Chimpanzee coordination and potential communication in a two-touchscreen turn-taking game

Recent years have seen a growing interest in the question of whether and how groups of nonhuman primates coordinate their behaviors for mutual benefit. On the one hand, it has been shown that chimpanzees in the wild and in captivity can solve various coordination problems. On the other hand, evidence of communication in the context of coordination problems is scarce. Here, we investigated how pairs of chimpanzees (Pan troglodytes) solved a problem of dynamically coordinating their actions for achieving a joint goal. We presented five pairs of chimpanzees with a turn-taking coordination game, where the task was to send a virtual target from one computer display to another using two touch-screens. During the joint practice of the game some subjects exhibited spontaneous gesturing. To address the question whether these gestures were produced to sustain coordination, we introduced a joint test condition in which we simulated a coordination break-down scenario: subjects appeared either unwilling or unable to return the target to their partner. The frequency of gesturing was significantly higher in these test trials than in the regular trials. Our results suggest that at least in some contexts chimpanzees can exhibit communicative behaviors to sustain coordination in joint action

A comparative perspective on three primate species’ responses to a pictorial emotional Stroop task

This study was also supported (in part) by a grant from The David Bohnett Foundation, the Leo S. Guthman Fund, the Chauncey and Marion Deering McCormick Foundation, and, at the time of writing, L.M.H. was supported by the Women’s Board of Lincoln Park Zoo.The Stroop effect describes interference in cognitive processing due to competing cognitive demands. Presenting emotionally laden stimuli creates similar Stroop-like effects that result from participants’ attention being drawn to distractor stimuli. Here, we adapted the methods of a pictorial Stroop study for use with chimpanzees (N = 6), gorillas (N = 7), and Japanese macaques (N = 6). We tested all subjects via touchscreens following the same protocol. Ten of the 19 subjects passed pre-test training. Subjects who reached criterion were then tested on a standard color-interference Stroop test, which revealed differential accuracy in the primates’ responses across conditions. Next, to test for an emotional Stroop effect, we presented subjects with photographs that were either positively valenced (a preferred food) or negatively valenced (snakes). In the emotional Stroop task, as predicted, the primates were less accurate in trials which presented emotionally laden stimuli as compared to control trials, but there were differences in the apes’ and monkeys’ response patterns. Furthermore, for both Stroop tests, while we found that subjects’ accuracy rates were reduced by test stimuli, in contrast to previous research, we found no difference across trial types in the subjects’ response latencies across conditions.Publisher PDFPeer reviewe

Chimpanzees (Pan troglodytes) navigate to find hidden fruit in a virtual environment

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The evolution of primate short-term memory

– Short-term memory is implicated in a range of cognitive abilities and is critical for understanding primate cognitive evolution. To investigate the effects of phylogeny, ecology and sociality on short-term memory, we tested the largest and most diverse primate sample to date (421 non-human primates across 41 species) in an experimental delayed-response task. Our results confirm previous findings that longer delays decrease memory performance across species and taxa. Our analyses demonstrate a considerable contribution of phylogeny over ecological and social factors on the distribution of short-term memory performance in primates; closely related species had more similar short-term memory abilities. Overall, individuals in the branch of Hominoidea performed better compared to Cercopithecoidea, who in turn performed above Platyrrhini and Strepsirrhini. Interdependencies between phylogeny and socioecology of a given species presented an obstacle to disentangling the effects of each of these factors on the evolution of shortterm memory capacity. However, this study offers an important step forward in understanding the interspecies and individual variation in short-term memory ability by providing the first phylogenetic reconstruction of this trait’s evolutionary history. The dataset constitutes a unique resource for studying the evolution of primate cognition and the role of short-term memory in other cognitive abilities

Food cleaning in gorillas: Social learning is a possibility but not a necessity

Food cleaning is widespread in the animal kingdom, and a recent report confirmed that (amongst other behaviours) wild western lowland gorillas also show food cleaning. The authors of this report conclude that this behaviour, based on its distribution patterns, constitutes a potential candidate for culture. While different conceptualisations of culture exist, some more and some less reliant on behavioural form copying, all of them assign a special role to social learning processes in explaining potentially cultural behaviours. Here we report the results of an experiment that tested to what extent food cleaning behaviour in a group of captive Western lowland gorillas (Gorilla gorilla gorilla) relies on social learning processes. Subjects were provided with clean and dirty apples. When they were provided with dirty apples, all subjects showed evidence of food cleaning in at least 75% of trials. Preferred cleaning techniques differed between individuals, four out of five of subjects expressed a behaviour analogous to that reported in wild conspecifics. Given this occurrence of food cleaning in a culturally unconnected population of gorillas, we conclude that social learning is unlikely to play a central role in the emergence of the food cleaning behavioural form in Western lowland gorillas; instead, placing a greater emphasis on individual learning of food cleaning’s behavioural form

The Evolution of Primate Short-Term Memory.

Short-term memory is implicated in a range of cognitive abilities and is critical for understanding primate cognitive evolution. To investigate the effects of phylogeny, ecology and sociality on short-term memory, we tested the largest and most diverse primate sample to date (421 non-human primates across 41 species) in an experimental delayed-response task. Our results confirm previous findings that longer delays decrease memory performance across species and taxa. Our analyses demonstrate a considerable contribution of phylogeny over ecological and social factors on the distribution of short-term memory performance in primates; closely related species had more similar short-term memory abilities. Overall, individuals in the branch of Hominoidea performed better compared to Cercopithecoidea, who in turn performed above Platyrrhini and Strepsirrhini. Interdependencies between phylogeny and socioecology of a given species presented an obstacle to disentangling the effects of each of these factors on the evolution of short-term memory capacity. However, this study offers an important step forward in understanding the interspecies and individual variation in short-term memory ability by providing the first phylogenetic reconstruction of this trait’s evolutionary history. The dataset constitutes a unique resource for studying the evolution of primate cognition and the role of short-term memory in other cognitive abilities.info:eu-repo/semantics/publishedVersio

Object manipulation and tool use in Nicobar long-tailed macaques (Macaca fascicularis umbrosus)

This is an accepted manuscript of an article published by Springer in International Journal of Primatology on 08/09/2020, available online: https://link.springer.com/article/10.1007%2Fs10764-020-00141-y The accepted version of the publication may differ from the final published version.Object manipulation and tool use by non-human primates have received considerable attention from primatologists and anthropologists, because of their broad implications for understanding the evolution of tool use in humans. To date, however, most of the studies on this topic have focused on apes, given their close evolutionary relationship with humans. In contrast, fewer studies on tool use and object manipulation have been conducted on monkeys. Documenting and studying object manipulation and tool use in species that are more distantly related to humans can provide a broader perspective on the evolutionary origins of this behaviour. We present a detailed description of toolaided behaviours and object manipulation by Nicobar long-tailed macaques ( Macaca fascicularis umbrosus ) living along the coastlines of Great Nicobar Island. We made observations from December 2018 to March 2019, using ad libitum and focal sampling methods. We observed behaviours related to object manipulation and tool use in six different behavioural contexts (foraging, hygiene, communication, play, selfdirected and self-hygiene behaviour) involving eight different types of objects, namely resonance rod, play object, rolling platform, scraping tool, dental groom, pounding substrate, leaves as grip pads and wipers, and stimulation tool. We observed that males were involved in tool use and object manipulation more frequently than females. Our results add to existing records of object manipulation, tool-use behaviour and tool variants displayed by non-human primates, showing that Nicobar macaques perform multiple and diverse tool-aided behaviours

The evolution of primate short-term memory

Short-term memory is implicated in a range of cognitive abilities and is critical for understanding primate cognitive evolution. To investigate the effects of phylogeny, ecology and sociality on short-term memory, we tested the largest and most diverse primate sample to date (421 non-human primates across 41 species) in an experimental delayed-response task. Our results confirm previous findings that longer delays decrease memory performance across species and taxa. Our analyses demonstrate a considerable contribution of phylogeny over ecological and social factors on the distribution of short-term memory performance in primates; closely related species had more similar short-term memory abilities. Overall, individuals in the branch of Hominoidea performed better compared to Cercopithecoidea, who in turn performed above Platyrrhini and Strepsirrhini. Interdependencies between phylogeny and socioecology of a given species presented an obstacle to disentangling the effects of each of these factors on the evolution of shortterm memory capacity. However, this study offers an important step forward in understanding the interspecies and individual variation in short-term memory ability by providing the first phylogenetic reconstruction of this trait’s evolutionary history. The dataset constitutes a unique resource for studying the evolution of primate cognition and the role of short-term memory in other cognitive abilities

A comparative perspective on three primate species’ responses to a pictorial emotional Stroop task

The Stroop effect describes interference in cognitive processing due to competing cognitive demands. Presenting emotionally laden stimuli creates similar Stroop-like effects that result from participants’ attention being drawn to distractor stimuli. Here, we adapted the methods of a pictorial Stroop study for use with chimpanzees (N = 6), gorillas (N = 7), and Japanese macaques (N = 6). We tested all subjects via touchscreens following the same protocol. Ten of the 19 subjects passed pre-test training. Subjects who reached criterion were then tested on a standard color-interference Stroop test, which revealed differential accuracy in the primates’ responses across conditions. Next, to test for an emotional Stroop effect, we presented subjects with photographs that were either positively valenced (a preferred food) or negatively valenced (snakes). In the emotional Stroop task, as predicted, the primates were less accurate in trials which presented emotionally laden stimuli as compared to control trials, but there were differences in the apes’ and monkeys’ response patterns. Furthermore, for both Stroop tests, while we found that subjects’ accuracy rates were reduced by test stimuli, in contrast to previous research, we found no difference across trial types in the subjects’ response latencies across conditions