Conditioning history and the control of human avoidance and escape responding.

Inter-subject differences in response rates under free-operant avoidance and escape schedules are commonly obtained from humans. Data are presented which demonstrate that such differences can be controlled experimentally by giving subjects different conditioning histories. Subjects given a fixed-ratio history avoided and/or escaped from "point-loss periods" at higher rates than subjects given a differential-reinforcement-of-low-rates history. History related differences in response rates were maintained during 40 hr of escape responding. For low-rates history subjects, response rates under escape contingencies decreased as the rate of point-loss periods decreased.