Jaekl Philip M, Harris Laurence R
Centre for Vision Research, York University, Toronto, Ontario, Canada.
Neurosci Lett. 2007 May 7;417(3):219-24. doi: 10.1016/j.neulet.2007.02.029. Epub 2007 Feb 11.
The perceived time of occurrence of a visual stimulus may be shifted towards the onset of an auditory stimulus occurring a short time later. The effect has been attributed to auditory-visual temporal integration although an unknown portion of the shift may be explained by the different processing times of visual and auditory stimuli. Here, perceived onset time is measured in a novel way that separates and compares the magnitude of these effects. Participants observed either a sequence consisting of a visual stimulus followed by an auditory stimulus and then another visual stimulus or the reverse. The temporal location of the second stimulus was varied systematically between the onset of the first and third stimuli, which were separated by a fixed duration. Two timescales were used: a short timescale that allowed for auditory-visual temporal integration to occur, and a long timescale that did not. Psychometric curves were fitted for both timescales, to the percentage the first interval was perceived is shortest, as a function of first interval duration. For the long timescale condition the point of subjective equality (PSE) of the two interval lengths was consistent with the different processing latencies. When visual and auditory stimuli occurred within 125 ms significant additional shifting of the PSE occurred. These results indicate that temporal integration shifts the perceived timing of a visual stimulus by an amount much larger than can be explained differential processing latencies.
视觉刺激的感知发生时间可能会向稍后出现的听觉刺激的起始时间偏移。这种效应被归因于视听时间整合，尽管这种偏移的未知部分可能是由视觉和听觉刺激的不同处理时间所解释的。在这里，感知起始时间是以一种新颖的方式测量的，该方式分离并比较了这些效应的大小。参与者观察了两种序列：一种是由视觉刺激 followed by an auditory stimulus 然后再是另一个视觉刺激组成的序列，另一种是相反的序列。第二个刺激的时间位置在第一个和第三个刺激的起始时间之间系统地变化，第一个和第三个刺激之间间隔固定时长。使用了两个时间尺度：一个短时间尺度，允许视听时间整合发生；另一个长时间尺度，则不允许。针对两个时间尺度，将第一个间隔被感知为最短的百分比作为第一个间隔持续时间的函数，拟合了心理测量曲线。对于长时间尺度条件，两个间隔长度的主观相等点（PSE）与不同的处理延迟一致。当视觉和听觉刺激在125毫秒内发生时，PSE出现了显著的额外偏移。这些结果表明，时间整合使视觉刺激的感知时间发生的偏移量，远大于可由不同处理延迟所解释的量。
