[lingtalks] Yaoda Xu Talk, Wed. Feb. 27 at 12pm

[Steven Ford]

The UCSD Department of Cognitive Science is pleased to announce a talk by

Yaoda Xu Ph.D.

Psychology Department
Yale University


Wednesday, February 27, 2008 at 12pm
Cognitive Science Building, room 003

"Dissociable parietal mechanisms supporting visual object individuation and 
identification"

Many everyday activities, such as driving on a busy street, require the 
encoding of distinctive visual objects from crowded scenes. Given resource 
limitations of our visual system, one solution to this difficult and 
challenging task is to first select individual objects from a crowded scene 
(object individuation) and then encode their details (object 
identification). Using functional magnetic resonance imaging (fMRI), I 
recently identified two distinctive parietal brain mechanisms that support 
these two stages of visual object processing. While the inferior 
intra-parietal sulcus (IPS) selects a fixed number of about 4 objects via 
their spatial locations, the superior IPS encodes the features of a subset 
of the selected objects in great detail. Thus the inferior IPS individuates 
visual objects from a crowded display and the superior IPS participates in 
subsequent object identification. Consistent with this theory, I will show 
that object individuation in the inferior IPS is sensitive to perceptual 
grouping cues between objects, and object identification in the superior 
IPS may play a key role in binding multiple independent object features 
together. These findings advance our understanding of the role of the 
parietal cortex in visual cognition and can explain deficits in object 
perception after bilateral parietal lesions in humans. These results also 
have significant implications to cognitive theories on visual object 
perception and can account for a number of (sometimes puzzling) behavioral 
findings as well as bridge studies on the development of object concepts in 
infants.
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