Traitements analytiques et configural dans la reconnaissance des visages: Etude electrophysiologique chez le sujet normal (French and English text)

An enduring issue in face recognition research is whether face perception depends upon the processing of its global appearance or engages the processing of individual features and their configuration? On the one hand, the holistic view of face recognition assumes that face perception exclusively entails the extraction of a whole-face configuration. On the other hand, the relational view of face recognition emphasizes the joint contribution of an analytic mechanism based on the decomposition of the stimulus into its constituent parts and a configural mechanism based on the processing of the spatial relations among the features of a specific face.; The aim of this thesis is to specify the relative contribution of the analytic and holistic mechanisms during face part encoding. A systematic examination of this issue was conducted by using facial stimuli which minimized confusion between information pertaining to facial features (natural segments) and their spatial relations (arbitrary segments). Face matching experiments were conducted in normal subjects in order to examine the impact of different experimental manipulations on face part encoding through performance as well as electrophysiological measurements, in particular the occipito-temporal negative deflection around 170 ms associated with face processing.; In a first study designed to explore the influence of 'perceptual strategy' and 'facial context' on face part encoding, the results suggested that the basic constituents on which the analytic mechanism acts would be natural face segments, while configural information would be crucial to engage the holistic mechanism. Regarding the relative involvement of these mechanisms in face processing, our data provided evidence that it is not only a function of the physionomic value of the available facial input, but also of the encoding strategy involved in visual analysis.; In a second study, it was observed that stimulus inversion affects the processing of both arbitrary and natural parts. These results contradict the notion that the face inversion effect is caused by a forced switch from configural to componential processing.; To conclude, it appears that the analytic and holistic mechanisms are both involved at the structural encoding stage of face recognition. Our data also provided evidence that the visual system is able to encode the face configuration as well as to integrate face parts encoded individually and that these two processes are triggered independently by the relevant type of face input and the encoding strategy used in visual analysis. Taken together, these results contradict the holistic view of face recognition, but support the relational view of face recognition, according to which both an analytic and a holistic mechanism contribute to face recognition.