Signal Functions in Delayed Reinforcement

Key pecking by 4 pigeons was maintained by a multiple schedule consisting of two variable-interval 60-s schedules wherein each food presentation followed a nonresetting 27-s delay that was either briefly signaled at its outset or completely signaled. Brief-signal duration was adjusted so that response rates maintained by the briefly and completely signaled delays of reinforcement were similar. In general, acute administration of small to intermediate doses (0.3 to 3.0 mg/kg) of cocaine produced either small increases in response rates in both components or no change, and larger doses (5.6 to 13.0 mg/kg) decreased response rates. Chronic (i.e., daily) cocaine administration (10.0 mg/ kg) resulted in tolerance to the rate-decreasing effects in both components. Cocaine's effects were generally similar whether delays were completely or briefly signaled. Discontinuation of cocaine administration and subsequent removal of the delay signals also had similar effects in both components of the multiple schedule. Taken together, these results are consistent with the view that the two types of delay signals were equally effective in maintaining responding during the variableinterval schedules.Key words: signaled delay of reinforcement, conditioned reinforcement, cocaine, tolerance, variableinterval schedule, key peck, pigeonsThe purpose of the present experiment was to study the effects of acute and chronic (i.e., daily) cocaine administration on responding maintained by briefly and completely signaled delays to reinforcement. Key pecking by 4 pigeons was maintained by a multiple schedule consisting of two variableinterval (VI) 60-s components, wherein each reinforcer followed a 27-s delay. In one component the delay was briefly signaled by a change in key color at its beginning; in the other component the delay was completely signaled. Roughly equal response rates were established in the two components of the multiple schedule via manipulation of the brief-signal duration. Cocaine was administered acutely and then chronically to determine whether drug effects on performance would differ for the two types of signaling arrangements.Cocaine was chosen for study in the present experiment because it has been suggested that this drug and other psychomotor stimu-

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confidence: 97%

Effects of Cocaine on Briefly Signaled Versus Completely Signaled Delays to Reinforcement

Walker

Branch

1996

“…The procedures used by Lattal (1977, 1978), Ferster (1953), and Lattal (1984) seem to parallel delays to reinforcement as they occur in natural settings. At times (possibly rarely) delays to reinforcement are unsignaled (e.g., an elevator call button with no indicator light).…”

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confidence: 99%

“…These results may be contrasted with those of Ferster (1953), who found that rates of key pecking under a VI 60-s schedule could be maintained at baseline levels even with a 60-s delay of reinforcement, provided the delay was signaled (by a chamber blackout) and lengthened gradually. More recently, Lattal (1984), employing a modified VI schedule (which generated approximately 0.50 to 0.70 reinforcers per minute), found that when 20-s delays were signaled by a blackout rates of key pecking were maintained at values nearer immediate reinforcement baseline levels than when delays were unsignaled or when blackouts were not explicitly positively correlated with delays.…”

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confidence: 99%

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

Schaal

Branch

1988

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.

“…In other studies, a stimulus change (such as handling by the experimenter or a brief tone or light) has been correlated with the start of the delay interval (e.g., Lett, 1975;Logan, 1952). Such stimuli may enhance response maintenance through conditioned reinforcing or other mediating effects, precluding interpretations of response acquisition strictly in terms of delayed reinforcement (e.g., Lattal, 1984;Schaal & Branch, 1988;Spence, 1947).…”

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confidence: 99%

Acquisition of a Spatially Defined Operant With Delayed Reinforcement

Critchfield

Lattal

1993

Self Cite

Two experiments investigated the role of an immediate, response-produced auditory stimulus during acquisition, via delayed reinforcement, of a response selected to control for possible unprogrammed, operandum-related sources of response feedback. Experimentally naive rats were exposed to a delayedfood reinforcement condition, specifically a tandem fixed-ratio 1 differential-reinforcement-of-otherbehavior 30-s schedule. The response was defined as breaking a photocell beam located near the ceiling at the rear of the operant conditioning chamber. In Experiment 1, rates of photobeam breaking by each rat increased from near zero, regardless of the presence or absence of a tone that immediately followed the response initiating the delay interval. Though not essential, the tone facilitated response acquisition and resulted in more efficient response patterns at stability. Experiment 2 demonstrated that photobeam-breaking response rates under the delayed reinforcement contingency exceeded those in a preceding baseline condition in which no food was delivered. In addition, upon introduction of the delayed reinforcement procedure, correspondence between response patterns and the requirements of the reinforcement schedule increased over baseline levels in the absence of a food contingency. Together with a previous report of Lattal and Gleeson (1990), the present results suggest that response acquisition with delayed reinforcement is a robust phenomenon that may not depend on a mechanically defined response or an immediate external stimulus change to mediate the temporal gap between response and reinforcer.