Adaptation-level theory, anchor theory, and the peak-shift phenomenon

A study of the peak-shift phenomenon was conducted from the standpoint of adaptation level (AL) and anchor theory. 60 human Ss were divided into 6 groups - 3 control and 3 experimental. During a training period each S lifted 2 weights of 50 and 250, 100 and 300, or 150 and 350 gm. and was told to respond "same" or "different" by pressing the appropriate telegraph key during a forthcoming testing period, according to whether the weight he would lift was or was not one of the original two. Experimental Ss received discrimination training, in addition, with weights of 150, 200, and 250 gm. Following training, Ss were tested on 10 weights ranging from 50 to 500 gm. at 50-gm. intervals. The mean peaks for 4 of the 6 groups, 3 experimental and 1 control, were consistent with an AL-anchor interpretation.