Can free-viewing perceptual asymmetries be explained by scanning, pre-motor or attentional biases?
Can free-viewing perceptual asymmetries be explained by scanning, pre-motor or attentional biases?
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DOI：
10.1016/s0010-9452(08)70645-2
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发表时间：
2002-04-01
期刊：
影响因子：
3.6
通讯作者：
Roberts, GR
中科院分区：
文献类型：
--
作者：
Nicholls, MER;Roberts, GR
对刺激的左侧和右侧之间的相对大小的判断通常向左侧包含的特征加权。这种知觉偏差可能是以下因素造成的：（a）从左向右的扫描偏差，（B）右半球的运动前激活，或者（c）左半球的空间注意偏差。这些解释知觉不对称的相对优点进行了调查。在实验1中，英语和希伯来语的读者作出了两个左/右镜像反转的亮度梯度（灰度任务）的亮度判断。尽管不同的阅读/扫描习惯，两组都表现出一种模糊的感知偏差。英语和希伯来语的读者也进行了线平分任务。扫描偏差的控制方法是要求参与者跟随标记从左到右或从右到左移动，然后在到达线中点时停止。尽管控制了扫描，但在两组中均观察到了显著性偏倚。实验2中，在灰度刺激之前呈现周边空间线索。与左侧和中性线索相比，英语阅读者对右侧线索的偏好减少。右侧线索可能克服了先前存在的非注意力偏见。在这两个实验中，前运动激活控制双手反应。尽管有这种对照，但在整个研究中观察到了显著偏倚。这些数据支持注意偏向对扫描和前运动激活的解释。是否单方面半球激活提供了一个足够的帐户，这种注意力的偏见进行了讨论。
Judgments of relative magnitude between the left and right sides of a stimulus are generally weighted toward the features contained on the left side. This leftward perceptual bias could be the result of, (a) left-to-right scanning biases, (b) pre-motor activation of the right hemisphere, or (c) a left hemispatial attentional bias. The relative merits of these explanations of perceptual asymmetry were investigated. In Experiment 1, English and Hebrew readers made luminance judgements for two left/right mirror-reversed luminance gradients (greyscales task). Despite different reading/scanning habits, both groups exhibited a leftward perceptual bias. English and Hebrew readers also performed a line bisection task. Scanning biases were controlled by asking participants to follow a marker as it moved left-to-right or right-to-left and then stop it as it reached the midpoint of the line. Despite controlling scanning, a leftward bias was observed in both groups. In Experiment 2, peripheral spatial cues were presented prior to the greyscales stimuli. English readers showed a reduction in the leftward bias for right-sided cues as compared to left-sided and neutral cues. Right-side cues presumably overcame a pre-existing leftward attentional bias. In both experiments, pre-motor activation was controlled using bimanual responses. Despite this control, a leftward bias was observed throughout the study. The data support the attentional bias account of leftward perceptual biases over the scanning and pre-motor activation accounts. Whether or not unilateral hemispheric activation provides an adequate account of this attentional bias is discussed.