Timeout postponement without increased reinforcement frequency

Three experiments were conducted to examine pigeons' postponement of signal ed extinction periods (timeouts) from a schedule of food reinforcement when such responding neither decreased overall timeout frequency nor increased the overall frequency of food reinforcement. A discrete-trial procedure was used in which a response during the first 5 s of a trial postponed an othe rwise immediate 60-s timeout to a later part of that same trial but had no effect on whether the timeout occurred. During time-in periods, responses o n a second key produced food according to a random-interval 20-s schedule. In Experiment 1, the response-timeout interval was 45 s under postponement conditions and 0 s under extinction conditions (responses were ineffective in postponing timeouts). The percentage of trials with a response was consi stently high when the timeout-postponement contingency was in effect and de creased to low levels when it was discontinued under extinction conditions. In Experiment 2, the response-timeout interval was also 45 s but postponem ent responses increased the duration of the timeout, which varied from 60 s to 105 s across conditions. Postponement responding was maintained, genera lly at high levels, at all timeout durations, despite sometimes large decre ases in the overall frequency of food reinforcement. In Experiment 3, timeo ut duration was held constant at 60 s while the response-timeout interval w as varied systematically across conditions from 0 s to 45 s. postponement r esponding was maintained under all conditions in which the response-timeout interval exceeded 0 s (the timeout interval in the absence of a response). In some conditions of Experiment 3, which were designed to control for the immediacy of food reinforcement and food-correlated (time-in) stimuli, res ponding postponed timeout but the timeout was delayed whether a response oc curred or not. Responding was maintained for 2 of 3 subjects, suggesting th at behavior was negatively reinforced by timeout postponement rather than p ositively reinforced by the more immediate presentation of food or food-cor related (time-in) stimuli.