the evolutionary origins (analogous or homologous) of manipulation mechanisms.

Piagetian liquid overconservation in grey parrots (Psittacus erithacus).

Piagetian liquid overconservation was investigated in four grey parrots (Psittacus erithacus). Birds tracked the larger of two quantities that had undergone various manipulations. Experiment 1 involved controls to ensure birds could track movement of the quantities, including direct and diagonal cross-transfers. All birds succeeded. In Experiment 2, different amounts in the same transparent or opaque containers were transferred into containers rigged such that amounts then looked equal. All birds chose the larger amounts after transformation when initial cups were transparent, but were random or had consistent side preferences when initial cups were opaque (thus obscuring quantity differences), showing that they used inferential, not perceptual, information, and that no extraneous cues existed. In Experiment 3, two birds saw different amounts from same-sized transparent or opaque containers transferred to containers of different sizes, rigged such that resultant amounts appeared to fill both cups and in which lesser amounts appeared greater on some trials. The older bird demonstrated full use of inferential abilities; he succeeded in all tasks when initial cups were transparent but, again, had consistent side preferences with initially opaque cups. The younger succeeded in the direct transfers with transparent initial cups but was random or showed a side preference on diagonal-transfer tasks and on all the tasks with opaque initial cups. However, she had no preference for the cup that appeared fuller, suggesting she did not use perceptual cues. Overall, grey parrots appear to understand the constancy of liquids undergoing physical transformation. (PsycInfo Database Record (c) 2020 APA, all rights reserved).

Initial evidence for probabilistic reasoning in a grey parrot (Psittacus erithacus).

Research has shown that some forms of inferential reasoning are likely widespread throughout the animal kingdom (e.g., exclusion, in which a subject infers the placement of a reward by eliminating potential alternative sites), but other types of inferential tasks have not been extensively tested. We examined whether a nonhuman might succeed in an experiment based on probabilistic reasoning, specifically, the ability to make inferences about a sample based on information about a population. A Grey parrot (Psittacus erithacus), previously trained to use English labels referentially to identify objects, observed a human researcher deposit 2 different types of items in a 3:1 ratio (e.g., 3 corks and 1 piece of paper) into an opaque bucket. One item was then randomly withdrawn while hidden from the parrot's view. When asked to identify the still-hidden object, the parrot's vocal responses tracked this 3:1 ratio over a large number of trials. Some levels of probabilistic reasoning therefore are not limited to humans, nonhuman primates, or even mammals. (PsycINFO Database Record