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In all human cultures, people gesture iconically. However, the evolutionary basis of iconic gestures is unknown. In this study, chimpanzees and bonobos, and 2- and 3-year-old children, learned how to operate two apparatuses to get rewards. Then, at test, only a human adult had access to the apparatuses, and participants could instruct her about how to obtain the rewards. Children frequently produced appropriate iconic gestures, but with the exception of one human-raised chimpanzee, great apes did not gesture iconically. However, chimpanzees pointed to a reward outside the apparatus in another experimental condition, showing their motivation and ability to communicate with the human to request it. They also manipulated a duplicate apparatus in appropriate ways, though it was unclear if they did this to communicate with the human. Although great apes may have some of the prerequisite skills involved, iconic gestures come naturally to humans in a way that they do not for great apes.

Recent research suggests that witnessing events of fission (e.g., the splitting of a solid object) impairs human infants', human adults', and non-human primates' object representations. The present studies investigated the reactions of gorillas and orangutans to cohesion violation across different types of fission events implementing a behavioral paradigm previously used with human infants. Results suggest that fission events vary in their impact on representational abilities but do not destroy apes' representations of continuously existing objects. (Contains 5 figures.)

Four bonobos, seven gorillas, and six orangutans were presented with two small rectangular boards on a platform. One of the boards had a piece of food under it so that it acquired an inclined orientation whereas the other remained flat on the platform. Subjects preferentially selected the inclined board. In another experiment, subjects were initially presented with two inclined boards and a transformation took place in which one of the boards fell flat to the platform while the other remained inclined. Subjects also preferred the board that remained inclined. Two additional experiments highlighted some of the possible limitations of their reasoning in this task. Presented with two inclined boards, one of which was visibly supported by a piece of wood, they failed to systematically select the unsupported one whose only reason for being inclined was the presence of the reward. Another experiment presented two rewards in each trial (instead of the customary one) in one of the following two combinations: large banana vs. small carrot or small banana vs. large carrot. Prior to the test, E presented both rewards to the subject and then hid each of them under one of the boards so that both boards were differentially inclined due to the different sizes of the rewards involved. Although subjects selected the board that showed a greater inclination (thus securing the larger reward), they disregarded the type of food that was involved. This often meant that they chose the large carrot over the small banana even though they reversed such a choice when the rewards were not occluded by the boards. Providing subjects with a "reminder" of the type of reward hidden under the boards did not alter the original results. There was no evidence of learning throughout the various experiments and control tests ruled out the possibility of inadvertent cuing by the experimenter, poor performance due to a lack of motivation, or good performance due to a predisposition to select objects with sloped surfaces. It is concluded that subjects made some inferences about the reason for the inclined orientation of the boards, and not simply associated an inclined orientation with the presence of the reward.

The study investigates what an intermediate success rate means in bonobos, chimpanzees, and orangutans. Apes participated in liquid conservation experiments where they had to track the larger of two different quantities of juice after various kinds of transformations [Suda, C., & Call, J. (2004). Piagetian liquid conservation in the great apes (Pan paniscus, Pan troglodytes, and Pongo pygmaeus). Journal of Comparative Psychology, 118, 265-279). When making a decision, apes sometimes demonstrated hesitant behavior, concurrently pointing to both alternatives or successively changing their choice. Moderately successful apes showed more hesitation than highly successful or unsuccessful apes. The results are consistent with the cognitive conflict model: The experiments created a higher degree of cognitive conflict on moderately successful apes than on very successful or unsuccessful apes. This indicates that an intermediate performance reflects the joint operation and potential conflict between two different cognitive strategies (identity and appearance) inherent to the Piagetian conservation task.

Compared comprehension of novel communicative signs to assist 2.5- and 3-year-old humans, chimpanzees, and orangutans find hidden objects during a hiding-finding game. Found that children at both ages performed above chance with all signs. No ape performed above chance for any signs not known before the experiment despite three times as many trials as the children. (Author)

Primate cognition research is reliant on access to members of the study sp ecies and logistical infrastructures to conduct observations and experiments. Historically founded in research centers and private collections, and spreading to modern zoos, sanctuaries, and the field, primate cognition has been investigated in diverse settings, each with benefits and challenges. In our systematic review of 12 primatology, animal behavior, and animal cognition journals over the last 15 years, we turn a spotlight on zoos to quantify their current impact on the field and to highlight their potential as robust contributors to future work. To put zoo‐based research in context, we compare zoos to three other site types: university‐owned or independent research centers, sanctuaries, and field sites. We assess the contributions of zoos across several critical considerations in primate cognition research, including number of investigations, species diversity, sample size, research topic diversity, and methodology. We identified 1119 publications reporting studies of primate cognition, almost 25% of which report research conducted in zoos. Across publications, zoo‐based research has greater species diversity than research centers and covers a diverse range of research topics. Although our review is merely a snapshot of primate cognition research, our findings suggest that zoos may present advantages to researchers regarding species diversity, and lack some of the methodological constraints of field sites, allowing greater ease of access to a diverse range of subjects for cognition investigations. We suggest that zoos have great potential as key contributors for future investigations in primate cognition. Finally, we shed light on the symbiotic relationship that can emerge between researchers and zoos, forming partnerships that bring unique advantages to both parties. Highlights: Zoo‐based research contributes ~25% of publications in primate cognitionZoos offer high species diversity in cognitive researchResearch in zoos encompasses a wide and balanced array of topics within primate cognition [ABSTRACT FROM AUTHOR]

To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.anbehav.2007.04.018 Byline: Jana Uher, Jens B. Asendorpf, Josep Call Abstract: Using a multidisciplinary approach, the present study complements ethological behaviour measurements with basic theoretical concepts, methods and approaches of the personality psychological trait paradigm. Its adoptability and usefulness for animal studies are tested exemplarily on a sample of 20 zoo-housed great apes (five of each of the following species): bonobos, Pan paniscus; chimpanzees, Pan troglodytes verus; gorillas, Gorilla gorilla gorilla; and orang-utans, Pongo pygmaeus abelii. Data on 76 single trait-relevant behaviours were recorded in a series of 14 laboratory-based situations and in two different group situations. Data collection was repeated completely after a break of 2 weeks within a 50-day period. All behaviour records were sufficiently reliable. Individual- and variable-oriented analyses showed high/substantial temporal stability on different levels of aggregation. Distinctive and stable individual situational and response profiles clarified the importance of situations and of multiple trait-relevant behaviours. The present study calls for a closer collaboration between behavioural biologists and personality psychologists to tap the full potential of animal personality research. Author Affiliation: (a) Humboldt-University Berlin, Institute for Psychology, Germany (a ) Max Planck Institute for Evolutionary Anthropology, Germany Article History: Received 22 June 2006; Revised 5 March 2007; Accepted 17 April 2007 Article Note: (miscellaneous) MS. number: 9010R2

Making economic decisions in a natural foraging situation that involves the use of tools may require an animal to consider more levels of relational complexity than merely deciding between an immediate and a delayed food option. We used the same method previously used with Goffin´s cockatoos to investigate the orangutans’ flexibility for making the most profitable decisions when confronted with five different settings that included one or two different apparatuses, two different tools and two food items (one more preferred than the other). We found that orangutans made profitable decisions relative to reward quality, when the task required the subjects to select a tool over an immediately accessible food reward. Furthermore, most subjects were sensitive to work-effort when the immediate and the delayed option (directly accessible by using a tool) led to the same outcome. Most subjects continued to make profitable decisions that required taking into account the tool functionality. In a final multidimensional task design in which subjects had to simultaneously focus on two apparatuses, two reward qualities and two different tools, the orangutans chose the functional tool to access the high quality reward. [ABSTRACT FROM AUTHOR]

Social primates can influence others through the control of resources. For instance, dominant male chimpanzees might allow subordinates access to mate with females in exchange for social support. However, little is known about how chimpanzees strategically use a position of leverage to maximize their own benefits. We address this question by presenting dyads of captive chimpanzee (N = 6) with a task resulting in an unequal reward distribution. To gain the higher reward each individual should wait for their partner to act. In addition, one participant had leverage: access to an alternative secure reward. By varying the presence and value of the leverage we tested whether individuals used it strategically (e.g. by waiting longer for partners to act when they had leverage in the form of alternatives). Additionally, non-social controls served to show if chimpanzees understood the social dilemma. We measured the likelihood to choose the leverage and their latencies to act. The final decision made by the chimpanzees did not differ as a function of condition (test versus non-social control) or the value of the leverage, but they did wait longer to act when the leverage was smaller—particularly in test (versus non-social control) trials suggesting that they understood the conflict of interest involved. The chimpanzees thus recognized the existence of social leverage, but did not use it strategically to maximize their rewards. [ABSTRACT FROM AUTHOR]

Cognitive abilities cannot be measured directly. What we can measure is individual variation in task performance. In this paper, we first make the case for why we should be interested in mapping individual differences in task performance onto particular cognitive abilities: we suggest that it is crucial for examining the causes and consequences of variation both within and between species. As a case study, we examine whether multiple measures of inhibitory control for non-human animals do indeed produce correlated task performance; however, no clear pattern emerges that would support the notion of a common cognitive ability underpinning individual differences in performance. We advocate a psychometric approach involving a threestep programme to make theoretical and empirical progress: first, we need tasks that reveal signature limits in performance. Second, we need to assess the reliability of individual differences in task performance. Third, multi-trait multi-method test batteries will be instrumental in validating cognitive abilities. Together, these steps will help us to establish what varies between individuals that could impact their fitness and ultimately shape the course of the evolution of animal minds. Finally, we propose executive functions, including working memory, inhibitory control and attentional shifting, as a sensible starting point for this endeavour. [ABSTRACT FROM AUTHOR]

Cetaceans are remarkable for exhibiting group-specific behavioral traditions or cultures in several behavioral domains (e.g., calls, behavioral tactics), and the question of whether they can be acquired socially, for example through imitative processes, remains open. Here we used a “Do as other does” paradigm to experimentally study the ability of a beluga to imitate familiar intransitive (body-oriented) actions demonstrated by a conspecific. The participant was first trained to copy three familiar behaviors on command (training phase) and then was tested for her ability to generalize the learned “Do as the other does” command to a different set of three familiar behaviors (testing phase). We found that the beluga (1) was capable of learning the copy command signal “Do what-the-other-does”; (2) exhibited high matching accuracy for trained behaviors (mean = 84% of correct performance) after making the first successful copy on command; (3) copied successfully the new set of three familiar generalization behaviors that were untrained to the copy command (range of first copy = 12 to 35 trials); and (4) deployed a high level of matching accuracy (mean = 83%) after making the first copy of an untrained behavior on command. This is the first evidence of contextual imitation of intransitive (body-oriented) movements in the beluga and adds to the reported findings on production imitation of sounds in this species and production imitation of sounds and motor actions in several cetaceans, especially dolphins and killer whales. Collectively these findings highlight the notion that cetaceans have a natural propensity at skillfully and proficiently matching the sounds and body movements demonstrated by conspecifics, a fitness-enhancing propensity in the context of cooperative hunting and anti-predatory defense tactics, and of alliance formation strategies that have been documented in these species’ natural habitats. Future work should determine if the beluga can also imitate novel motor actions. [ABSTRACT FROM AUTHOR]

Cooperative hunting is a cognitively challenging activity since individuals have to coordinate movements with a partner and at the same time react to the prey. Domestic dogs evolved from wolves, who engage in cooperative hunting regularly, but it is not clear whether dogs have kept their cooperative hunting skills. We presented pairs of dogs with a reward behind a fence with two openings in it. A sliding door operated by the experimenter could block one opening but not both simultaneously. The dogs needed to coordinate their actions, so that each was in front of a different opening, if one of them was to cross through and get food. All 24 dog pairs solved the problem. In study 1, we demonstrated that dogs understood how the apparatus worked. In study 2, we found that, although the performance of the pairs did not depend on the divisibility of the reward, pairs were quicker at coordinating their actions when both anticipated rewards. However, the dogs did not monitor one another, suggesting that their solutions were achieved by each individual attempting to maximize for itself. [ABSTRACT FROM AUTHOR]

Comparative experimental studies of imitative learning have focused mainly on primates and birds. However, cetaceans are promising candidates to display imitative learning as they have evolved in socioecological settings that have selected for large brains, complex sociality, and coordinated predatory tactics. Here we tested imitative learning in killer whales, Orcinus orca. We used a 'do-as-other-does' paradigm in which 3 subjects witnessed a conspecific demonstrator's performance that included 15 familiar and 4 novel behaviours. The three subjects (1) learned the copy command signal 'Do that' very quickly, that is, 20 trials on average; (2) copied 100 % of the demonstrator's familiar and novel actions; (3) achieved full matches in the first attempt for 8-13 familiar behaviours (out of 15) and for the 2 novel behaviours (out of 2) in one subject; and (4) took no longer than 8 trials to accurately copy any familiar behaviour, and no longer than 16 trials to copy any novel behaviour. This study provides experimental evidence for body imitation, including production imitation, in killer whales that is comparable to that observed in dolphins tested under similar conditions. These findings suggest that imitative learning may underpin some of the group-specific traditions reported in killer whales in the field. [ABSTRACT FROM AUTHOR]

In previous studies claiming to demonstrate that great apes understand the goals of others, the apes could potentially have been using subtle behavioral cues present during the test to succeed. In the current studies, we ruled out the use of such cues by making the behavior of the experimenter identical in the test phase of both the experimental and control conditions; the only difference was the preceding 'context.' In the first study, apes interpreted a human's ambiguous action as having the underlying goal of opening a box, or not, based on that human's previous actions with similar boxes. In the second study, chimpanzees learned that when a human stood up she was going to go get food for them, but when a novel, unexpected event happened, they changed their expectation-presumably based on their understanding that this new event led the human to change her goal. These studies suggest that great apes do not need concurrent behavioral cues to infer others' goals, but can do so from a variety of different types of cues-even cues displaced in time. [ABSTRACT FROM AUTHOR]

We examined whether eight capuchins and eight chimpanzees were able to retrieve a reward placed inside a tube, of varying length, by selecting the correct stick from different sets of three sticks differing in length (functional feature) and handle (non-functional feature). Moreover, to investigate whether seeing the stick inside the tube (visual feedback) improves performance, half of the subjects were tested with a transparent apparatus and the other half with an opaque apparatus. Phase 1 included (a) Training 1 in which each stick had a different handle and (b) Transfer 1 in which the handles were switched among sticks, so that the functional tool had the same length but a different handle than before. The seven chimpanzees and one capuchin that passed Transfer 1 received Transfer 2. The other subjects received (a) Training 2, which used the same sticks from Phase 1 with handles switched in every trial, and (b) Transfer 2 in which the tube was longer, all sticks had the same new handle, and the formerly longest tool became intermediate in length. Eight chimpanzees and three capuchins passed Transfer 2. Results showed that (1) chimpanzees applied relational structures in tool using tasks more quickly than capuchins and (2) capuchins required more varied experience to attend to the functional feature of the tool. Interestingly, visual feedback did not improve performance in either species. [ABSTRACT FROM AUTHOR]

We investigated whether chimpanzees, bonobos, and orangutans encoded the location of a reward hidden underneath one of three identical cups in relation to (1) the other cups in the array-i.e., the relative position of the baited cup within the array; or (2) the landmarks surrounding the cups-e.g., the edge of the table. Apes witnessed the hiding of a food reward under one of three cups forming a straight line on a platform. After 30 s, they were allowed to search for the reward. In three different experiments, we varied the distance of the cups to the edge of the platform and the distance between the cups. Results showed that both manipulated variables affected apes' retrieval accuracy. Subjects' retrieval accuracy was higher for the outer cups compared with the Middle cup, especially if the outer cups were located next to the platform's edge. Additionally, the larger the distance between the cups, the better performance became. [ABSTRACT FROM AUTHOR]

Despite current interest in dog (Canisfamiliaris) cognition, very little is known about how dogs represent objects and how they compare with other species, such as the great apes. Therefore, we investigated how dogs and great apes (chimpanzees [Pan troglodytes], bonobos [Pan paniscus], orangutans [Pongo pygmaeus], gorillas [Gorilla gorilla]) individuate objects in a classical violation of expectation paradigm. We used a container (magic cup) with a double bottom that allowed us to change the type of food that subjects had seen being placed in the container. Using a 2 X 2 design, we varied whether subjects received a generally preferred food and whether the food was substituted (surprise trials) or not (baseline trials). Apes showed increased begging and looking behaviors and dogs showed increased smelling behavior. Both species stayed near the experimenter more frequently in the surprise trials compared with baseline trials. Both species reacted to positive (i.e., good food substituted for bad food) and negative (i.e., bad food substituted for good food) surprises. These results suggest that apes and dogs were able to individuate objects according to their properties or type in comparable ways. In addition, we looked for frustration and elation effects, but subjects' behaviors were not influenced by the food they saw and which they received in previous trials. [ABSTRACT FROM AUTHOR]

Ape species-specific communication is grounded on the present, possesses some referential qualities and is mostly used to request objects or actions from others. Artificial systems of communication borrowed from humans transform apes' communicative exchanges by freeing them from the present (i.e. displaced reference) although requests still predominate as the main reason for communicating with others. Symbol use appears to enhance apes' relational abilities and their inhibitory control. Despite these substantial changes, it is concluded that even though artificial communication enhances thought and enables its expression more openly, it does not create it or modify the motivation behind communicative exchanges. [ABSTRACT FROM AUTHOR]

Differences in cognitive skills across taxa, and between monkeys and apes in particular, have been explained by different hypotheses, although these often are not supported by systematic interspecific comparisons. Here, we directly compared the cognitive performance of the four great apes and three monkey species (spider monkeys, capuchin monkeys, and long-tailed macaques), differing in their phylogenetic-relatedness and socioecology. We tested subjects on their ability to remember object locations (memory task), track object displacements (transposition task), and obtain out-of-reach rewards (support task). Our results showed no support for an overall clear-cut distinction in cognitive skills between monkeys and apes as species performance varied substantially across tasks. Although we found differences in performance at tracking object displacements between monkeys and apes, interspecific differences in the other two tasks were better explained in terms of differential socioecology, especially differential levels of fission-fusion dynamics. A cluster analysis using mean scores of each condition of the three tasks for each species suggested that the only dichotomy might be between members of the genus Pan and the rest of the tested species. These findings evidence the importance of using multiple tasks across multiple species in a comparative perspective to test different explanations for the enhancement of specific cognitive skills. [ABSTRACT FROM AUTHOR]

Abstract: Recent research suggests that witnessing events of fission (e.g., the splitting of a solid object) impairs human infants’, human adults’, and non-human primates’ object representations. The present studies investigated the reactions of gorillas and orangutans to cohesion violation across different types of fission events implementing a behavioral paradigm previously used with human infants. Results suggest that fission events vary in their impact on representational abilities but do not destroy apes’ representations of continuously existing objects. [Copyright &y& Elsevier]

While bonobos and chimpanzees are both genetically and behaviorally very similar, they also differ in significant ways. Bonobos are more cautious and socially tolerant while chimpanzees are more dependent on extractive foraging, which requires tools. The similarities suggest the two species should be cognitively similar while the behavioral differences predict where the two species should differ cognitively. We compared both species on a wide range of cognitive problems testing their understanding of the physical and social world. Bonobos were more skilled at solving tasks related to theory of mind or an understanding of social causality, while chimpanzees were more skilled at tasks requiring the use of tools and an understanding of physical causality. These species differences support the role of ecological and socio-ecological pressures in shaping cognitive skills over relatively short periods of evolutionary time. [ABSTRACT FROM AUTHOR]

Chimpanzee (Pan troglodytes) agonistic screams are graded vocal signals that are produced in a context-specific manner. Screams given by aggressors and victims can be discriminated based on their acoustic structure but the mechanisms of listener comprehension of these calls are currently unknown. In this study, we show that chimpanzees extract social information from these vocal signals that, combined with their more general social knowledge, enables them to understand the nature of out-of-sight social interactions. In playback experiments, we broadcast congruent and incongruent sequences of agonistic calls and monitored the response of bystanders. Congruent sequences were in accordance with existing social dominance relations; incongruent ones violated them. Subjects looked significantly longer at incongruent sequences, despite them being acoustically less salient (fewer call types from fewer individuals) than congruent ones. We concluded that chimpanzees categorised an apparently simple acoustic signal into victim and aggressor screams and used pragmatics to form inferences about third-party interactions they could not see. [ABSTRACT FROM AUTHOR]

We investigated dogs' ability to take the visual perspective of humans. In the main study, each of two toys was placed on the dog's side of two small barriers (one opaque, one transparent). In experimental conditions, a human sat on the opposite side of the barriers, such that she could see only the toy behind the transparent barrier. The experimenter then told the dog to 'Bring it here!' (without designating either toy in any way). In the Back Turned control E also sat on the opposite side but with her back turned so that she could see neither toy, and in the Same Side control she sat on the same side as the dog such that she could see both toys. When toys were differentiable dogs approached the toy behind the transparent barrier in experimental as compared to back turned and same side condition. Dogs did not differentiate between the two control conditions. In a second study dogs were not sensitive to what a human had or had not seen in the immediate past. These results suggest that, even in the absence of overt behavioural cues, dogs are sensitive to others visual access, even if that differs from their own. [ABSTRACT FROM AUTHOR]

The article provides information on a study that provided evidence of design complexity in one of the termite-fishing tools of chimpanzees (Pan troglodytes) in the Goualougo Triangle, Republic of Congo by adopting the approach taken with New Caledonian crows (Corvus moneduloides). It describes the study site and tool used in termite predation. Experimental trials were conducted comparing the effectiveness of brush-tipped probe and an unmodified fishing probe in gathering insects. The study concluded that chimpanzees in the Congo Basin have developed an improve fishing probe design.

Boesch (2007) criticizes research comparing ape and human cognition on the basis of both internal and external validity. The authors show here that most of those criticisms are not valid because: (i) most threats to internal validity (e.g., conspecific experimenters for humans but not apes) are controlled for experimentally; (ii) externally, there is no empirical evidence that captive apes have fewer cognitive skills than wild apes and indeed some evidence (especially from human-raised apes) that they have more; and (iii) externally, there is no empirical evidence that Western middle-class children have different cognitive skills from other children at very early ages in basic cognitive domains. Although difficult, with appropriate methodological care, experimental cross-species comparisons may be validly made. [ABSTRACT FROM AUTHOR]

G. Gergely, H. Bekkering, and I. Király (2002) showed that 14-month-old infants imitate rationally, copying an adult’s unusual action more often when it was freely chosen than when it was forced by some constraint. This suggests that infants understand others’ intentions as rational choices of action plans. It is important to test whether apes also understand others’ intentions in this way. In each of the current 3 studies, a comparison group of 14-month-olds used a tool more often when a demonstrator freely chose to use it than when she had to use it, but apes generally used the tool equally often in both conditions (orangutans were an exception). Only some apes thus show an understanding of others’ intentions as rational choices of action plans. [ABSTRACT FROM AUTHOR]

We investigated whether two dogs that had been specially trained to retrieve objects by their names were able to integrate information about the identity ( What) as well as the location ( Where) of those objects so that they could plan their search accordingly. In a first study, two sets of objects were placed in two separate rooms and subjects were asked to retrieve the objects, one after the other. Both dogs remembered the identity of the objects as they reliably retrieved the correct objects. One of the dogs was also able to integrate information about the object’s location as he chose the correct location in which the object had been placed. Further investigation of the second dog’s behavior revealed that she followed a more stereotyped search strategy. Despite this variation in performance, this study provides evidence for the memory of What and Where in a domestic dog and shows the prospective use of such information in a search task. [ABSTRACT FROM AUTHOR]

Chimpanzee’s perspective-taking abilities are currently disputed. Here we show that in some food competition contexts, subordinate chimpanzees do take the visual perspective of dominant individuals, preferentially targeting a hidden piece of the food that the dominant cannot see over a piece that is visible to both individuals. However, the space where the animals compete is critical in determining whether subjects demonstrate this skill. We suggest that competition intensity, as mediated by these spatial factors, may play an important role in determining the strategy chimpanzees utilize in competitive contexts. Since some strategies may not require visual perspective taking in order to be successful, chimpanzees may not always demonstrate this skill. Differences in spatial arrangement may therefore account for the conflicting results of past studies. [ABSTRACT FROM AUTHOR]

Problem solving often relies on generating new responses while inhibiting others, particularly prepotent ones. A paradigm to study inhibitory abilities is the reverse contingency task (Boysen and Berntson in J Exp Psychol Anim Behav Process 21:82–86, ), in which two different quantities of food are offered to an individual who receives the array he did not choose. Therefore, mastery of the task demands selecting the smaller quantity to obtain the larger one. Several non-human primates have been tested in the reverse contingency task. To date, only great apes and rhesus monkeys ( Macaca mulatta) have succeeded in the original task, with no need of procedural modifications as the large-or-none contingency, correction trials or symbolic stimuli substituting for actual food quantities. Here, four mangabeys were presented with two stimulus arrays of one and four raisins in the context of the reverse contingency task. Three of them learned to perform the task well above chance without a modified procedure. They also reached above-chance performance when presented with two stimulus arrays of zero and four raisins, despite the initial difficulty of choosing a null quantity. After a period of 7–10 months, in which the animals were not tested on any task, all three subjects continued to perform well, even when presented with novel quantity pairs. [ABSTRACT FROM AUTHOR]

Previous research has shown that many social animals follow the gaze of other individuals. However, knowledge about how this skill differs between species and whether it shows a relationship with genetic distance from humans is still fragmentary. In the present study of gaze following in great apes, we manipulated the nature of a visual obstruction and the presence/absence of a target. We found that bonobos, chimpanzees, and gorillas followed gaze significantly more often when the obstruction had a window than when it did not, just as human infants do. Additionally, bonobos and chimpanzees looked at the experimenter's side of a windowless obstruction more often than the other species. Moreover, bonobos produced more double looks when the barrier was opaque than when it had a window, indicating an understanding of what other individuals see. The most distant human relatives studied, orangutans, showed few signs of understanding what another individual saw. Instead, they were attracted to the target's location by the target's presence, but not by the experimenter's gaze. Great apes' perspective-taking skills seem to have increased in the evolutionary lineage leading to bonobos, chimpanzees, and humans. [ABSTRACT FROM AUTHOR]

The present study aimed to test what bonobos (Pan paniscus) understand about contact. The task consisted of a clear horizontal tube containing a piece of food and a stick with a disk attached. The bonobos chose which side to push or pull the stick for the disk to contact the food and make it accessible. There were 9 variations in tube design, which differed in the positions of the stick, disk, and food. All 5 bonobos passed at least 1 configuration. A recent study (A. E. Helme, N. S. Clayton, & N. J. Emery, 2006) found that rooks could learn only tube configurations that provided an asymmetrical stick cue, whereas bonobos did not demonstrate an understanding of contact but showed more individual variation, attending to the positions of the food, disk, and stick. [ABSTRACT FROM AUTHOR]

Abstract: The study investigates what an intermediate success rate means in bonobos, chimpanzees, and orangutans. Apes participated in liquid conservation experiments where they had to track the larger of two different quantities of juice after various kinds of transformations [Suda, C., & Call, J. (2004). Piagetian liquid conservation in the great apes (Pan paniscus, Pan troglodytes, and Pongo pygmaeus). Journal of Comparative Psychology, 118, 265–279). When making a decision, apes sometimes demonstrated hesitant behavior, concurrently pointing to both alternatives or successively changing their choice. Moderately successful apes showed more hesitation than highly successful or unsuccessful apes. The results are consistent with the cognitive conflict model: The experiments created a higher degree of cognitive conflict on moderately successful apes than on very successful or unsuccessful apes. This indicates that an intermediate performance reflects the joint operation and potential conflict between two different cognitive strategies (identity and appearance) inherent to the Piagetian conservation task. [Copyright &y& Elsevier]

Dogs can use the placement of an arbitrary marker to locate hidden food in an object-choice situation. We tested domestic dogs ( Canis familiaris) in three studies aimed at pinning down the relative contributions of the human’s hand and the marker itself. We baited one of two cups (outside of the dogs’ view) and gave the dog a communicative cue to find the food. Study 1 systematically varied dogs’ perceptual access to the marker placing event, so that dogs saw either the whole human, the hand only, the marker only, or nothing. Follow-up trials investigated the effect of removing the marker before the dog’s choice. Dogs used the marker as a communicative cue even when it had been removed prior to the dog’s choice and attached more importance to this cue than to the hand that placed it although the presence of the hand boosted performance when it appeared together with the marker. Study 2 directly contrasted the importance of the hand and the marker and revealed that the effect of the marker diminished if it had been associated with both cups. In contrast touching both cups with the hand had no effect on performance. Study 3 investigated whether the means of marker placement (intentional or accidental) had an effect on dogs’ choices. Results showed that dogs did not differentiate intentional and accidental placing of the marker. These results suggest that dogs use the marker as a genuine communicative cue quite independently from the experimenter’s actions. [ABSTRACT FROM AUTHOR]

Two important elements in problem solving are the abilities to encode relevant task features and to combine multiple actions to achieve the goal. The authors investigated these 2 elements in a task in which gorillas (Gorilla gorilla) and orangutans (Pongo pygmaeus) had to use a tool to retrieve an out-of-reach reward. Subjects were able to select tools of an appropriate length to reach the reward even when the position of the reward and tools were not simultaneously visible. When presented with tools that were too short to retrieve the reward, subjects were more likely to refuse to use them than when tools were the appropriate length. Subjects were proficient at using tools in sequence to retrieve the reward. [ABSTRACT FROM AUTHOR]

A previous observational study suggested that when faced with a partner with its back turned, chimpanzees tend to move around to the front of a non-attending partner and then gesture — rather than gesturing once to attract attention and then again to convey a specific intent. We investigated this preference experimentally by presenting six orangutans, five gorillas, nine chimpanzees, and four bonobos with a food begging situation in which we varied the body orientation of an experimenter (E) with respect to the subject (front vs. back) and the location of the food (in front or behind E). These manipulations allowed us to measure whether subjects preferred to move around to face E or to use signals to attract her attention before they begged for food. Results showed that all species moved around to face E and then produced visual gestures, instead of using tactile/ auditory gestures behind E to call her attention. Species differences were apparent particularly when the food and E were in different locations. Unlike gorillas and orangutans, chimpanzees and bonobos (from genus Pan) produced their gestures in front of E in all conditions, including that in which subjects had to leave the food behind to communicate with her. Implications of these results are discussed in the context of the evolution of social cognition in great apes. [ABSTRACT FROM AUTHOR]

A number of animal species have evolved the cognitive ability to detect when they are being watched by other individuals. Precisely what kind of information they use to make this determination is unknown. There is particular controversy in the case of the great apes because different studies report conflicting results. In experiment 1, we presented chimpanzees, orangutans, and bonobos with a situation in which they had to request food from a human observer who was in one of various attentional states. She either stared at the ape, faced the ape with her eyes closed, sat with her back towards the ape, or left the room. In experiment 2, we systematically crossed the observer’s body and face orientation so that the observer could have her body and/or face oriented either towards or away from the subject. Results indicated that apes produced more behaviors when they were being watched. They did this not only on the basis of whether they could see the experimenter as a whole, but they were sensitive to her body and face orientation separately. These results suggest that body and face orientation encode two different types of information. Whereas face orientation encodes the observer’s perceptual access, body orientation encodes the observer’s disposition to transfer food. In contrast to the results on body and face orientation, only two of the tested subjects responded to the state of the observer’s eyes. [ABSTRACT FROM AUTHOR]

Understanding the intentional actions of others is a fundamental part of human social cognition and behavior. An important question is therefore whether other animal species, especially our nearest relatives the chimpanzees, also understand the intentional actions of others. Here we show that chimpanzees spontaneously (without training) behave differently depending on whether a human is unwilling or unable to give them food. Chimpanzees produced more behaviors and left the testing station earlier with an unwilling compared to an unable (but willing) experimenter. These data together with other recent studies on chimpanzees’ knowledge about others’ visual perception show that chimpanzees know more about the intentional actions and perceptions of others than previously demonstrated. [ABSTRACT FROM AUTHOR]

Bonobos (Pan paniscus; n = 4), chimpanzees (Pan troglodytes; n = 12), gorillas (Gorilla gorilla; n = 8), and orangutans (Pongo pygmaeus; n = 6) were presented with 2 cups (1 baited) and given visual or auditory information about their contents. Visual information consisted of letting subjects look inside the cups. Auditory information consisted of shaking the cup so that the baited cup produced a rattling sound. Subjects correctly selected the baited cup both when they saw or heard the food. Nine individuals were above chance in both visual and auditory conditions. More important, subjects as a group selected the baited cup when only the empty cup was either shown or shaken, which means that subjects chose correctly without having seen or heard the food (i.e., inference by exclusion). Control tests showed that subjects were not more attracted to noisy cups, avoided shaken noiseless cups, or learned to use auditory information as a cue during the study. It is concluded that subjects understood that the food caused the noise, not simply that the noise was associated with the food. [ABSTRACT FROM AUTHOR]

Studies postconflict third-party affiliation in stumptailed macaques. Occurrence of multiple postconflict triadic affiliation of monkeys; Importance of analyzing the different affiliative behavior in postconflict situations; Role of third parties during postconflict period.

Studies the dynamics of reconciliation in stumptailed macaques, Macaca arctoides. Combined effects of multiple variables such as sex, age, rank and conflict, on the occurrence of reconciliation; Use of different behavior patterns in macaques' postconflict reunion; Use of postconflict allogrooming and contact sitting for the maintenance of valuable relationships.

Some cercopithecine primates direct disproportionate amounts of grooming, huddling, and agonistic support toward maternal kin. Disproportionate amounts of aggression are also directed toward maternal kin, however, suggesting that mechanisms that restore relationships damaged by aggression, such as reconciliation, might be biased toward these preferred social partners. Studies investigating kinship effects and reconciliation are inconsistent, however, perhaps because of differences in the environmental conditions under which behavior was observed. In order to test the effects of kinship and spatial density on affiliative and reconciliation behavior, we conducted focal and scan rumpling on a group of rhesus monkeys (Macaca mulatta) living in an outdoor corral under low spatial density conditions. We then compared this data to previously published dam on a group of the same species living under higher spatial density conditions. Neither overall grooming nor reconciliation were affected by spatial density once correction procedures were applied. Grooming was kin biased at both study sites, whereas reconciliation was kin biased only in the low-density group. Although data failed to support a Coping Model according to which grooming and reconciliation should go up under higher densities, we suggest that coping may he reflected not so much in overall rates of behavior hut in strategic partner choices, such as the increased importance monkeys under crowded conditions appear to attach to nonkin partners. [ABSTRACT FROM AUTHOR]

Prosociality can be defined as any behaviour performed to alleviate the needs of others or to improve their welfare. Prosociality has probably played an essential role in the evolution of cooperative behaviour and several studies have already investigated it in primates to understand the evolutionary origins of human prosociality. Two main tasks have been used to test prosociality in a food context. In the Platforms task, subjects can prosocially provide food to a partner by selecting a prosocial platform over a selfish one. In the Tokens task, subjects can prosocially provide food to a partner by selecting a prosocial token over a selfish one. As these tasks have provided mixed results, we used both tasks to test prosociality in great apes, capuchin monkeys and spider monkeys. Our results provided no compelling evidence of prosociality in a food context in any of the species tested. Additionally, our study revealed serious limitations of the Tokens task as it has been previously used. These results highlight the importance of controlling for confounding variables and of using multiple tasks to address inconsistencies present in the literature. [ABSTRACT FROM AUTHOR]

Cognition has been extensively studied in primates while other, more distantly related taxa have been neglected for a long time. More recently, there has been an increased interest in avian cognition, with the focus mostly on big-brained species like parrots and corvids. However, the majority of bird species has never systematically been studied in diverse cognitive tasks other than memory and learning tasks, so not much can yet be concluded about the relevant factors for the evolution of cognition. Here we examined 3 species of the estrildid finch family in problem-solving tasks. These granivorous, non-tool-using birds are distributed across 3 continents and are not known for high levels of innovation or spontaneous problem solving in the wild. In this study, our aim was to find such abilities in these species, assess what role domestication might play with a comparison of 4 genetically separated zebra finch strains, and to look for between-species differences between zebra finches, Bengalese finches, and diamond firetails. Furthermore, we established a 3-step spontaneous problem-solving procedure with increasing levels of complexity. Results showed that some estrildid finches were generally capable of spontaneously solving problems of variable complexity to obtain food. We found striking differences in these abilities between species, but not between strains within species, and offer a discussion of potential reasons. Our established methodology can now be applied to a larger number of bird species for phylogenetic comparisons on the behavioral level to get a deeper understanding of the evolution of cognitive abilities. [ABSTRACT FROM AUTHOR]

Social manipulation represents an important aspect of human social interactions, including cooperative ones. Yet, little is known about social manipulation of conspecifics in nonhuman great apes. We investigated how orang-utan, Pongo abelii , mothers used their offspring as a means to access food in competitive and cooperative test situations. In the competitive situations, only the offspring could retrieve high-value food rewards. Here, orang-utan mothers often stole the food from their offspring and even coerced them into retrieving it to begin with, by moving the offspring to the test site, guiding their arms and bodies towards the food, and even reorienting their hands so that they would grab the food. However, modifying the task constraints so that mothers were now required to cooperate with their offspring to obtain the food changed the mothers' behaviour completely. Suddenly, mothers cooperated with their offspring by handing them tools that only their offspring could use to activate a mechanism delivering food for both of them. We conclude that orang-utans, like humans, are able to flexibly use conspecifics as a social tool and that this kind of social tool use supports their ability to cooperate. [ABSTRACT FROM AUTHOR]

Nonhuman great apes and human children were tested for an understanding that appearance does not always correspond to reality. Subjects were 29 great apes (bonobos [Pan paniscus], chimpanzees [Pan troglodytes], gorillas [Gorilla gorilla], and orangutans [Pongo abelii]) and 24 21/2-year-old children. In our task, we occluded portions of 1 large and 1 small food stick such that the size relations seemed reversed. Subjects could then choose which one they wanted. There was 1 control condition and 2 experimental conditions (administered within subjects). In the control condition subjects saw only the apparent stick sizes, whereas in the 2 experimental conditions they saw the true stick sizes as well (the difference between them being what the subjects saw first: the apparent or the real stick sizes). All great ape species and children successfully identified the bigger stick, despite its smaller appearance, in the experimental conditions, but not in the control. We discuss these results in relation to the understanding of object permanence and conservation, and exclude reversed reward contingency learning as an explanation. [ABSTRACT FROM AUTHOR]

Innovation has been defined as a solution to a novel problem or a novel solution to an old problem. The second part of this definition requires the inhibition of previously learnt solution strategies before a novel solution can be found. Therefore, inventing novel solutions for an old problem is considered to be particularly difficult. We investigated the ability of great apes to produce multiple new solutions to a task after each of those solutions became obsolete. We presented all four nonhuman great ape species with a task consisting of extracting a food reward from a puzzle box. Initially, the task could be solved in three different ways that varied in difficulty. After subjects discovered the first solution, we allowed them to use it for some trials and then it became obsolete. If the apes could overcome their initial response and find the next solution, we again allowed them to use it for some time and once again it became obsolete. The final step consisted of finding the third solution to secure the food reward. We found that all species except orang-utans, Pongo abelii, were able to solve all versions of the problem. Furthermore, they overcame the obsolete techniques quickly and efficiently, indicating high degrees of behavioural flexibility and inhibitory control. In contrast to previous research on social learning, our results suggest that great apes are not conservative and adjust their behaviour flexibly when the physical constraints of a task change. [Copyright &y& Elsevier]

The trap-tube problem is difficult for chimpanzees to solve; in several studies only I to 2 subjects learn the solution. The authors tested eight chimpanzees on a non-tool-using version of the problem to investigate whether the inclusion of a tool in previous tests of the trap problem may have masked the ability of chimpanzees to solve it. All eight learned to avoid the trap, in 40 to 100 trials. One transferred to two tasks that had no visual cue in common. The authors examined the performance of 15 chimpanzees on a new task in a 2 x 2 design: seven had experience on the two-trap box, eight had not; half of each group was tested with a tool, half without one. An ANOVA revealed a significant effect of tool-inclusion and experience (p < .05). Our results show that including a tool in the trap problem profoundly affects the ability of chimpanzees to solve it. With regard to what the chimpanzees had learned, the results support the notion that rather than using the available stimuli as arbitrary cues, the subjects had encoded information about functional properties. [ABSTRACT FROM AUTHOR]

Dogs are especially skilful at comprehending human communicative signals. This raises the question of whether they are also able to produce such signals flexibly, specifically, whether they helpfully produce indicative (‘showing’) behaviours to inform an ignorant human. In experiment 1, dogs indicated the location of an object more frequently when it was something they wanted themselves than when it was something the human wanted. There was some suggestion that this might be different when the human was their owner. So in experiment 2 we investigated whether dogs could understand when the owner needed helpful information to find a particular object (out of two) that they needed. They did not. Our findings, therefore, do not support the hypothesis that dogs communicate with humans to inform them of things they do not know. [Copyright &y& Elsevier]

Contextual imitation of intransitive actions within a third-party copying setting was tested in 180 household dogs. A demonstrator dog, in sight of observer dogs, performed one of two trained actions upon hearing verbal commands given by an experimenter. Observer dogs were later tested to see whether they produced more target actions than control groups who had not seen demonstrations of those actions. In all conditions, except one, the demonstrated actions had been previously trained in the observer dogs by their owners, but had been attached to a different verbal command to that used in our study. For these ‘pretrained’ actions we further investigated whether reward contingency, the relationship of the dog to the human experimenter and ostensive cues had an effect. In no condition did we find any contextual imitation. A subsample of all tested dogs had, during their lifetimes, received extensive training in a diverse range of tasks outside of social learning, but this background similarly did not lead to contextual imitation. We conclude that dogs, even when highly trained, fail to show evidence of contextual imitation for intransitive actions within a third-party copying paradigm. [Copyright &y& Elsevier]

Although dogs, Canis familiaris, are skilful at responding to human social cues, the role of ontogeny in the development of these abilities has not been systematically examined. We studied the ability of very young dog puppies to follow human communicative cues and successfully find hidden food. In the first experiment we compared 6-, 8-, 16- and 24-week-old puppies in their ability to use pointing gestures or a marker as a cue. The results showed that puppies, independent of age, could use all human communicative cues provided; only their success at using the marker cue increased with age. In the second and third experiments we investigated the flexibility of the puppies'' understanding by reducing the degree to which they could use local enhancement to solve these problems. Here, subjects could not simply approach the hand of the experimenter and follow its direction to the correct location because cups were placed next to the dog instead of next to the experimenter. Six-week-old puppies readily used all of the human communicative cues provided. These findings support the hypothesis that domestication played a critical role in shaping the ability of dogs to follow human-given cues. [Copyright &y& Elsevier]