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Abstract:
Abstract: The ability of abrupt changes in the visual scene
to capture attention has been well documented by numerous studies
utilizing behavioral measures of task performance (e.g., Yantis,
1996). Previously, we used event-related potential (ERP) recordings
to show that abrupt visual changes (non-predictive "cues") produce
enhanced visual processing of subsequent, behaviorally-relevant
target stimuli (Hopfinger & Mangun, 1998). In the present
study, we further investigate how non-predictive cues may affect
the neural processing of task-irrelevant "probe" stimuli that do
not require any behavioral response. We found that the cues (the
appearance or disappearance of a set of 4 dots demarcating a
rectangle) captured attention to locations in space and produced an
enhancement of an early component of the visual ERP, the
extrastriate-generated P1, for the subsequent probe stimuli
appearing at that location. This enhancement was produced even
though the cue and probe stimuli were completely irrelevant to the
subject's task and was produced following both onset and offset
cues. These results provide evidence that visual processing can be
modulated as early as the extrastriate visual cortex in humans by
means of reflexive attentional mechanisms triggered by the
appearance or disappearance of visual objects.
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