Tappe T, Niepel M, Neumann O
Department of Psychology, University of Bielefeld, Germany.
Perception. 1994;23(3):335-47. doi: 10.1068/p230335.
The effect of the spatial frequency (SF) of visual gratings on reaction time (RT) and temporal-order judgment (TOJ) was examined in three experiments. In experiment 1 the visual stimuli were vertical sinusoidal gratings with SFs between 2 and 8 cycles deg-1 and the comparison stimulus in the TOJ task was a 2300 Hz tone. Whereas SF had a highly significant effect on RT, it left TOJ completely unaffected. To test whether this dissociation was due to the sharp (high SF) horizontal edges of the gratings, a second experiment was carried out with circular stimuli with no sharp edges. These stimuli did produce an effect of SF on TOJ, but it was significantly smaller than was the effect on RT. In experiment 3 we confirmed that this difference was not due to differences in grating orientation between the first two experiments. These findings (a) solve discrepancies between findings reported in the literature and (b) strongly suggest that RT and TOJ cannot be regarded as converging operations for determining 'visual latency'. This dissociation can best be accounted for by assuming that the output of early stimulus analysis can feed directly into the motor system (direct parameter specification), whereas the conscious representation that is used for TOJ is based on later integrative processes.
在三个实验中研究了视觉光栅的空间频率（SF）对反应时间（RT）和时间顺序判断（TOJ）的影响。在实验1中，视觉刺激是垂直正弦光栅，其空间频率在2至8周/度之间，TOJ任务中的比较刺激是2300赫兹的音调。虽然空间频率对反应时间有非常显著的影响，但对时间顺序判断完全没有影响。为了测试这种分离是否是由于光栅的锐利（高空间频率）水平边缘造成的，进行了第二个实验，使用没有锐利边缘的圆形刺激。这些刺激确实产生了空间频率对时间顺序判断的影响，但明显小于对反应时间的影响。在实验3中，我们证实这种差异不是由于前两个实验中光栅方向的差异造成的。这些发现（a）解决了文献中报道的研究结果之间的差异，（b）强烈表明反应时间和时间顺序判断不能被视为确定“视觉潜伏期”的趋同操作。这种分离最好通过假设早期刺激分析的输出可以直接输入到运动系统（直接参数指定）来解释，而用于时间顺序判断的有意识表征是基于后期的整合过程。
