Line bisection under an attentional gradient induced by simulated neglect in healthy subjects
- 作者：Parampal Grewal ; Jayalakshmi Viswanathan ; Jason J.S. Barton ; jasonbarton@shaw.ca ; Linda J. Lanyon
- 关键词：Conjunction search ; Ocular fixation ; Attention
- 刊名：Neuropsychologia
- 出版年：2012
- 期刊代码：205_00283932
- 类别：med
- 出版时间：May, 2012
- 卷：50
- 期：6
- 页码：1190-1201
- 文件大小：1354 K
摘要
Whether an attentional gradient favouring the ipsilesional side is responsible for the line bisection errors in visual neglect is uncertain. We explored this by using a conjunction-search task on the right side of a computer screen to bias attention while healthy subjects performed line bisection. The first experiment used a probe detection task to confirm that the conjunction-search task created a rightward attentional gradient, as manifest in response times, detection rates, and fixation patterns. In the second experiment subjects performed line bisection with or without a simultaneous conjunction-search task. Fixation patterns in the latter condition were biased rightwards as in visual neglect, and bisection also showed a rightward bias, though modest. A third experiment using the probe detection task again showed that the attentional gradient induced by the conjunction-search task was reduced when subjects also performed line bisection, perhaps explaining the modest effects on bisection bias. Finally, an experiment with briefly viewed pre-bisected lines produced similar results, showing that the small size of the bisection bias was not due to an unlimited view allowing deployment of attentional resources to counteract the conjunction-search task's attentional gradient. These results show that an attentional gradient induced in healthy subjects can produce visual neglect-like visual scanning and a rightward shift of perceived line midpoint, but the modest size of this shift points to limitations of this physiological model in simulating the pathologic effects of visual neglect.