Chieffi S
Dipartimento di Fisiologia Umana e Funzioni Biologiche Integrate Filippo Bottazzi, II Università di Napoli, Italy.
Neurology. 1996 Oct;47(4):1004-8. doi: 10.1212/wnl.47.4.1004.
There is an upward bias in bisecting radial and vertical lines under visual guidance. We investigated whether illusory visual factors might contribute to a previously reported representational upward bias in this task. In two experiments, subjects performed a line-bisection task along the three orthogonal axes (horizontal, radial, vertical). In Experiment 1, the stimuli consisted of a line terminated at each end by two equal- or different-sized bars. In Experiment 2, the stimuli were formed by a line terminated by two equal- or different-sized directional labels: SOPRA ("top") and SOTTO ("bottom"). The results showed a bisection bias towards the smaller bar (Experiment 1) and the smaller directional label (Experiment 2) on all three spatial axes, supporting the existence of an illusory visual effect. Contrary to a previous report, the data failed to show any representational (semantic) bias related to directional label meaning. These findings suggest that perceptual/attentional factors play a significant role in normal subjects' upward bias.
在视觉引导下平分径向线和垂直线时存在向上偏差。我们研究了虚幻的视觉因素是否可能导致先前报道的该任务中存在的代表性向上偏差。在两个实验中，受试者沿着三个正交轴（水平、径向、垂直）执行线平分任务。在实验1中，刺激物由一条线组成，线的两端由两个大小相等或不同的条终止。在实验2中，刺激物由一条线组成，线的两端由两个大小相等或不同的方向标签终止：SOPRA（“顶部”）和SOTTO（“底部”）。结果表明，在所有三个空间轴上，都存在朝着较小条（实验1）和较小方向标签（实验2）的平分偏差，这支持了虚幻视觉效应的存在。与先前的报道相反，数据未能显示出与方向标签含义相关的任何代表性（语义）偏差。这些发现表明，感知/注意力因素在正常受试者的向上偏差中起重要作用。
