Mechanisms of Object Recognition Revealed by Subliminal Visual Priming

Moshe Bar

Massachusetts General Hospital, NMR Center
Department of Psychology, Harvard University

Abstract:
The cortical mechanisms associated with conscious, reportable object recognition were studied using functional Magnetic Resonance Imaging (fMRI). Participants were required to recognize pictures of masked familiar objects that were presented very briefly, randomly and repeatedly. Objects which were not recognized in a certain presentation could still be recognized in a later attempt even under identical conditions, a phenomenon termed “subliminal visual priming” (Bar & Biederman, 1998, 1999). An event-related fMRI design allowed a selective comparison of the activity elicited by trials in which subjects were able to recognize the objects, compared with trials in which they could ‘almost’ recognize the objects. A ventro-temporal visual region was found that was consistently modulated by conscious perception of object identity. As subjects gained more information regarding an object’s identity, activity in the temporal lobe intensified and propagated anteriorly. The results reported here provide new insights regarding the dynamics and localization of processes unique to the moment of explicit object recognition, as well as processes which immediately proceed and follow that moment.

The lecture will take place:

in the Lecture Hall, Room 203, 44 Cummington St.
on Monday, January 24, 2000
at 1:00 pm