Snowden R J, Braddick O J
Department of Experimental Psychology, University of Cambridge, U.K.
Vision Res. 1990;30(8):1211-22. doi: 10.1016/0042-6989(90)90176-l.
Using random dot patterns we have compared performance on direction discrimination tasks for single and multi-step sequences of apparent motion at a range of displacement sizes. Performance was measured by varying the correlation between the frames. For "small" displacements we found that no improvement in performance occurs with stimulus duration (number of frames) if the movement of individual elements within the pattern was restricted to one step, whereas if elements undergo multiple steps, performance improves with duration. For "large" displacements, on the contrary, performance improves with increasing stimulus duration irrespective of whether individual elements are restricted to single steps. These results suggest that small and large displacements are processed in different ways. We review possible psychophysical and physiological correlates of this suggestion.
我们使用随机点图案，比较了在一系列位移大小下，单步和多步表观运动序列的方向辨别任务的表现。通过改变各帧之间的相关性来测量表现。对于“小”位移，我们发现，如果图案内单个元素的运动被限制为一步，那么随着刺激持续时间（帧数）的增加，表现不会得到改善；而如果元素经历多步运动，表现则会随着持续时间的增加而提高。相反，对于“大”位移，无论单个元素是否被限制为单步运动，表现都会随着刺激持续时间的增加而提高。这些结果表明，小位移和大位移是以不同方式进行处理的。我们回顾了这一观点可能存在的心理物理学和生理学关联。
