Kewley-Port D, Pisoni D B
J Acoust Soc Am. 1984 Apr;75(4):1168-76. doi: 10.1121/1.390766.
Previous studies have reported that rise time of sawtooth waveforms may be discriminated in either a categorical-like manner under some experimental conditions or according to Weber's law under other conditions. In the present experiments, rise time discrimination was examined with two experimental procedures: the traditional labeling and ABX tasks used in speech perception studies and an adaptive tracking procedure used in psychophysical studies. Rise time varied from 0 to 80 ms in 10-ms intervals for sawtooth signals of 1-s duration. Discrimination functions for subjects who simply discriminated the signals on any basis whatsoever as well as functions for subjects who practiced labeling the endpoint stimuli as " pluck " and "bow" before ABX discrimination were not categorical in the ABX task. In the adaptive tracking procedure, the Weber fraction obtained from the jnds of rise time was found to be a constant above 20-ms rise time. The results from the two discrimination paradigms were then compared by predicting a jnd for rise time from the ABX discrimination data by reference to the underlying psychometric function. Using this method of analysis, discrimination results from previous studies were shown to be quite similar to the discrimination results observed in this study. Taken together the results demonstrate clearly that rise time discrimination of sawtooth signals follows predictions derived from Weber's law.
先前的研究报告称，在某些实验条件下，锯齿波波形的上升时间可以以类似分类的方式进行辨别，而在其他条件下则可根据韦伯定律进行辨别。在本实验中，采用了两种实验程序来检验上升时间辨别能力：语音感知研究中使用的传统标记和ABX任务，以及心理物理学研究中使用的自适应跟踪程序。对于持续时间为1秒的锯齿波信号，上升时间以10毫秒的间隔从0变化到80毫秒。在ABX任务中，那些基于任何依据简单辨别信号的受试者的辨别函数，以及那些在ABX辨别之前将端点刺激标记为“拨奏”和“拉奏”的受试者的函数，都不是分类性的。在自适应跟踪程序中，从上升时间的差别阈限获得的韦伯分数在上升时间超过20毫秒时被发现是一个常数。然后，通过参考潜在的心理测量函数，根据ABX辨别数据预测上升时间的差别阈限，对两种辨别范式的结果进行了比较。使用这种分析方法，先前研究的辨别结果被证明与本研究中观察到的辨别结果非常相似。综合来看，结果清楚地表明，锯齿波信号的上升时间辨别遵循从韦伯定律得出的预测。
