Research Article Receptive Fields for Flexible Face Categorizations

ABSTRACT—Examining the receptive fields of brain signals can elucidate how information impinging on the former modulates the latter. We applied this time-honored ap-proach in early vision to the higher-level brain processes underlying face categorizations. Electroencephalograms in response to face-information samples were recorded while observers resolved two different categorizations (gender, expressive or not). Using a method with low bias and low variance, we compared, in a common space of information states, the information determining behavior (accuracy and reaction time) with the information that modulates emergent brain signals associated with early face encoding and later category decision. Our results provide a time line for face processing in which selective attention to diagnostic information for categorizing stim-uli (the eyes and their second-order relationships in gender categorization; the mouth in expressive-or-not categorization) correlates with late electrophysiological (P300) activity, whereas early face-sensitive occipito-temporal (N170) activity is mainly driven by the contra-lateral eye, irrespective of the categorization task. One of the most pressing issues in relating brain function to perception and cognition concerns the functional interpretation of brain responses to complex visual stimuli. Although it is obvious that visual stimuli elicit brain signals, it is a challenge to narrow down the relevant visual features that modulate the signal, and to relate these to the behavior of the observer. For example, single-cell studies concerned with the mechanisms of visual categorization have established that infero-temporal neurons respond specifically to the sight of complex objects such as faces and hands (Desimone, Albright, Gross, & Bruce