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Abstract:
Inferior temporal cortex (IT) neurons have large receptive
fields when a single effective object stimulus is shown against a
blank background, but have much smaller receptive fields when the
object is placed in a naturalscene. Thus, translation invariant
object recognition is reduced in natural scenes, and this may
help object selection. We describe a model which accounts for
this by competition within an attractor in which the neurons are
tuned to different objects in the scene, and the fovea has a
higher cortical magnification factor than the peripheral visual
field. Furthermore, we show that top-down object bias can
increase the receptive field size, facilitating object search in
complex visual scenes, and providing a model of object-based
attention. The model leads to the prediction that introduction of
a second object into a scene with blank background will reduce
the receptive field size to values that depend on the closeness
of the second object to the target stimulus. We suggest that
mechanisms of this type enable the output of IT to be primarily
about one object, so that the areas that receive from IT can
select the object as a potential target for action.
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