Department of Psychology, Ludwig-Maximilians-University, Munich, Germany.
Department of Psychology, Ludwig-Maximilians-University, Munich, Germany.
Cortex. 2018 Apr;101:60-72. doi: 10.1016/j.cortex.2017.12.024. Epub 2018 Jan 31.
Patients with unilateral, parietal brain damage frequently show visual extinction, which manifests in a failure to identify contralesional stimuli when presented simultaneously with other, ipsilesional stimuli (but full awareness for single stimulus presentations). Extinction reflects an impairment of spatial selective attention, leaving basic preattentive processing unaffected. For instance, access to bilaterally grouped objects is usually spared in extinction, suggesting that grouping occurs at a stage preceding (in the patients: abnormally biased) spatial-attentional selection. Here, we reinvestigated this notion by comparing (largely between participants, but also within a single-case participant) conditions with objects that varied in their dominant direction of grouping: from the attended to the non-attended hemifield (data from Conci et al., 2009) versus from the non-attended to the attended hemifield (new data). We observe complete absence of extinction when shape completion extended from the attended hemifield. By contrast, extinction was not diminished when object groupings propagate from the unattended hemifield. Moreover, we found the individual severity of the attentional impairment (assessed by a standard "inattention" test) to be directly related to the degree of completion in the unattended hemifield. This pattern indicates that grouping can overcome visual extinction only when object integration departs from the attended visual field, implying, contrary to many previous accounts, that attention is crucial for grouping to be initiated.
单侧顶叶脑损伤患者常出现视觉忽视，即当对侧刺激与同侧其他刺激同时呈现时无法识别对侧刺激（但对单个刺激呈现有完全意识）。忽视反映了空间选择性注意的损伤，而基本的前注意加工不受影响。例如，在忽视中，通常可以访问双侧分组的物体，这表明分组发生在（在患者中：异常偏向）空间注意选择之前的阶段。在这里，我们通过比较具有不同分组主导方向的物体的条件（主要是在参与者之间，也在单个案例参与者内）来重新研究这一概念：从注意到非注意的半视野（来自 Conci 等人的数据，2009 年）与从非注意到注意的半视野（新数据）。当形状完成从注意的半视野延伸时，我们观察到完全没有忽视。相比之下，当物体分组从非注意的半视野传播时，忽视并未减少。此外，我们发现注意力损伤的个体严重程度（通过标准的“注意力不集中”测试评估）与非注意半视野中的完成程度直接相关。这种模式表明，只有当物体整合离开注意视野时，分组才能克服视觉忽视，这意味着与许多先前的解释相反，注意力对于分组的启动至关重要。
