Snowden R J, Braddick O J
Kenneth Craik Laboratory, Department of Experimental Psychology, University of Cambridge, U.K.
Vision Res. 1991;31(5):907-14. doi: 10.1016/0042-6989(91)90156-y.
The temporal properties of human visual motion detection were explored. Experiment 1 measured thresholds for speed discrimination as a function of stimulus duration. Thresholds fell asymptotically to a Weber fraction around 0.06 over a period of approx. 100 msec, with faster speeds asymptoting at slightly shorter stimulus durations. A second experiment required subjects to discriminate a pattern that was modulated between two speeds from one which remained at a constant speed. The minimum depth of the modulation required to make this judgement was found to be equivalent to a Weber fraction of 0.3 at low modulation rates, around five times greater than when the velocities were presented in isolation (expt 1). At some higher modulation rate performance dramatically declined. The modulation rate at which this occurred decreased with stimulus speed, and increased with stimulus size. The results of expt 1 seem consistent with the known properties of primary motion sensors, while the results of the latter experiments may arise from a later stage integrating the output of these primary motion sensors.
对人类视觉运动检测的时间特性进行了探索。实验1测量了速度辨别阈值作为刺激持续时间的函数。在大约100毫秒的时间内，阈值渐近下降至约0.06的韦伯分数，速度越快，在稍短的刺激持续时间内达到渐近值。第二个实验要求受试者区分在两种速度之间调制的模式和保持恒定速度的模式。发现做出这种判断所需的最小调制深度在低调制率下相当于0.3的韦伯分数，大约是速度单独呈现时（实验1）的五倍。在某些较高的调制率下，性能急剧下降。发生这种情况的调制率随刺激速度降低，并随刺激大小增加。实验1的结果似乎与初级运动传感器的已知特性一致，而后一个实验的结果可能源于整合这些初级运动传感器输出的后期阶段。
