Department of Psychology, Dortmund University of Technology, Emil-Figge-Strasse, Dortmund, Germany.
Exp Brain Res. 2010 May;203(1):89-100. doi: 10.1007/s00221-010-2211-9. Epub 2010 Mar 24.
The human vision system appears to divide into two streams: a ventral stream from V1 to the inferior temporal cortex processing 'vision for perception', and a dorsal stream from V1 to the posterior parietal cortex processing 'vision for action'. Among other characteristics, it has been suggested that dorsal processing is effortless, unconscious, and not bearing on central cognitive resources implicated in ventral processing. The present study shows that a typical dorsal task (i.e., grasping an object) is subject to a classical indicator of capacity limitations in dual-task situations, the psychological refractory period (PRP) effect. In particular, response times to task 2 (the grasping task) increased the more the two tasks overlapped in time, i.e., the shorter the time interval between the stimuli of the two tasks was. As is also common in PRP experiments, response times to task 1 were largely unaffected by this variation. The PRP effect was obtained despite careful control of strategic response deferment, and peripheral overlap of response modalities that may have artificially created performance costs in previous studies. Altogether, the present results show that dorsal processing is subject to the same capacity limitations that can almost universally be found with simple cognitive tasks.
从 V1 到下颞叶皮层的腹侧流，用于处理“感知视觉”，以及从 V1 到后顶叶皮层的背侧流，用于处理“动作视觉”。除其他特征外，有人认为背侧处理是不费力气的、无意识的，不会影响到与腹侧处理相关的中央认知资源。本研究表明，一个典型的背侧任务（即抓取物体）受到双任务情况下能力限制的经典指标——心理不应期（PRP）效应的影响。具体来说，任务 2（抓取任务）的反应时间随着两个任务在时间上的重叠越多而增加，即两个任务的刺激之间的时间间隔越短。与 PRP 实验中常见的情况一样，任务 1 的反应时间基本上不受这种变化的影响。尽管对策略性反应延迟和可能在以前的研究中人为地产生了性能成本的反应模态的外周重叠进行了仔细的控制，但仍然得到了 PRP 效应。总之，本研究结果表明，背侧处理受到与简单认知任务中几乎普遍存在的相同能力限制的影响。
