Shortcomings of experimental economics to study human behavior: a reanalysis of Cohn et al. 2014, Nature 516, 86–89, ‘‘Business culture and dishonesty in the banking industry’’

In the wake of financial scandals, Cohn and collaborators published a headline-grabber study in the field of behavioral economics. M.C. Villeval (2014) summarized the main message as follows, in News and Views of the Nature issue where the Cohn study was published: the “experiment shows that although bank employees behave honestly on average, their dishonesty increases when they make decisions after having been primed to think about their professional identity.” Cohn et al. thus provide evidence that “the incentives and the business culture developed in the financial sector may undermine the honesty norms of ordinary employees.” This study may have important consequences for policy, since, Villeval continues, “it is crucial to ensure a business culture of honesty in this industry to restore trust in it.” Villeval also argues that “from a scientific perspective, this study […] supports the economic theory of social identity […], links this theory with the economic analysis of lying behavior [… and] shows how behavioural economists can contribute to a broader reflection in science about how people manage their 'multiple selves' ”. Here I show that the use of flawed statistics methods, yet employed routinely in so-called “evidence-based” science, led the authors to distort the “evidence”. I am also using this data-set as an interesting example to explore how we can use modeling and simulations to provide a fair account of the information and uncertainty conveyed by the data, based on Confidence Intervals. I provide the R-code. Based on this paper, I question the contribution of behavioral economics to the understanding of human behavior and conclude with considerations on honesty and science

A critical review of the neuroimaging literature on synesthesia

International audienceSynesthesia refers to additional sensations experienced by some people for specific stimulations, such as the systematic arbitrary association of colors to letters for the most studied type. Here, we review all the studies (based mostly on functional and structural magnetic resonance imaging) that have searched for the neural correlates of this subjective experience, as well as structural differences related to synesthesia. Most differences claimed for synesthetes are unsupported, due mainly to low statistical power, statistical errors, and methodological limitations. Our critical review therefore casts some doubts on whether any neural correlate of the synesthetic experience has been established yet. Rather than being a neurological condition (i.e., a structural or functional brain anomaly), synesthesia could be reconsidered as a special kind of childhood memory, whose signature in the brain may be out of reach with present brain imaging techniques

Nature humaine - L'être humain est-il écocidaire par nature ?

International audienc

Histoire et environnement

International audienceLa proposition est d'aborder ce sujet, non pas classiquement autour d'un champ disciplinaire (l'histoire environnementale, sa genèse, ses courants, ses méthodes...) mais en partant de l'expérience personnelle de chercheurs, de leurs interrogations et de leurs engagements. L'enjeu écologique de notre temps, cet "événement anthropocène", sera donc au départ des réflexions : parce qu'il ouvre bien sûr nombre de questionnements et de pistes d'investigation à l'enquête historique, mais aussi parce qu'il appelle des façons inédites de mobiliser la connaissance du passé pour éclairer le présent, pour dialoguer avec d'autres sciences comme pour contribuer (tout modestement) au débat social. De façon peut-être plus inattendue, on pourra aussi évoquer combien ce contexte - bouleversements majeurs et systémiques, incertitudes, impératif d'implication - suscite d'ébranlements... jusqu'à faire bifurquer le parcours intellectuel et l'orientation professionnelle de scientifiques

A BOLD signature of eyeblinks in the visual cortex.

International audienceWe are usually unaware of the brief but large illumination changes caused by blinks, presumably because of blink suppression mechanisms. In fMRI however, increase of the BOLD signal was reported in the visual cortex, e.g. during blocks of voluntary blinks (Bristow, Frith and Rees, 2005) or after spontaneous blinks recorded during the prolonged fixation of a static stimulus (Tse, Baumgartner and Greenlee, 2010). We tested whether such activation, possibly related to illumination changes, was also present during standard fMRI retinotopic and visual experiments and was large enough to contaminate the BOLD signal we are interested in. We monitored in a 3T scanner the eyeblinks of 14 subjects who observed three different types of visual stimuli, including periodic rotating wedges and contracting/expanding rings, event-related Mondrians and graphemes, while fixating. We performed event-related analyses on the set of detected spontaneous blinks. We observed large and widespread BOLD responses related to blinks in the visual cortex of every subject and whatever the visual stimulus. The magnitude of the modulation was comparable to visual stimulation. However, blink-related activations lay mostly in the anterior parts of retinotopic visual areas, coding the periphery of the visual field well beyond the extent of our stimuli. Blinks therefore represent an important source of BOLD variations in the visual cortex and a troublesome source of noise since any correlation, even weak, between the distribution of blinks and a tested protocol could trigger artifactual activities. However, the typical signature of blinks along the anterior calcarine and the parieto-occipital sulcus allows identifying, even in the absence of eyetracking, fMRI protocols possibly contaminated by a heterogeneous distribution of blinks

Pupil dynamics during bistable motion perception.

International audiencePupil size not only varies to changes in illumination but is also modulated by several cognitive factors, making it a potentially versatile physiological marker of cortical states. We recorded pupil dynamics while subjects continuously reported their bistable perception of ambiguous moving stimuli, plaids, and partially occluded rotating diamonds. We observed small (about 5% of surface change on average) but reliable pupil dilation around (-300 ms to 1.5 s) the button presses indicating the changes of percepts. We found that 70% of pupil dilation could be accounted for by the motor response. The remaining perceptual component was similar for spontaneously occurring transitions and transitions triggered by physical stimulus manipulations. Moreover, the amplitude of pupil modulation in the spontaneous condition was unrelated to the duration of each perceptual state. It is therefore unlikely that the mechanisms of endogenous perceptual bistability reflect in the pupil. In addition, we measured a clear constriction of the pupil after blinks (about 8% of surface change on average). As pupil changes have the potential to entail retino-cortical activity, their monitoring in studies of visual processing could prove worthwhile

Entre certitude des désastres environnementaux et incertitudes socio-politiques, quel rôle pour les scientifiques ? L'expérimentation de l'Atelier d'écologie politique

International audienc

Nature Humaine. L’être humain est-il écocidaire par nature ?

International audienc