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Humans learn by observing the behaviour of others, which can lead to more efficient problem-solving than by trial-and-error learning. Numerous studies have shown that animals, other than humans, are also capable of social learning. Dogs, as humans' closest companion animals, can learn to obtain rewards following behavioural demonstrations by humans. However, it is not known whether cats, who also live with humans, can learn how to solve problems by observing human behaviours. Three experiments were used to investigate whether cats could change their behaviour and gain rewards efficiently by observing a human demonstrating how to obtain food. In Experiment 1, a human demonstrated how to open a transparent drawer and take out the reward inside, but cats did not significantly follow the same method as the human. In Experiment 2a, a transparent tube device was used to make the operation easier for cats. However, cats were not influenced by the human behaviour. As the devices used in these experiments were transparent, meaning that the cats could see the food inside directly, they might have required strong inhibitory control. Therefore, in Experiment 2b the tube device was made opaque, and cats again observed the human demonstration. Nevertheless, the cats were not influenced by the human's behaviour. The results of these experiments indicate a lack of social learning, including imitation, from human behaviours in cats, at least in these experimental settings with food rewards. Other than their inherent ability, cats' biological characteristics and the experimental context may have contributed towards the negative results.

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Dogs are highly sensitive to human behavior, and they evaluate us using both their direct experiences and from a third-party perspective. Dogs pay attention to various aspects of our actions and make judgments about, for example, social vs. selfish acts. However, it is unclear if dogs judge human competence. To investigate this issue, we showed dogs two experimenters manipulating a transparent container: one was good at removing the lid to take an object out of the container (Competent person), whereas the other was unsuccessful at this task (Incompetent person). After demonstrating their actions twice with different containers, both experimenters simultaneously tried to open a third container which contained food (Food condition; 30 dogs) or was empty (Empty condition; 30 dogs). Dogs in the Food condition looked at the Competent person longer than the Incompetent one, and female dogs in particular were more likely to approach the Competent person. In contrast, dogs in the Empty condition showed no preferences. This result suggests that dogs can recognize different competence levels in humans, and that this ability influences their behavior according to the first situation. Our data also indicate that more attention should be given to potential sex differences in dogs' social evaluation abilities.

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Humans communicate with each other through language, which enables us talk about things beyond time and space. Do non-human animals learn to associate human speech with specific objects in everyday life? We examined whether cats matched familiar cats' names and faces (Exp.1) and human family members' names and faces (Exp.2). Cats were presented with a photo of the familiar cat's face on a laptop monitor after hearing the same cat's name or another cat's name called by the subject cat's owner (Exp.1) or an experimenter (Exp.2). Half of the trials were in a congruent condition where the name and face matched, and half were in an incongruent (mismatch) condition. Results of Exp.1 showed that household cats paid attention to the monitor for longer in the incongruent condition, suggesting an expectancy violation effect; however, café cats did not. In Exp.2, cats living in larger human families were found to look at the monitor for increasingly longer durations in the incongruent condition. Furthermore, this tendency was stronger among cats that had lived with their human family for a longer time, although we could not rule out an effect of age. This study provides evidence that cats link a companion's name and corresponding face without explicit training.

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Many animals probably hold mental representations about the whereabouts of others; this is a form of socio-spatial cognition. We tested whether cats mentally map the spatial position of their owner or a familiar cat to the source of the owner's or familiar cat's vocalization. In Experiment 1, we placed one speaker outside a familiar room (speaker 1) and another (speaker 2) inside the room, as far as possible from speaker 1, then we left the subject alone in the room. In the habituation phase, the cat heard its owner's voice calling its name five times from speaker 1. In the test phase, shortly after the 5th habituation phase vocalization, one of the two speakers played either the owner's voice or a stranger's voice calling the cat's name once. There were four test combinations of speaker location and sound: SamesoundSamelocation, SamesoundDifflocation, DiffsoundSamelocation, DiffsoundDifflocation. In line with our prediction, cats showed most surprise in the SamesoundDifflocation condition, where the owner suddenly seemed to be in a new place. This reaction disappeared when we used cat vocalizations (Experiment 2) or non-vocal sounds (Experiment 3) as the auditory stimuli. Our results suggest that cats have mental representations about their out-of-sight owner linked to hearing the owner's voice, indicating a previously unidentified socio-spatial cognitive ability.

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We investigated if and how Syrian hamsters (Mesocricetus auratus) show flexibility in their use of multiple sources of information in a spatial learning task. In Experiment 1, hamsters were trained to exit an arena through one of three doors. The goal, marked by a beacon, was fixed during the training phase. When the beacon was placed nearer to another door, the hamsters predominantly chose the original door rather than those with the relocated beacon (Tests A and C). The removal of the beacon had little effect on their performance (Test B). In Experiment 2, when we changed the shape of the apparatus to make the positional information of the goals other than the beacon invalid, a few individual subjects used the beacon (Test B'). However, after experiencing the invalidity of such positional information, the original door was less frequently chosen in a rerun of the beacon relocation test (Test C). Finally, in Experiment 3, we confirmed that hamsters could easily learn to use the beacon when it was the sole cue for navigation. These results suggest that, despite hamsters' limited tendency to use a beacon for navigation, they can flexibly use multiple strategies depending on their experience or environmental context. (PsycInfo Database Record (c) 2021 APA, all rights reserved).

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Altruism is often considered as the ultimate form of prosociality and is defined as any act that benefits others without direct benefit to the actor. Many nonhuman species have been reported to express different forms of altruism, although their expression in experimental studies is highly dependent on the paradigm used. Tufted capuchin monkeys are one of the most studied species; however, the evidence for altruism in this species remains inconclusive. This study aimed to investigate whether two paradigms, adapted from those in which great apes have shown altruism, could be useful for revealing signs of altruistic capabilities in capuchins. Pairs of monkeys were tested in two experiments involving a similar mechanism but with different costs to acting altruistically. The first used a more costly operant sharing task in which an operator could unlock a door to allow a recipient to enter the room and share his food. The second consisted of a less costly helping task, in which the operator's food was secured but he could help the recipient to get other food that was in a locked container. The results suggest that capuchins, although apparently unwilling to share their food in a costly operant situation, might altruistically help selected recipients, in response to requesting by the latter. While our small sample size along with procedural limitations preclude firm conclusions, we discuss how further ameliorations of our tasks could further contribute to the study of altruistic capacities in primates.

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Although it has been proposed that birds acquire visual depth cues through dynamic head movements, behavioral evidence on how birds use motion parallax depth cues caused by self-motion is lacking. This study investigated whether self-generated motion parallax modulates pecking motor control and visual size perception in pigeons (Columba livia). We trained pigeons to peck a target on a touch monitor and to classify it as small or large. To manipulate motion parallax of the target, we changed the target position on the monitor according to the bird's head position in real time using a custom-built head tracker with two cameras. Pecking motor control was affected by the manipulation of motion parallax: when the motion parallax signified the target position farther than the monitor surface, the head position just before pecking to target was near the monitor surface, and vice versa. By contrast, motion parallax did not affect how the pigeons classified target sizes, implying that motion parallax might not contribute to size constancy in pigeons. These results indicate that motion parallax via head movements modulates pecking motor control in pigeons, suggesting that head movements of pigeons have the visual function of accessing motion parallax depth cues.

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Dogs and cats are sensitive to human social signals such as pointing, gazing and facial expressions. Previous studies have demonstrated that dogs show over-reliance on human actions in the presence of conflicting physical cues. However, it is still unclear whether this tendency is specific to dogs, or shared with other domesticated animals. Here, we compared the behavior of dogs and cats in a two-choice task after they saw a person taking and pretending to eat food from a baited container. After one experimenter showed the dogs (Experiment 1) or cats (Experiment 2) two opaque containers, each containing a piece of the food, another (the demonstrator) removed food from one container and ate it (Eating condition), or simply picked up the food and returned it to the container (Showing condition). We recorded which container the subjects approached first after the demonstration. Both dogs and cats were less likely to choose the container associated with the human in the Eating than the Showing condition, although choice for this container was above chance in both conditions. In Experiment 3, we confirmed that dogs and cats naturally chose a baited over an empty container. These results suggest that both species' reasoning abilities might be influenced by a bias for prioritizing specific human actions. Although dogs and cats have different domestication histories, their social awareness of humans appears similar, possibly because they both share their environment with humans.

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Humans have mental time in our mind, apart from physical time that is a part of system that governs the physical world, and memory is our key cognitive ability for recognizing the passage of time. Recent studies have suggested that the memory system of several nonhuman animals may have an incidental nature, which is also a feature of episodic memory. In addition, apes, which are phylogenetically close to humans, have an ability to remember a single past event. In the case of humans, preverbal infants under the age of two are able to retain long-term memory of a single event and apply it to predict a future event. Thus, nonhuman animals and preverbal human infants both have their own specific mental time travel abilities, and there is a phylogenetic and ontogenic basis of full-fledged mental time travel that can be found in human adults.

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Transitive inference (TI) is the ability to infer unknown relationships from previous information. To test TI in non-human animals, transitive responding has been examined in a TI task where non-adjacent pairs were presented after premise pair training. Some mammals, birds and paper wasps can pass TI tasks. Although previous studies showed that some fish are capable of TI in the social context, it remains unclear whether fish can pass TI task. Here, we conducted a TI task in cleaner wrasses (Labroides dimidiatus), which interact with various client fishes and conspecifics. Because they make decisions based on previous direct and indirect interactions in the context of cleaning interactions, we predicted that the ability of TI is beneficial for cleaner fish. Four tested fish were trained with four pairs of visual stimuli in a 5-term series: A-B+, B-C+, C-D+, and D-E+ (plus and minus denote rewards and non-rewards, respectively). After training, a novel pair, BD (BD test), was presented wherein the fish chose D more frequently than B. In contrast, reinforcement history did not predict the choice D. Our results suggest that cleaner fish passed the TI task, similar to mammals and birds. Although the mechanism underlying transitive responding in cleaner fish remains unclear, this work contributes to understanding cognitive abilities in fish.

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The fact that squirrel monkeys do not routinely cooperate in the wild has been proposed to explain their failure to show disadvantageous inequity aversion (i.e., negative reactions when receiving less than a partner) in an experimental exchange. Here we assessed whether the use of a tray-pulling paradigm, allowing for a larger variety of unequal testing situations, would bring additional insights into inequity aversion in this species. Squirrel monkeys were tested in pairs in which only the donor could pull a tray baited with food to within reach of itself and a recipient. Using pairs with different social relationships, we examined donors' frequencies of pulling both in the presence and absence of a recipient, as well as across three different food distributions: equal, qualitative inequity (higher-value reward for the recipient), and quantitative inequity (no food reward for the donor). Results showed that female donors pulled the tray less often in the quantitative inequity condition with an out-group female recipient than when alone. However, such discrimination was not observed when females were with female in-group and male out-group recipients. By contrast, male donors did not adjust their pull frequencies according to the recipient's presence or identity (female and male out-group recipients). These results point towards possible disadvantageous inequity aversion in female squirrel monkeys. However, alternative hypotheses such as increased arousal caused by out-group female recipients cannot be ruled out. We discuss the data in line with major theories of inequity aversion and cooperation in primates.

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Depth information is necessary for perceiving the real size of objects at varying visual distances. To investigate to what extent this size constancy present in another vertebrate class, we addressed the two questions using pigeons: (a) whether pigeons see a corridor illusion based on size constancy and (b) whether pigeons prioritize pictorial cues over motion parallax cues for size constancy, like humans. We trained pigeons to classify target sizes on a corridor. In addition, we presented a dynamic version of corridor illusion in which the target and corridor moved side by side. Target speed was changed to manipulate motion parallax. With the static corridor, pigeons overestimated the target size when it was located higher, indicating that pigeons see a corridor illusion like humans. With the dynamic corridor, the pigeons overestimated the target size depending on target position, as in the static condition, but target speed did not affect their responses, indicating that the pictorial precedence also applies to pigeons. In a follow-up experiment using the same stimulus, we confirmed that humans perceive object size based on pictorial cues. These results suggest that size constancy characteristics are highly similar between pigeons and humans, despite the differences in their phylogeny and neural systems.

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Integrating local motion signals detected by the primary motion detector is crucial for representing a rigid, two-dimensional motion. The nature of motion integration has been studied using stimuli consisting of two superimposed sinusoidal gratings of different orientations, called plaid motion, and it has been shown that humans perceive integrated motion in the direction where the component constraint lines are intersected. We previously found that pigeons and humans perceive different movement directions from plaid motion; pigeons responded to the vector average direction of the gratings. Although this suggests that the underlying processes of motion integration differ between the two species, the viewing distance in the pigeon experiment, which used a touch panel procedure, was much smaller than in typical human experiments. The current study investigated the potential effect of viewing distance on the perception of plaid motion in pigeons. We trained six pigeons to detect whether motion directions were tilted leftward or rightward while a visual display was presented 0 or 40 cm from an operant chamber. The pigeons responded to plaid stimuli for both viewing distance conditions as if they perceived motion in the vector average direction of two-component gratings. The result indicates that the species difference in plaid perception is not an artefact of viewing distance and suggests that pigeons use a different strategy than humans for integrating visual motion.

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Human adults often envisage future events and prepare items or information in advance. Studies have shown that young children can also prepare items for upcoming events, but little is known about their ability to prepare information for such events. Here, we used nonverbal measures, which are widely used in comparative cognitive research, to ask whether children seek information for their future knowledge states or events. In Experiment 1, 4- and 5-year-olds had to find a sticker located under an opaque or transparent cup. The children could observe by peeking while an experimenter placed the sticker for the trial. We found that 5-year-olds peeked for longer in the opaque than the transparent condition but 4-year-olds did not. In Experiment 2, 5- and 6-year-olds had to find stickers in 2 rooms; in 1 room, an actor hid a sticker under 1 of 5 opaque cups, whereas in the other room, another actor placed a sticker under 1 of 5 transparent cups. Children could observe what the actors were doing via a monitor and then choose a room in which to search. Children of both age-groups watched events in the opaque-cup room longer than the transparent-cup room in the first trial. These results suggest that at least 5-year-olds can collect appropriate information for a future task. Our procedure should be easily adaptable for a range of nonhuman species. Studies using this procedure might reveal the phylogenetic distribution of this metacognitive ability. (PsycInfo Database Record (c) 2020 APA, all rights reserved).

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Memory is always vulnerable to loss because it fades over time. To avoid the potential loss of a particular memory, individuals who can anticipate this loss might seek an opportunity to re-encode the information at the later point. Evidence shows that animals engage in online memory monitoring, but few studies have addressed whether they seek information prospectively to guard against potential forgetting. In the present study, to address this issue three capuchin monkeys were tested using a delayed matching-to-sample task with a cue signaling delay length (short or long). In the tests, subjects could choose at the onset of the delay whether or not to seek a re-presentation of a sample after the delay. Results showed that two monkeys sought re-presentation in the long delay more frequently than in the short delay, suggesting knowledge of the necessity of re-presentation based on knowing the length of the delay. However, further tests provided no evidence that this response was based on metacognitive cues. Whether capuchin monkeys are capable of prospective information-seeking for own potential forgetting remains to be established.

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Perceiving motion is a fundamental ability for animals. Primates integrate local 1D motion across orientation and space to compute a rigid 2D motion. It is unknown whether the rule of 2D motion integration is universal within the vertebrate clade; comparative studies of animals with different ecological backgrounds from primates may help answer that question. Here we investigated 2D motion integration in pigeons, using hierarchically structured motion stimuli, namely a barber-pole illusion and plaid motion. The pigeons were trained to report the direction of motion of random dots. When a barber-pole or plaid stimulus was presented, they reported the direction perpendicular to the grating orientation for barber-pole and the vector average of two component gratings for plaid motion. These results demonstrate that pigeons perceive different directions than humans from the same motion stimuli, and suggest that the 2D integrating rules in the primate brain has been elaborated through phylogenetic or ecological factors specific to the clade.

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Across various species, infant faces share various features referred to as "baby schema"(Lorenz, 1942). Assuming that these features are indeed shared among species, it is possible that nonhuman animals may perceive age information in conspecific and heterospecific faces. We tested whether tufted capuchin monkeys (Sapajus apella) would visually categorize age from faces. In Experiment 1, we trained 4 monkeys to discriminate adult and infant faces of conspecifics using a symbolic matching-to-sample procedure. We then tested whether their categorization transferred to faces of other species (i.e., dogs and humans). In Experiment 2, we trained another 2 monkeys on age categorization of heterospecific (human) faces and tested them with conspecific and dog faces, to assess whether conspecific age categorization in Experiment 1 was specific. In Experiment 3, the 4 monkeys from Experiment 1 were trained with human faces, whereas the 2 monkeys from Experiment 2 were trained with conspecific faces; we then tested all 6 monkeys with faces of dogs and other species including New World monkeys, Old World monkeys, apes, and carnivores. During training, the monkeys quickly learned to categorize adult and infant faces of both conspecifics and humans. However, age categorization failed to transfer to different species in the test phase in all 3 experiments. (PsycINFO Database Record (c) 2019 APA, all rights reserved).

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We examined whether cats have a cross-modal representation of humans, using a cross-modal expectancy violation paradigm originally used with dogs by Adachi et al. (Anim Cogn 10:17-21, 2007). We compared cats living in houses and in cat cafés to assess the potential effect of postnatal experience. Cats were presented with the face of either their owner or a stranger on a laptop monitor after playing back the voice of one of two people calling the subject's name. In half of the trials the voice and face were of the same person (congruent condition) whereas in the other half of trials the stimuli did not match (incongruent condition). The café cats paid attention to the monitor longer in incongruent than congruent conditions, showing an expectancy violation. By contrast, house cats showed no similar tendency. These results show that at least café cats can predict their owner's face upon hearing the owner's voice, suggesting possession of cross-modal representation of at least one human. There may be a minimal kind or amount of postnatal experiences that lead to formation of a cross-modal representation of a specific person.

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[Correction Notice: An Erratum for this article was reported online in Journal of Comparative Psychology on May 9 2019 (see record 2019-35064-001). Reports several errors in errors in the article: the descriptions of conditions in the Discussion section were incorrect, the number of decimal places for some statistical values was greater, the participants' names were swapped in Tables 1, 2, 3, and 4, and the labels indicating trial types in Figures 3 and 4 were swapped and so did not correctly match the data. All versions of this article have been corrected.] Flexibly changing information processing based on required cognitive resources allows adaptation in terms of cognitive parsimony. Several species have been shown to use temporal durations between memory acquisition and retrieval as a cue for memory-controlling and to engage selectively in active memorization in situations involving lower cognitive cost. However, few studies have addressed whether signaling delay length at different stages of memory affects memorization differently. In the present study with tufted capuchin monkeys (Sapajus apella), we added visual cues signaling upcoming delay length to a delayed matching-to-sample task, so that the monkeys were informed about how long information should be maintained at different points during with-sample or after-sample conditions. We investigated whether the monkeys changed their information processing depending on their expectation of the upcoming delay length and on whether encoding was controllable (4 s vs. 16 s, Experiment 1). The results indicate that two monkeys showed different patterns depending on whether encoding was controllable, whereas the third monkey never changed her strategy. The following experiment using shorter delays showed that one monkey showed a similar pattern across experiments, providing robust evidence for cognitive flexibility in accordance with relative task difficulty (1 s vs. 8 s, Experiment 2). Overall, our results suggest that capuchins adopt two kinds of strategies depending on the experimental context, that is, expending fewer resources on relatively difficult trials and/or maintaining their processing style irrespective of delays. Their strategies aiming at saving cognitive costs may reflect a psychological function to control memory formation either prospectively or retrospectively. (PsycINFO Database Record (c) 2019 APA, all rights reserved).

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