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Abstract:
Abstract: The objective of the present study was to
investigate the influence of lower and higher-level factors on
saccadic eye movements in visual search in hemispatial neglect. Two
neglect patients (L.C. and E.R.) and 12 healthy controls had to
decide which of two target letters (H or T) was present in a
display of 4 stimuli. In condition 1 the target was simply
displayed without any distractors, whereas distractor similarity
increased from conditions 2 to 4. As expected the reaction times
(RTs) of the neglect patients were longer when targets appeared on
the left. Like the controls, E.R. made fast target directed
saccades in the single item condition and produced more saccades
than in condition 2 and 3. In contrast, L.C. made saccades in all
trials and was not influenced by presence or absence of
distractors. Additionally, both controls and patient E.R. directed
incorrect saccades towards similar distractor letters. This was not
the case for L.C. whose saccades were always distributed evenly
over the distractors. The experiment demonstrates the influence of
both lower and higher-level factors on saccadic eye-movements in
the control subjects and patient E.R. but no influence of either
factor in patient L.C.. This outcome would not have been apparent
with the assessment of reaction times only.
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