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Abstract:
Abstract: Visual extinction has been characterized as an
imbalance in the temporal processing of inputs favoring
ipsilesional events. This view was supported by the finding that
simply presenting a line to an extinction patient resulted in the
report of motion within the line away from the ipsilesional side of
space. These data reveal an early temporal processing advantage
ipsilesionally. In a second experiment the line was preceded (45,
105, 165, 225, 285, 345, 405 or 465 milliseconds) by a priming cue
on either one or both ends of the line. The reported dimension was
either the direction of motion within the line or, to assess
extinction, the number of cues presented. Although robust
extinction occurred, when a single cue was presented motion was
reported away from that cue regardless of the side of presentation.
In contrast, when two cues were presented there was no difference
in the frequency of motion away from either cue early in the time
course whereas motion away from the ipsilesional cue dominated
later in the timecourse. Together, these experiments suggest an
early spatial and temporal deficit (E1), and differential
processing in a later object-based competition process (E2).
Although signals from competing objects were clearly registered
early on, there was a later bias toward reporting only ipsilesional
objects.
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