Department of Psychology, University of Toronto, Toronto, Ontario, Canada.
Cognition. 2012 Aug;124(2):244-50. doi: 10.1016/j.cognition.2012.04.008. Epub 2012 May 24.
The present study investigated the mechanisms responsible for the difference between visual processing of stimuli near and far from the observer's hands. The idea that objects near the hands are immediate candidates for action led us to hypothesize that vision near the hands would be biased toward the action-oriented magnocellular visual pathway that supports processing with high temporal resolution but low spatial resolution. Conversely, objects away from the hands are not immediate candidates for action and, therefore, would benefit from a bias toward the perception-oriented parvocellular visual pathway that supports processing with high spatial resolution but low temporal resolution. We tested this hypothesis based on the psychophysical characteristics of the two pathways. Namely, we presented subjects with two tasks: a temporal-gap detection task which required the high temporal acuity of the magnocellular pathway and a spatial-gap detection task that required the spatial acuity of the parvocellular pathway. Consistent with our prediction, we found better performance on the temporal-gap detection task and worse performance on the spatial-gap detection task when stimuli were presented near the hands compared to when they were far from the hands. These findings suggest that altered visual processing near the hands may be due to changes in the contribution of the two visual pathways.
本研究旨在探讨负责观察者手部附近和远处刺激的视觉处理差异的机制。由于手附近的物体是行动的直接候选者，我们假设手部附近的视觉会偏向于支持高时间分辨率但低空间分辨率处理的大细胞视觉通路。相反，远离手的物体不是行动的直接候选者，因此，它们会受益于支持高空间分辨率但低时间分辨率处理的小细胞视觉通路的感知偏向。我们基于这两条通路的心理物理学特征来验证这个假设。具体来说，我们向被试呈现了两个任务：一个是需要大细胞通路高时间灵敏度的时间间隔检测任务，另一个是需要小细胞通路高空间灵敏度的空间间隔检测任务。与我们的预测一致，当刺激出现在手部附近时，被试在时间间隔检测任务上的表现更好，而在空间间隔检测任务上的表现更差。这些发现表明，手部附近的视觉处理可能会发生变化，这是由于两条视觉通路的贡献发生了变化。
