A Colour Sorting Task Reveals the Limits of the Universalist/Relativist Dichotomy: Colour Categories Can Be Both Language Specific and Perceptual

We designed a new protocol requiring French adult participants to group a large number of Munsell colour chips into three or four groups. On one, relativist, view, participants would be expected to rely on their colour lexicon in such a task. In this framework, the resulting groups should be more similar to French colour categories than to other languages categories. On another, universalist, view, participants would be expected to rely on universal features of perception. In this second framework, the resulting groups should match colour categories of three and four basic terms languages. In this work, we first collected data to build an accurate map of French colour terms categories. We went on testing how native French speakers spontaneously sorted a set of randomly presented coloured chips and, in line with the relativist prediction, we found that the resulting colour groups were more similar to French colour categories than to three and four basic terms languages. However, the same results were obtained in a verbal interference condition, suggesting that participants rely on language specific and nevertheless perceptual, colour categories. Collectively, these results suggest that the universalist/relativist dichotomy is a too narrow one

Probability matching is not the default decision making strategy in human and non-human primates

Probability matching has long been taken as a prime example of irrational behaviour in human decision making; however, its nature and uniqueness in the animal world is still much debated. In this paper we report a set of four preregistered experiments testing adult humans and Guinea baboons on matched probability learning tasks, manipulating task complexity (binary or ternary prediction tasks) and reinforcement procedures (with and without corrective feedback). Our findings suggest that probability matching behaviour within primate species is restricted to humans and the simplest possible binary prediction tasks; utility-maximising is seen in more complex tasks for humans as pattern-search becomes more effortful, and we observe it across the board in baboons, altogether suggesting that it is a cognitively less demanding strategy. These results provide further evidence that neither human nor non-human primates default to probability matching; however, unlike other primates, adult humans probability match when the cost of pattern search is low

Action-matching biases in monkeys (Sapajus spp.) in a stimulus-response compatibility task: Evaluating experience-dependent malleability

Stimulus-response compatibility effects occur when observing certain stimuli facilitate the performance of a related response and interfere with performing an incompatible or different response. Using stimulus-response action pairings, this phenomenon has been used to study imitation effects in humans, and here we use a similar procedure to examine imitative biases in non-human primates. Eight capuchin monkeys (Sapajus spp.) were trained to perform hand and mouth actions in a stimulus-response compatibility task. Monkeys rewarded for performing a compatible action (i.e., using their hand or mouth to perform an action after observing an experimenter use the same effector) performed significantly better than those rewarded for incompatible actions (i.e., performing an action after observing an experimenter use the other effector), suggesting an initial bias for imitative action over an incompatible S-R pairing. After a predetermined number of trials, reward contingencies were reversed; i.e., monkeys initially rewarded for compatible responses were now rewarded for incompatible responses, and vice versa. In this second training stage no difference in performance was identified between monkeys rewarded for compatible or incompatible actions, suggesting any imitative biases were now absent. In a second experiment, two monkeys learned both compatible and incompatible reward contingencies in a series of learning reversals. Overall, no difference in performance ability could be attributed to the type of rule (compatible/incompatible) being rewarded. Together, these results suggest that monkeys exhibit a weak bias towards action copying, which (in line with findings from humans) can largely be eliminated through counter-imitative experience

Rational After All: Changes in Probability Matching Behaviour Across Time in Humans and Monkeys

Probability matching—where subjects given probabilistic in-put respond in a way that is proportional to those input probabilities—has long been thought to be characteristic of primate performance in probability learning tasks in a variety of contexts, from decision making to the learning of linguistic variation in humans. However, such behaviour is puzzling because it is not optimal in a decision theoretic sense; the optimal strategy is to always select the alternative with the highest positive-outcome probability, known as maximising(in decision making) or regularising (in linguistic tasks). While the tendency to probability match seems to depend somewhat on the participants and the task (i.e., infants are less likely to probability match than adults, monkeys probability matchless than humans, and probability matching is less likely in linguistic tasks), existing studies suffer from a range of deficiencies which make it difficult to robustly assess these differences. In this project we present a series of experiments which systematically test the development of probability matching behaviour over time in simple decision making tasks, across species (humans and Guinea baboons), task complexity, and task domain (linguistic vs non-linguistic)

From temporal network data to the dynamics of social relationships

Networks are well-established representations of social systems, and temporal networks are widely used to study their dynamics. Temporal network data often consist in a succession of static networks over consecutive time windows whose length, however, is arbitrary, not necessarily corresponding to any intrinsic timescale of the system. Moreover, the resulting view of social network evolution is unsatisfactory: short time windows contain little information, whereas aggregating over large time windows blurs the dynamics. Going from a temporal network to a meaningful evolving representation of a social network therefore remains a challenge. Here we introduce a framework to that purpose: transforming temporal network data into an evolving weighted network where the weights of the links between individuals are updated at every interaction. Most importantly, this transformation takes into account the interdependence of social relationships due to the finite attention capacities of individuals: each interaction between two individuals not only reinforces their mutual relationship but also weakens their relationships with others. We study a concrete example of such a transformation and apply it to several data sets of social interactions. Using temporal contact data collected in schools, we show how our framework highlights specificities in their structure and temporal organization. We then introduce a synthetic perturbation into a data set of interactions in a group of baboons to show that it is possible to detect a perturbation in a social group on a wide range of timescales and parameters. Our framework brings new perspectives to the analysis of temporal social networks

Cumulative cultural evolution in a non-copying task in children and Guinea baboons

International audienceThe unique cumulative nature of human culture has often been explained by high-fidelity copying mechanisms found only in human social learning. However, transmission chain experiments in human and non-human primates suggest that cumulative cultural evolution (CCE) might not be dependent on high-fidelity copying after all. In this study we test whether CCE is possible even with a non-copying task. We performed transmission chain experiments in Guinea baboons and children where individuals observed and reproduced visual patterns on touch screen devices. In order to be rewarded, participants had to avoid touching squares that were touched by a previous participant. In other words, they were regarded for innovation rather than copying. Results nevertheless exhibited two fundamental properties of CCE: an increase over generations in task performance and the emergence of systematic structure. However, CCE arose from different mechanisms across species: children, unlike baboons, converged in behaviour over generations by copying specific patterns in a different location, thus introducing alternative copying mechanisms into the non-copying task. We conclude that CCE can result from non-copying tasks and that there is a broad spectrum of possible mechanisms that will lead to CCE aside from high-fidelity transmission

Selective and Contagious Prosocial Resource Donation in Capuchin Monkeys, Chimpanzees and Humans

Prosocial acts benefitting others are widespread amongst humans. By contrast, chimpanzees have failed to demonstrate such a disposition in several studies, leading some authors to conclude that the forms of prosociality studied evolved in humans since our common ancestry. However, similar prosocial behavior has since been documented in other primates, such as capuchin monkeys. Here, applying the same methodology to humans, chimpanzees, and capuchins, we provide evidence that all three species will display prosocial behavior, but only in certain conditions. Fundamental forms of prosociality were age-dependent in children, conditional on self-beneficial resource distributions even at age seven, and conditional on social or resource configurations in chimpanzees and capuchins. We provide the first evidence that experience of conspecific companions’ prosocial behavior facilitates prosocial behavior in children and chimpanzees. Prosocial actions were manifested in all three species following rules of contingency that may reflect strategically adaptive responses

Théories darwiniennes de l'évolution culturelle : modèles et mécanismes

The purpose of this thesis is to conduct a critical review of key Darwinian models of cultural evolution, to show to what extent and how cultural change is analogous to biological evolution and to propose conceptual and formal models to study cultural evolution in this perspective. Three separate theories are studied. Memetic is based on the idea that a psychological mechanism analogous to the replication in biology exists in the cultural domain. We show that imitation is not faithful enough to play this role and therefore that the memetic model cannot serve as a basis for a general theory of cultural phenomena. The theory of gene culture co-evolution is based on the idea that selection is a dominant factor of evolution and argues that there are several psychological mechanisms and forces specific to the cultural field. However, we show that the importance of selection depends on other forces and is not necessarily dominant. Finally, in a chapter devoted to the study of cultural epidemiology, we defend the idea that the psychological mechanisms tend to be modular and to maximize relevance. These two properties are responsible for the fact that psychological mechanisms construct the cultural elements they transmit. Attraction is the result of these transformations at the population level and can explain the stability and evolution of cultural elements. Attraction and selection are the two sources of stability of cultural elements. Cultural evolution is therefore Darwinian in a populational sense.L'objet de cette thèse est de réaliser une revue critique des principaux modèles Darwiniens de l'évolution culturelle, de montrer dans quelle mesure et de quelle façon l'évolution culturelle est analogue à l'évolution biologique et de proposer des instruments conceptuels et formels pour étudier l'évolution culturelle dans cette perspective. Trois ensembles théoriques distincts sont étudiés. La mémétique repose sur l'idée qu'il existe dans le domaine culturel un mécanisme psychologique équivalent à la réplication en biologie. Nous montrons que l'imitation n'est pas assez fidèle pour jouer pleinement ce rôle et donc que le modèle mémétique ne peut pas servir de base à une théorie générale des phénomènes culturels. La théorie de la coévolution gène-culture part de l'idée que la sélection est un facteur dominant de l'évolution et soutient qu'il existe plusieurs mécanismes psychologiques et forces propres au domaine culturel. Nous montrons que l'importance de la sélection est à relativiser et dépend d'autres forces. Dans une partie dédiée à l'étude de l'épidémiologie culturelle, nous défendons l'idée selon laquelle les mécanismes psychologiques tendent à être modulaires et à maximiser la pertinence. Ces deux propriétés font que les mécanismes psychologiques construisent les éléments culturels qu'ils transmettent. Le phénomène d'attraction, conséquence à l'échelle de la population de ces transformations successives, permet d'expliquer la stabilité et l'évolution des éléments culturels. Attraction et sélection sont les deux sources de la stabilité des éléments culturels. L'évolution culturelle est donc à penser dans un cadre Darwinien populationnel