Nicolas Baumard (2018), Psychological Origins of the Industrial RevolutionBehavioral and Brain Sciences . Behavioral and Brain Sciences, 1-47.

Résumé :
Since the Industrial Revolution, human societies have experienced high and sustained rates of economic growth. Recent explanations of this sudden and massive change in economic history have held that modern growth results from an acceleration of innovation. But it is unclear why the rate of innovation drastically accelerated in England in the 18th century. An important factor might be the alteration of individual preferences with regard to innovation due to the unprecedented living standards of the English during that period, for two reasons. First, recent developments in economic history challenge the standard Malthusian view according to which living standards were stagnant until the Industrial Revolution. Pre-industrial England enjoyed a level of affluence that was unprecedented in history. Second, Life History Theory, a branch of evolutionary biology, has demonstrated that the human brain is designed to respond adaptively to variations in resourcesin the local environment. In particular, a more favorable environment (high resources, low mortality) triggers the expression of future-oriented preferences. In this paper, I argue that some of these psychological traits – a lower level of time discounting, a higher level of optimism, decreased materialistic orientation, and a higher level of trust in others – are likely to increase the rate of innovation. I review the evidence regarding the impact of affluence on preferences in contemporary as well as past populations, and conclude that the impact of affluence on neuro-cognitive systems may partly explain the modern acceleration of technological innovations and the associated economic growth.

Corre C, Noorman S, Jiang J, Palminteri S, Cohen MX, Lebreton M, van Gaal S. (2018) How the level of reward awareness changes the computational and electrophysiological signatures of reinforcement learning. The Journal of Neuroscience, 0457-18.

Résumé :
The extent to which subjective awareness influences reward processing, and thereby affects future decisions is currently largely unknown. In the present report, we investigated this question in a reinforcement-learning framework, combining perceptual masking, computational modeling and electroencephalographic recordings (human male and female participants). Our results indicate that degrading the visibility of the reward decreased -without completely obliterating- the ability of participants to learn from outcomes, but concurrently increased their tendency to repeat previous choices. We dissociated electrophysiological signatures evoked by the reward-based learning processes from those elicited by the reward-independent repetition of previous choices and showed that these neural activities were significantly modulated by reward visibility. Overall, this report sheds new light on the neural computations underlying reward-based learning and decision-making and highlights that awareness is beneficial for the trial-by-trial adjustment of decision-making strategies.

Giavazzi M, Daland R, Palminteri S, Peperkamp S, Brugières P, Jacquemot C, Schramm C, Cleret de Langavant, Bachoud-Lévi A-C.(2018) The role of the striatum in linguistic selection: Evidence from Huntington's disease and computational modeling. Cortex, 109, 189-204

Résumé :
Though accumulating evidence indicates that the striatum is recruited during language processing, the specific function of this subcortical structure in language remains to be elucidated. To answer this question, we used Huntington's disease as a model of striatal lesion. We investigated the morphological deficit of 30 early Huntington's disease patients with a novel linguistic task that can be modeled within an explicit theory of linguistic computation. Behavioral results reflected an impairment in HD patients on the linguistic task. Computational model-based analysis compared the behavioral data to simulated data from two distinct lesion models, a selection deficit model and a grammatical deficit model. This analysis revealed that the impairment derives from an increased randomness in the process of selecting between grammatical alternatives, rather than from a disruption of grammatical knowledge per se. Voxel-based morphometry permitted to correlate this impairment to dorsal striatal degeneration. We thus show that the striatum holds a role in the selection of linguistic alternatives, just as in the selection of motor and cognitive programs.

Lefebvre G, Nioche A, Bourgeois-Gironde S, Palminteri S. (2018) Contrasting temporal difference and opportunity cost reinforcement learning in an empirical money-emergence paradigm. PNAS. 115 (49) E11446-E11454

Résumé :
Money is a fundamental and ubiquitous institution in modern economies. However, the question of its emergence remains a central one for economists. The monetary search-theoretic approach studies the conditions under which commodity money emerges as a solution to override frictions inherent to interindividual exchanges in a decentralized economy. Although among these conditions, agents’ rationality is classically essential and a prerequisite to any theoretical monetary equilibrium, human subjects often fail to adopt optimal strategies in tasks implementing a search-theoretic paradigm when these strategies are speculative, i.e., involve the use of a costly medium of exchange to increase the probability of subsequent and successful trades. In the present work, we hypothesize that implementing such speculative behaviors relies on reinforcement learning instead of lifetime utility calculations, as supposed by classical economic theory. To test this hypothesis, we operationalized the Kiyotaki and Wright paradigm of money emergence in a multistep exchange task and fitted behavioral data regarding human subjects performing this task with two reinforcement learning models. Each of them implements a distinct cognitive hypothesis regarding the weight of future or counterfactual rewards in current decisions. We found that both models outperformed theoretical predictions about subjects’ behaviors regarding the implementation of speculative strategies and that the latter relies on the degree of the opportunity costs consideration in the learning process. Speculating about the marketability advantage of money thus seems to depend on mental simulations of counterfactual events that agents are performing in exchange situations.

Communiqué de presse

Mell, H., Safra, L., Algan, Y., Baumard, N., & Chevallier, C. (2018). Childhood environmental harshness predicts coordinated health and reproductive strategies: A cross-sectional study of a nationally representative sample from France. Evolution and Human Behavior, 39(1), 1-8.

Résumé :
There is considerable variation in health and reproductive behaviours within and across human populations. Drawing on principles from Life History Theory, psychosocial acceleration theory predicts that individuals developing in harsh environments decrease their level of somatic investment and accelerate their reproductive schedule. Although there is consistent empirical support for this general prediction, most studies have focused on a few isolated life history traits and few have investigated the way in which individuals apply life strategies across reproductive and somatic domains to produce coordinated behavioural responses to their environment. In our study, we thus investigate the impact of childhood environmental harshness on both reproductive strategies and somatic investment by applying structural equation modeling (SEM) to cross-sectional survey data obtained in a representative sample of the French population (n = 1015, age: 19–87 years old, both genders). This data allowed us to demonstrate that (i) inter-individual variation in somatic investment (e.g. effort in looking after health) and reproductive timing (e.g. age at first birth) can be captured by a latent fast-slow continuum, and (ii) faster strategies along this continuum are predicted by higher childhood harshness. Overall, our results s upport the existence of a fast-slow continuum and highlight the relevance of the life history approach for understanding variations in reproductive and health related behaviours.

Palminteri S, Chevallier C. (2018) Can we infer inter-individual differences in risk-taking from behavioural tasks? Frontiers in Psychology, 9, 2307

Résumé :
Investigating the bases of inter-individual differences in risk-taking is necessary to refine our cognitive and neural models of decision-making and to ultimately counter risky behaviors in real-life policy settings. However, recent evidence suggests that behavioral tasks fare poorly compared to standard questionnaires to measure individual differences in risk-taking. Crucially, using model-based measures of risk taking does not seem to improve reliability. Here, we put forward two possible – not mutually exclusive – explanations for these results and suggest future avenues of research to improve the assessment of inter-individual differences in risk-taking by combining repeated online testing and mechanistic computational models.

Safra, L., Ioannou, C., Amsellem, F., Delorme, R., & Chevallier, C. (2018). Distinct effects of social motivation on face evaluations in adolescents with and without autism. Scientific reports, 8(1), 10648

Résumé :
Individual differences in social motivation have an influence on many behaviours in both clinical and non-clinical populations. As such, social motivation has been identified as a biological trait that is particularly well-suited for dimensional approaches cutting across neuropsychological conditions. In the present paper, we tested whether social motivation had a similar impact in the general population and in a neuropsychological condition characterized by diminished social motivation: Autism Spectrum Disorders (ASD). More precisely, we evaluated the effect of social motivation on face evaluations in 20 adolescents with ASD and 20 matched controls using avatars parametrically varying in dominance and trustworthiness. In line with previous research, we found in the control group that participants with higher levels of social motivation relied more on perceived trustworthiness when producing likeability judgments. However, this pattern was not found in the ASD group. Social motivation thus appears to have a different effect in ASD and control populations, which raises questions about the relevance of subclinical or non-clinical populations to understand ASD.

Philippe Schlenker (2018). Visible Meaning: Sign language and the foundations of semantics, De Gruyter, 44, 3-4, 123-208.

Résumé :
While it is now accepted that sign languages should inform and constrain theories of ‘Universal Grammar’, their role in ‘Universal Semantics’ has been under-studied. We argue that they have a crucial role to play in the foundations of semantics, for two reasons. First, in some cases sign languages provide overt evidence on crucial aspects of the Logical Form of sentences, ones that are only inferred indirectly in spoken language. For instance, sign language ‘loci’ are positions in signing space that can arguably realize logical variables, and the fact that they are overt makes it possible to revisit foundational debates about the syntactic reality of variables, about mechanisms of temporal and modal anaphora, and about the existence of dynamic binding. Another example pertains to mechanisms of ‘context shift’, which were postulated on the basis of indirect evidence in spoken language, but which are arguably overt in sign language. Second, along one dimension sign languages are strictly more expressive than spoken languages because iconic phenomena can be found at their logical core. This applies to loci themselves, which may simultaneously function as logical variables and as schematic pictures of what they denote (context shift comes with some iconic requirements as well). As a result, the semantic system of spoken languages can in some respects be seen as a simplified version of the richer semantics found in sign languages. Two conclusions could be drawn from this observation. One is that the full extent of Universal Semantics can only be studied in sign languages. An alternative possibility is that spoken languages have comparable expressive mechanisms, but only when co-speech gestures are taken into account (as recently argued by Goldin-Meadow and Brentari). Either way, sign languages have a crucial role to play in investigations of the foundations of semantics.

Communiqué de presse

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