EFFECTS OF RESPONSE-REINFORCER RELATIONS ON THE MAINTENANCE OF COORDINATED RESPONDING UNDER SCHEDULES OF SIMULTANEOUS REINFORCEMENT

The effects of response-reinforcer relations on coordinated responding were investigated. Coordinated responding was defined as two lever presses, one by each rat that occurred within 500 ms of one another. Four conditions were arranged in an ABCB design. Coordinated responding was reinforced according to a fixed-ratio 6 (FR 6) schedule in Condition A. In Condition B, a response by each rat was required, independent of their temporal proximity, to produce water delivery under a variable-interval schedule. Condition C was a replication of Condition B, except that coordinated responding was required for reinforcer deliveries. All conditions involved simultaneous reinforcement, that is the rats received access to reinforcers at the same time. The results extended previous findings by demonstrating the requirement of coordinated responses to produce reinforcement affected both coordinated response rates and the proportion of such responses relative to the total responses in a session, in that both measures were higher in Conditions A and C than in Condition B. There also was control of the temporal distribution of coordinated responding by the type of schedule (FR or VI): A “break-and-run” pattern was observed under the FR schedule, and a constant response rate was observed under the VI schedule.

Effect of Prior Rewarded Goal-Box Placements on Small-Trials Partial-Reinforcement Effect

The study was designed to test three hypotheses of the small-trials partial-reinforcement effect. Seventy-two hooded rats received either continuous reward or partial reward for 6 acquisition trials in a runway. Prior to acquisition, an equal number of Ss in each schedule condition were given 0, 5, or 10 rewarded goal-box placements. A strong small-trials partial-reinforcement effect was evident. There was an effect of placements on both initial and terminal acquisition-performance, indicating that rg–sg was preconditioned to goal-box cues. However, this preconditioned rg–sg failed to influence persistence of responding during extinction. The extinction results are contrary to two frustration analyses but do not contradict an analysis of aftereffects.

Extinction of Observing Behavior

The probability of observing-key responses for pigeons trained to observe during a mixed-fixed ratio 50 fixed-interval 2-min. schedule of reinforcement decreased sharply when only the mixed schedule or the corresponding multiple schedule was programmed. First session observing-key response probability values were greater in the mixed-schedule condition, suggesting that the mixed-schedule stimulus set the occasion for pecking the observing-key following reinforcement offset. In the mixed-schedule condition, the results for one bird suggested that stimuli associated with the early portion of each component controlled a relatively high response-rate; and, when the component was fixed-interval, stimuli arising from the organism's behavior controlled a pause which followed more than 50 responses. This post-response pause contributed to the determination of a relatively low response-rate in the fixed-interval component of the mixed-schedule.