Timeout From Variable Time Reinforcement

Four rats were trained on an ascending and descending sequence of response independent variable-time reinforcement schedules ranging from 1-min to 16-min. A single lever press would turn off the stimuli associated with reinforcement and produce a timeout, during which reinforcement was not available. A second lever press would turn on the stimuli associated with reinforcement and reinstate the schedule. Although the performances were variable, several general results were obtained: the percentage of session time spent in timeout usually increased when the variable-time schedule was lengthened and decreased when the schedule was shortened; responses that produced timeouts generally occurred within the first minute after reinforcement on the smaller variable-time schedules, and spreading to the second minute after reinforcement on the larger variable-time schedules; timeout duration generally increased with schedule size, although modal timeout duration was less than 2 sec on all schedule sizes. The timeout responding appeared to be an adjunctive behavior in that it was sensitive to, but not directly controlled by, reinforcement. Stimulus change also appears to be an important determinant of timeout responding.