ABSTRACT

Introduction

Impairments in visual search are a common symptom in visuospatial neglect (VSN). The severity of the lateralized attention bias in visual search tasks can vary depending on the number of distractors: the more distractors, the more targets are missed. However, little is known about how the number of targets affect search performance in VSN. The aim of the current study was to examine the effect of the number of targets on hit rate in VSN.

Methods

We included 23 stroke patients with right-brain damage and VSN, 55 with right-brain damage without VSN, and 49 with left-brain damage without VSN, all admitted for inpatient rehabilitation. In a visual search task, patients had to find and tap targets, presented along with non-targets. The location and number of targets varied from trial to trial, allowing the evaluation of the effects of number and location of targets on hit rate.

Results

VSN patients detected a lower percentage of targets when more targets were present. For patients with right-brain damage without VSN, adding targets only reduced the hit rate of the most contralesional target. No effect of number of targets on hit rate was seen in patients with left-brain damage. Additionally, VSN patients found less contralesional targets than ipsilesional targets, made more delayed revisits, and had an initial rightward bias when compared to the other groups. There were no differences in search time, search consistency, or immediate revisits between groups. There was a moderate positive relation between the hit rate asymmetry score in our search task and conventional paper-and-pencil VSN tasks, and neglect behavior in daily life.

Conclusions

In VSN patients, a higher number of targets reduces the hit rate. The reduced hit rate in visual search evoked by additional targets should be taken into account when assessing visual search in VSN.

中文翻译：

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在视空间忽略中，目标数量如何影响视觉搜索性能？

摘要

介绍

视觉搜索障碍是视觉空间疏忽（VSN）的常见症状。视觉搜索任务中偏侧注意力偏倚的严重程度可能会因干扰因素的数量而异：干扰因素越多，错过的目标越多。但是，对于目标数量如何影响VSN中的搜索性能知之甚少。当前研究的目的是检查目标数量对VSN中命中率的影响。

方法

我们纳入了23例右脑和VSN受损的脑卒中患者，55例没有VSN的右脑损伤和49例没有VSN的左脑损伤，所有这些患者均接受了住院康复。在视觉搜索任务中，患者必须找到并点击目标以及非目标。目标的位置和数量因试验而异，因此可以评估目标数量和位置对命中率的影响。

结果

当存在更多目标时，VSN患者检测到的目标百分比较低。对于没有VSN的右脑损伤患者，添加目标只会降低最不利的目标的命中率。在左脑损伤患者中未发现靶标数目对命中率的影响。此外，与其他组相比，VSN患者发现的对立目标数少于同侧目标，重访延迟时间更长，并且初始偏向右侧。两组之间的搜索时间，搜索一致性或立即重访没有差异。在我们的搜索任务和常规的纸笔VSN任务中，命中率不对称得分与日常生活中的忽视行为之间存在中等程度的正相关。

结论

在VSN患者中，更多的靶标会降低命中率。在评估VSN中的视觉搜索时，应考虑到由其他目标引起的视觉搜索命中率降低。