SELECTIVE SPATIAL ATTENTION IN PATIENTS WITH VISUAL EXTINCTION

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Abstract
The present study was designed to verify the attentional performance of patients with parietal lesions in the experimental condition in which they had to pay attention to 3 spatial positions located on the left, on the right and directly above the fixation stimulus (Experiment 1) and to only 1 of the 3 spatial positions at a time (Experiment 2). Twelve patients (6 subjects with right parietal lesions and 6 subjects without neurological deficits) participated in the experiment. The results of Experiment 1 showed that in patients with right parietal lesions the speed and accuracy of response to horizontally aligned stimuli increased gradually from right to left, whereas the control group showed only the effect due to the different retinal eccentricities of the 3 stimuli, that is, responses to central stimuli were faster and more accurate than responses to left and right stimuli. The results of Experiment 2 showed that both the neurological and control groups were faster to respond to central than to left and right stimuli, and that the neurological group was faster to respond to right that left stimuli, whereas no difference in RTs between two visual fields was obtained in the control group. Furthermore, when the patients had to respond to 3 spatial locations aligned horizontally (Experiment 1), the speed and accuracy of response to the right Stimulus were the same as when they had to focus attention on it (Experiment 2). These results showed that the focus of attention in patients with visual extinction is on the rightmost stimulus and that the increased attention to the right is accompained by a decreased attention to the left.