Moshe Bar
Massachusetts General Hospital, NMR Center
Department of Psychology, Harvard University
will speak on
Mechanisms of Object Recognition Revealed by Subliminal Visual Priming
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
Hosted by the
Brain and Vision Research Laboratory