Event-related brain potentials during selective attention to depth and form in global stereopsis.

To elucidate the discriminating processes of surface depth and boundary form in global stereopsis, event-related brain potentials (ERPs) were investigated by the detection of combinations of the attributes in random sequences. The attentional relevance of depth or form was associated with selection negativities (SNs) over the lateral occipito-temporal regions initiating at about 200 ms post-stimulus. The initial SNs were elicited irrespective of relevance to the other feature; the following parts increased only for stimuli with crossed disparity having the relevant dimension of the other feature, suggesting the independent selection of stereoscopic depth and form followed by the perceptual integration into an object.