Spatial biases in visual selection: effects of competition and inhibition

Yukovsky, Julia (2012). Spatial biases in visual selection: effects of competition and inhibition. University of Birmingham. M.Phil.

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Abstract

Objective: To determine whether visual selection for a target in patients with spatial deficits in attention is affected by (a) attending to a socially significant distractor, and (b) prior inhibition of a search-relevant feature. Methods: In the first study, 4 patients with left neglect, 4 patients with extinction, and 4 controls were assessed. A shape target was presented in the ipsilesional or contralesional field, and a distractor face was presented at fixation. Attractive faces created greater interference with the response to contralesional targets in the group of right-parietal patients with neglect. In the second study, 5 parietal patients with neglect and 8 patients without neglect were asked to search for a colour pop-out target. Patients with neglect showed inhibition or facilitation when the target or distractor feature, respectively, had been rejected. Conclusions: Socially significant stimuli with salient attributes exacerbate the local spatial bias in parietal patients with neglect and interfere with response selection when the target is in the contralesional hemifield. In addition, the process of inhibitory tagging is preserved in neglect patients, and affects the detection of novel information on both the ipsilesional and contralesional sides of space. The implications of these results for understanding visual selection are discussed.

Type of Work:

Thesis (Masters by Research > M.Phil.)

Award Type:

Masters by Research > M.Phil.

Supervisor(s):