Cognitive styles associats to autistiques and schizotypal traits: mecanist and mentalist approach of social cognition.

Facial identification is a key function of social adaptation. Although litterature provides with several hypotheses explaing facial-related information processing, these have still not been able to clearly explain the facial processing deficit related to pathologies such as autism and schizophrenia. Lately, Crespi & Badcock (2008) proposed the hypothesis that autistic and psychotic conditions might be located at the extreme ends of the same continuum. These two spectra would exhibit opposed cognitive phenotypes: autistic spectrum would tend to a « mechanistic » cognition and schizophrenia spectrum to a « mentalistic » cognition. Both poles, autism and psychosis, would present the extremes variations of a same dimension, respectively, "hyper-mechanistic" and "hyper-mentalistic". Indeed, even if both conditions cause a social cognition modification, they can be distinguished anatomically, developmentally, functionnally (IRM, EEG) and behaviourally. Apart from differences in terms of local versus global information processing, autistic and psychotic spectra feature facial information processing impairments, associated with anatomo-functional abnormalities of mirror neuron system, allegedly playing a role in social cognition. In addition, we note hemispheric organization differences and abnormalities of electrocortical dynamics.

These results suggest the existence of a « cognitive style » dimension, associated with an autism-psychosis continuum, whose extreme manifestations would lead to a modification of social cognition, in return associated with abnormal face-related information processing.

To test this hypothesis, this thesis project proposes two axes. The first axis will explore the association between autistic and schizotypal traits on one hand, and cerebral activation while processing configural facial information on the other hand.

The first stage aims at characterizing through questionnaires a sample of non-clinical individuals on the autism-psychosis continuum. This evaluation will be followed by different behavioural tasks (visual recognition, visual search, presentation in only one visual hemifield). Using stimuli representing faces, objects and face-like objects. These procedures will produce behavioural, hemispheric and electrocortical datas allowing both, the assessment of their variations related to stimuli type and their correlations with autistic and schizotypal traits.

A second research axis will explore the association between anatomic, functional and genetic cerebral dimensions using a clinical sample featuring genetic abnormalities, i.e. deletion or duplication of 16p11.2 locus, associated with an increased prevalence of, respectively, autistic and schizophrenic conditions. The cerebral function dimension will focus on gaze direction information processing in order to assess its impact on the activation of cerebral networks associated with social cognition, relatively to anatomic and genetic information. The results will show whether and to what extent autistic and schizophrenic cognitive styles belong to the same dimension, and maybe represent the two poles of this dimension.

Keywords: social brain, autism, psychosis, cognitive styles, face, object, face-like object.