TEMPORAL CONTROL ON INTERVAL SCHEDULES - WHAT DETERMINES THE POSTREINFORCEMENT PAUSE

On fixed-interval or response-initiated delay schedules of reinforceme nt, the average pause following food presentation is proportional to t he interfood interval. Moreover, when a number of intervals of differe nt durations occur in a programmed cyclic series, postreinforcement pa uses track the changes in interval value. What controls the duration o f postreinforcement pauses under these conditions? Staddon, Wynne, and Higa (1991), in their linear waiting model, propose control by the pr eceding interfood interval. Another possibility is that delay to reinf orcement, signaled by a key peck and/or stimulus change, determines th e subsequent pause. The experiments reported here examined the role of these two possible time markers by studying the performance of pigeon s under a chained cyclic fixed-interval procedure. The data support th e linear waiting model, but suggest that more than the immediately pre ceding interfood interval plays a role in temporal control.