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Abstract:
Abstract: In the present study we examined the interrelation
of semantic categorisation and spatial selective attention with
event-related potentials (ERPs). ERPs were recorded from 32
electrode sites to words presented in the left or right visual
field, while a letter-like mask was displayed in the respective
opposite visual field to prevent attention shifts to the
'unattended' items. The direction of selective attention was
clearly drawn to one visual field. Half of the targets were
therefore presented unattended and parafovealy. The subjects were
instructed to maintain central fixation. In the first part of the
experiment twenty-four subjects had to respond to animal names with
an underlined letter 'e'. Twelve subjects attended the left, twelve
the right visual field. In a second study with the same
experimental set-up the same subjects responded to animated items
on one of both sides. Eye-movements towards the attended visual
field were found in every condition, indicating that spatial
attention was directed towards the instructed visual field. A
significant difference was found for 'animals' and animated items
(targets) in comparison to nontargets for both the attended and the
unattended visual field. This was reflected in an enhanced
negativity between 500 and 1000 ms poststimulus onset. These
preliminary results indicate that semantic processing might occur
independent from spatial attention. It might be based on parafoveal
stimulus information and different attention resources.
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