Patients with left unilateral spatial neglect (USN) typically place the subjective midpoint to the right of the objective centre. Based on the previous findings (e.g., Ishiai et al. 1989, Brain, 112, 1485), we hypothesized that the patients with left USN may see the representational image of a line that extends equally towards either side of the subjective midpoint depending not upon the information about the leftward extent. The present study tested whether patients with left USN would place the subjective midpoint at the centre of their mental representation of the line. The participants were 10 patients with left USN and 10 neurologically healthy controls. We devised a new ‘endpoint reproduction task’ using a computer display with a touch panel to seek the representational image when patients with left USN bisect lines and asked the participants to reproduce the location of the right or left endpoint after bisecting lines. The results showed that the representational image of the bisected line depends primarily on the location of the objective right endpoint, not on the location of the objective left endpoint in space. The analyses of the estimated right and left representational extents confirmed our hypotheses that patients with left USN would bisect a line seeing the representational line image that centred across their subjective midpoint. We believe that the findings of the present study with the use of the endpoint reproduction task will contribute to a better understanding of the visuospatial process underlying line bisection of patients with left USN.

中文翻译：

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左单侧空间忽视患者将一条线一分为二时的心理表征：一项具有端点再现任务的研究

左侧单侧空间忽视 (USN) 的患者通常将主观中点置于客观中心的右侧。基于先前的发现（例如，Ishiai 等人 1989，Brain, 112, 1485)，我们假设左侧 USN 患者可能会看到一条线的代表性图像，该线向主观中点的任一侧均等地延伸，这取决于有关左侧范围的信息。本研究测试了左侧 USN 患者是否会将主观中点置于他们对线的心理表征的中心。参与者是 10 名左侧 USN 患者和 10 名神经系统健康对照。我们设计了一种新的“端点再现任务”，使用带有触摸面板的计算机显示器来寻找左 USN 平分线患者时的代表性图像，并要求参与者在平分线后再现右端点或左端点的位置。结果表明，二等分线的代表性图像主要取决于目标右端点的位置，而不是目标左端点在空间中的位置。对估计的左右代表性范围的分析证实了我们的假设，即左侧 USN 患者将看到以主观中点为中心的代表性线图像一分为二。我们相信，本研究使用端点再现任务的结果将有助于更好地理解左侧 USN 患者线平分的视觉空间过程。对估计的左右代表性范围的分析证实了我们的假设，即左侧 USN 患者将看到以主观中点为中心的代表性线图像一分为二。我们相信，本研究使用端点再现任务的结果将有助于更好地理解左侧 USN 患者线平分的视觉空间过程。对估计的左右代表性范围的分析证实了我们的假设，即左侧 USN 患者将看到以主观中点为中心的代表性线图像一分为二。我们相信，本研究使用端点再现任务的结果将有助于更好地理解左侧 USN 患者线平分的视觉空间过程。