The effect of multiple S-delta periods on responding on a fixed-interval schedule: 3. Effect of changes in pattern of interruptions, parameters and stimuli.

Pigeons responding under fixed-interval schedules of reinforcement were interrupted by S(Delta) periods during the course of the intervals. Whether intervals were interrupted by 1, 2, or 5 S(Delta) periods, the general scalloped pattern of FI responding persisted. Parameter values up to 27(3/4) hr for the FI and 2(3/4) hr for the individual S(Delta) interruptions were studied. The results further weaken the hypothesis that the FI pattern of responding depends crucially on control of responding by continuously chained mediating behavior.