Varied Shock and Simple Escape
5 groups of rats were trained on an operant escape task under high, intermediate, or low shock conditions. Each of 3 groups received one of these intensities on all days and trials. The fourth group alternated between high and low shock intensities on consecutive days and the fifth group between high and low shock intensities randomly on consecutive trials within a day. High-intensity shock elicited faster escape responding than did low-intensity shock. Responding at a given shock level was similar regardless of the schedule of shock presentation (i.e., constant, alternated, or random). It was concluded that drive level on a given trial was the major determinant of performance.