Séminaire du 9 mars 2012

Thomas J. McKeeff présentera "Temporal Processing Limitations of Visual Object Processing"

• Intervenant : Thomas J. McKeeff
• Laboratoire : Harvard University, Department of Psychology
• Date prévue : 9 mars 2012 à 13h-14h
• Lieu : salle 106, 1er étage, bâtiment BSHM
• Titre : Temporal Processing Limitations of Visual Object Processing
• Abstract : The human visual system is surprisingly quick in some circumstances and stunningly slow in others. People can readily perceive a face, an object, or a scene within a single glimpse, yet detecting a target presented within a stream of successive distractors can prove to be quite difficult. What accounts for these temporal limitations in vision, especially with respect to object recognition? Using rapid serial visual presentation (RSVP), subjects were presented with a successive stream of objects at varying temporal rates and had to discriminate which of two pre-specified targets appeared in the sequence. Behavioral results indicated that increasing the familiarity of an item led to faster processing, whereas increasing the visual complexity of an object did not impair the efficiency of object processing. Another experiment indicated that visual expertise with an object category affected the efficiency of object processing. Greater perceptual competition was found to occur between objects of expertise (i.e., cars and faces in car experts), suggesting that non-face objects of expertise rely on similar processing mechanisms as face processing. These effects of familiarity and expertise indicate that the temporal efficiency of object processing strongly depends on high-level knowledge acquired about objects. To explore the neural basis of these processing limitations, fMRI data were collected to characterize the temporal tuning properties of ventral visual areas implicated in object recognition. The preferred temporal rate of individual visual areas was found to decline at successively higher levels of the visual hierarchy, perhaps suggesting that recognition performance might be limited by the poor temporal capacity of high-level object-selective areas. Overall, the temporal processing limitation for recognizing objects appears largely dependent on object-specific processes, rather than limits at earlier stages of visual processing.