Biology subjects

Rakoczy, H.

Publications and source records attributed to Rakoczy, H..

5 recordsLinked to original sources

bioRxiv2025

Social evaluation of skilfulness in Tonkean macaques (Macaca tonkeana) and brown capuchins (Sapajus apella)

For optimal decision-making, social animals can benefit from evaluating others behaviours. Some species seemingly consider the skills of others when deciding who to interact with in different contexts. Yet, whether and how nonhuman animals form impressions about others competence is still unclear. In this study, we investigated whether Tonkean macaques (Macaca tonkeana) and brown capuchins (Sapajus apella) can evaluate the skilfulness of others. Subjects observed two human actors (one skilful, one unskilled) trying to open several food containers. Only the skilful actor successfully opened the containers and released food so the experimenter could give it to the subjects. Afterwards, subjects did not choose the skilful actor significantly more frequently than the unskilled one. Their choices for the skilful actor did not increase through trials, nor were they based on the outcomes experienced in previous trials. However, when we considered their initial preferences for the human actors, we observed a significant shift in preference for the skilful actor. Our subjects also looked preferentially at the skilful over the unskilled actor when both simultaneously manipulated a container. We observed substantial individual variation and species differences in choice and looking behaviours. While the cognitive mechanisms (impression formation vs outcome-based process) underlying these social decisions are still unclear, our findings indicate that Tonkean macaques and brown capuchins used social information about the actors skills to inform their decisions.

animal behavior and cognition↗

bioRxiv2025

Tonkean macaques do not prefer the helper or the hinderer in the hill paradigm

Evaluating others prosocial tendencies can benefit individuals by allowing them to interact with prosocial individuals and avoid antisocial ones. The ontogeny of humans strong prosocial preference has been widely investigated using the hill paradigm. Childrens preference for helper over hinderer agents was measured after they watched a scene in which the helper agent pushed a climber up a hill while the hinderer agent pushed the climber down the hill. Bonobos tested with the hill paradigm preferred the hinderer over the helper, contrasting previous findings for other nonhuman primates. We tested Tonkean macaques (Macaca tonkeana) using the same procedure as the one used with bonobos to see whether they would also exhibit a hinderer preference. Subjects did not prefer the helper over the hinderer (or vice versa). The low attentional level observed in our subjects suggests a lack of interest in the video stimuli. This finding relates to more general questions regarding how animals perceive abstract animated onscreen stimuli and the relevance of the hill paradigm in investigating prosocial preferences. Studies using various experimental paradigms with conspecifics or human actors as social agents are needed to investigate further the social evaluation of prosocial behaviours in Tonkean macaques, bonobos, and other primates.

animal behavior and cognition↗

bioRxiv2024

Choose your partner: Social evaluation of skilfulness at cooperative co-action tasks in Tonkean macaques (Macaca tonkeana)

Social evaluation - inferring individual characteristics of others from their past behaviours - is an adaptive strategy that helps to inform social decisions. However, how nonhuman primates form and use impressions about others to select their social partners strategically is still unclear. In this study, we investigated whether Tonkean macaques, Macaca tonkeana, can spontaneously use information, acquired by observation, to choose the optimal partners for cooperation in two co-action tasks from the same domain. The subjects (N=5) did not prefer to cooperate with the skilful partner compared to the unskilled partner, irrespective of the task or how much attention they paid to the partners actions solving a solo version of one task prior to the test. The probability of optimal choices did not increase through trials either, indicating no learning by experience with the partners across the 16 test trials. Our results contradict findings of previous studies that tested monkeys in different domains of competence and contexts, and thus encourage further investigation on monkeys social evaluation abilities. Our experimental design presents a promising way to investigate different contexts, the inter-individual differences, the different types of social information involved, and the cognitive mechanisms underlying social evaluation and partner selectivity in nonhuman primates.

animal behavior and cognition↗

bioRxiv2019

Long-tailed macaques extract statistical information from repeated types of events to make rational decisions under uncertainty

Human children and apes are proficient intuitive statisticians when making predictions from populations of objects to randomly drawn samples, whereas monkeys seem not to be. Statistical reasoning can also be investigated in tasks in which the probabilities of different possibilities must be inferred from relative frequencies of events, but little is known about the performance of nonhuman primates in such tasks. In the current study, we investigated whether long-tailed macaques extract statistical information from repeated types of events to make predictions under uncertainty. In each experiment, monkeys first experienced the probability of rewards associated with different factors separately. In a subsequent test trial, monkeys could then choose between the different factors presented simultaneously. In Experiment 1, we tested whether long-tailed macaques relied on probabilities and not on a comparison of absolute quantities to make predictions. In Experiment 2 and 3 we varied the nature of the predictive factors and the complexity of the covariation structure between rewards and factors. Results indicate that long-tailed macaques extract statistical information from repeated types of events to make predictions and rational decisions under uncertainty, in more or less complex scenarios. These findings suggest that, given the right input information, monkeys are intuitive statisticians.

animal behavior and cognition↗

bioRxiv2018

Do long-tailed macaques engage in intuitive statistics?

Human infants, apes and capuchins have been found to engage in intuitive statistics, generating predictions from populations to samples based on proportional information. This suggests that statistical reasoning might depend on some core knowledge that is shared with other species. Here, we investigated whether such intuitive statistical reasoning is also present in a species of Old World monkeys, to aid in the reconstruction of the evolution of this capacity. In a series of 7 test conditions, 11 long-tailed macaques were offered different pairs of populations containing varying proportions of preferred vs. neutral food items. One population always contained a higher proportion of preferred items than the other. An experimenter simultaneously drew one item out of each population, hid them in her fists and presented them to the monkey to choose. Results revealed that at least one individual seemed to make systematic population-to-sample inferences and consistently chose the sample from the population with the more favorable distribution of preferred vs. neutral food items. While it is not clear whether she used relative or absolute quantities of food, she seemed to understand the difference between a correct choice and a favorable draw and thus some basic principles of intuitive statistics.

animal behavior and cognition↗