Behavioral Contrast and the Peak Shift: Effects of Extended Discrimination Training¹

Behavioral contrast and the peak shift, two widely observed phenomena in experiments on successive discrimination learning, were shown to disappear during extended discrimination training. This finding and an analysis of the conditions under which behavioral contrast and the peak shift occur suggested that both phenomena were by‐products of emotional responses that resulted from response suppression and that their disappearance after extended discrimination training could be attributed to the dissipation of such emotional responses.