Previous research has shown that prism adaptation (prism adaptation) can ameliorate several symptoms of spatial neglect after right-hemisphere damage. But the mechanisms behind this remain unclear. Recently we reported that prisms may increase leftward awareness for neglect in a task using chimeric visual objects, despite apparently not affecting awareness in a task using chimeric emotional faces (Sarri et al., 2006). Here we explored potential reasons for this apparent discrepancy in outcome, by testing further whether the lack of a prism effect on the chimeric face task task could be explained by: i) the specific category of stimuli used (faces as opposed to objects); ii) the affective nature of the stimuli; and/or iii) the particular task implemented, with the chimeric face task requiring forced-choice judgements of lateral ‘preference’ between pairs of identical, but left/right mirror-reversed chimeric face tasks (as opposed to identification for the chimeric object task). We replicated our previous pattern of no impact of prisms on the emotional chimeric face task here in a new series of patients, while also similarly finding no beneficial impact on another lateral ‘preference’ measure that used non-face non-emotional stimuli, namely greyscale gradients. By contrast, we found the usual beneficial impact of prism adaptation (prism adaptation) on some conventional measures of neglect, and improvements for at least some patients in a different face task, requiring explicit discrimination of the chimeric or non-chimeric nature of face stimuli. The new findings indicate that prism therapy does not alter spatial biases in neglect as revealed by ‘lateral preference tasks’ that have no right or wrong answer (requiring forced-choice judgements on left/right mirror-reversed stimuli), regardless of whether these employ face or non-face stimuli. But our data also show that prism therapy can beneficially modulate some aspects of visual awareness in spatial neglect not only for objects, but also for face stimuli, in some cases.
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机译：先前的研究表明，棱镜适应（棱镜适应）可以减轻右半球受损后空间疏忽的几种症状。但是其背后的机制仍不清楚。最近我们报告说，尽管显然不会影响使用嵌合情感面孔的任务中的意识，但棱镜可能会增加使用嵌合视觉对象进行任务时的向左意识（Sarri et al。，2006）。在这里，我们通过进一步测试是否可以通过以下方式解释对嵌合面部任务任务缺乏棱镜效应的潜在原因，从而探究了结果明显差异的潜在原因：i）所用刺激的具体类别（与对象相对的面部）； ii）刺激的情感性质；和/或iii）实施特定任务，其中嵌合面部任务需要对成对的相同但左/右镜像反转的嵌合面部任务之间的横向“偏好”进行强制选择判断（与识别嵌合对象任务相反） ）。我们在一系列新患者中复制了以前的棱镜对情感嵌合面部任务没有影响的模式，同时也发现对使用非面部非情绪刺激的另一种横向“偏爱”措施（即灰度）没有任何有益影响渐变。相比之下，我们发现棱镜适应（棱镜适应）对某些常规的忽略测量方法具有通常的有益影响，并且对至少一些面对不同面部任务的患者进行了改进，需要明确区分面部刺激的嵌合或非嵌合性质。 。新发现表明，棱镜疗法不会改变被忽视的空间偏见，正如没有正确或错误答案的“侧向偏好任务”所揭示的那样（需要对左/右后视镜反向刺激进行强迫选择判断），无论这些疗法是否使用面部或非面部刺激。但是我们的数据还显示，棱镜疗法可以在某些情况下有益地调节空间忽略的视觉意识的某些方面，不仅对于物体，而且对于面部刺激。
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