Previous work has shown that gamma-band electroencephalogram oscillations recorded over the posterior cortex of infants play a role in maintaining object representations during occlusion. Although it is not yet known what kind of representations are reflected in these oscillations, behavioral data suggest that young infants maintain spatiotemporal (but not featural) information during the occlusion of graspable objects, and surface feature (but not spatiotemporal) information during the occlusion of faces. To further explore this question, we presented infants with an occlusion paradigm in which they would, on half of the trials, see surface feature violations of either a face or an object. Based on previous studies, we predicted higher gamma-band activation when infants were presented with a surface feature violation of a face, but not of an object. These results were confirmed. A further analysis revealed that whereas infants exhibited a significant increase in gamma during the occlusion of an object (as reported in previous studies), no such increase was evident during the occlusion of a face. These data suggest markedly different processing of objects and faces in the infant brain and, furthermore, indicate that the representation underpinned by the posterior gamma increase may contain only spatiotemporal information.
*Now at Swinburne University of Technology.