Responding of Pigeons Under Variable‐interval Schedules of Unsignaled, Briefly Signaled, and Completely Signaled Delays to Reinforcement

Abstract

In Experiment 1, three pigeons' key pecking was maintained under a variable-interval 60-s schedule of food reinforcement. A 1-s unsignaled nonresetting delay to reinforcement was then added. Rates decreased and stabilized at values below those observed under immediate-reinforcement conditions. A brief stimulus change (key lit red for 0.5 s) was then arranged to follow immediately the peck that began the delay. Response rates quickly returned to baseline levels. Subsequently, rates near baseline levels were maintained with briefly signaled delays of 3 and 9 s. When a 27-s briefly signaled delay was instituted, response rates decreased to low levels. In Experiment 2, four pigeons' responding was first maintained under a multiple variable-interval 60-s (green key) variable-interval 60-s (red key) schedule. Response rates in both components fell to low levels when a 3-s unsignaled delay was added. In the first component delays were then briefly signaled in the same manner as Experiment 1, and in the second component they were signaled with a change in key color that remained until food was delivered. Response rates increased to near baseline levels in both components, and remained near baseline when the delays in both components were lengthened to 9 s. When delays were lengthened to 27 s, response rates fell to low levels in the briefly signaled delay component for three of four pigeons while remaining at or near baseline in the completely signaled delay component. In Experiment 3, low response rates under a 9-s unsignaled delay to reinforcement (tandem variable-interval 60 s fixedtime 9 s) increased when the delay was briefly signaled. The role of the brief stimulus as conditioned reinforcement may be a function of its temporal relation to food, and thus may be related to the eliciting function of the stimulus.

Delayed reinforcement: Effect of a brief signal on behavior maintained by a variable-ratio schedule

“…Employing this methodology, several researchers (e.g., Lattal, 1984;Richards, 1981) have found response rates to be much higher if the delay interval is signaled rather than unsignaled. Schaal and Branch (1988) reported a similar finding with a delay signal that did not persist for the entire delay interval. In fact, immediate reinforcement anddelayed reinforcement of either 3 or 9 sec produced comparable response rates when only the first .5 sec of the delay interval was signaled; responding was reduced substantially when the entire 3-or 9-sec delay interval was unsignaled.…”

“…Although some sort of counterbalancing could easilyhave beenemployed, our firstconcernwas to replicate Schaal and Branch's (1988) findings. Thus, rather thanrisk potentialcarryover effects once the signal had been directly paired with the food and presumably become a strong conditioned reinforcer, we decided to present the brief-signal conditions in an order that decreased the likelihood that behavior observed in later phases could be attributed to the signal's becoming a stronger conditioned reinforcer in earlier phases.…”

“…In fact, immediate reinforcement anddelayed reinforcement of either 3 or 9 sec produced comparable response rates when only the first .5 sec of the delay interval was signaled; responding was reduced substantially when the entire 3-or 9-sec delay interval was unsignaled. A .5-sec signal did not prevent decreases in responding with a 27-sec delay, but a subsequent study (Schaal & Branch, 1990) showed that the impact of even this delay duration could be lessened by increasing the delay signal's duration.In the present experiment, we examined the generality of the brief-signal results obtained by Schaal and Branch (1988) with a 3-sec delay of reinforcement. There were three major concerns: the type of delay signal , the temporallocation of the signal, and the underlying schedule of reinforcement.…”

“…In the present experiment, we examined the generality of the brief-signal results obtained by Schaal and Branch (1988) with a 3-sec delay of reinforcement. There were three major concerns: the type of delay signal , the temporallocation of the signal, and the underlying schedule of reinforcement.…”

“…The question of whether or not a similar effect would occur with an offkey stimulus seemed especially relevant in view of the extensive autoshaping literature (e.g., Hearst & Jenkins, 1974;Locurto, Terrace, & Gibbon , 1981). A second concern was whether Schaal and Branch's (1988) results depended on the signal occurring at the very beginning of the delay interval. To address this issue, we manipulated the temporal location of the signal within the delay interval.…”