On the modularity of face recognition: the riddle of domain specificity.

The present paper focuses on the modular attributes of face recognition, defined in terms of domain specificity. Domain specificity is examined by looking into the innate nature of face recognition, the special effects related to the recognition of inverted faces, the specificity of electrophysiological responsivity to facial stimuli, and the specific impairment in face recognition associated with localized brain damage. Converging evidence from these sources seems to consistently show that face recognition is not qualitatively unique, as it proceeds in a manner similar to the recognition of other visuospatial objects. However, it seems to be special in that it may involve specific mechanisms dedicated to face recognition. Among infants, differential responsivity to faces and to other objects in terms of age of onset, attraction and course of development, seems to indicate the operation of a special process. Unusual inversion effects in face recognition might be due to the special expertise that humans develop for recognizing upright faces. Face-selective single unit responses in the monkey's brain implies the existence in the visual system of cells which are exclusively dedicated to the processing of facial stimuli. Finally, in prosopagnosia localized brain damage is linked to a specific inability to recognize familiar faces. Taken together, the data seem to show that some elements in the process of face recognition are domain specific, and in that sense, modular.