A Comparison of Signaled and Unsignaled Delay of Reinforcement

Abstract

Pigeons were trained on either a variable-interval 60-second schedule, or on a schedule that differentially reinforced responses that were spaced at least 20 seconds apart. The birds were then exposed to several durations of reinforcement delay, with comparisons between signaled and unsignaled delays. Although unsignaled delays of 5 and 10 seconds produced large decreases in response rate, signaled delays of up to 10 seconds produced only moderate decreases in response rates. In addition, some subjects responded more rapidly with a .5 or 1.0 second duration of unsignaled delay than with immediate reinforcement. These response rate changes occurred regardless of whether the rate of reinforcement concomitantly decreased or increased.Key words: reinforcement delay, variable-interval schedule of reinforcement, differentialreinforcement-of-low-rates schedule of reinforcement, key peck, pigeonsOne of the most widely discussed parameters of reinforcement is delay of reinforcement (e.g., Bolles, 1975;Hulse, Deese, & Egeth, 1975;Mackintosh, 1974). While much of the early empirical and theoretical work examined the manner in which delayed reinforcement influenced the learning of new behavior or discriminations (e.g., Grice, 1948;Perin, 1943;Spence. 1947;Wolfe, 1934), the more recent emphasis, especially in the area of operant conditioning, has been on how it affects behavior maintained by various schedules of reinforcement (e.g., Azzi, Fix, Keller, & Rocha e Silva, 1964;Dews, 1960;Ferster, 1953;Ferster & Hammer, 1965;Morgan, 1972;Pierce, Hanford, & Zimmerman, 1972;Silver & Pierce, 1969;Sizemore & Lattal, 1977Williams, 1976).Delayed reinforcement actually refers to a collection of very different manipulations. For example, the delay period may be signaled or unsignaled; if signaled, the opportunity to respond may or may not be withdrawn during the delay. In addition, responding during the delay interval may be nonfunctional or it may be penalized, e.g., by resetting the delay interval. Given this diversity, it would be surprising if all such manipulations had identical effects. Yet, few researchers have actually compared different types of delayed reinforcement suggestion, Richards and Hittesdorf (1978) found that a 10-sec signaled delay maintained much higher response rates than a 10-sec unsignaled delay when pigeons' responding was reinforced according to a VI schedule.The purpose of the present experiment was to assess the generality of Richards and Hittesdorf's finding by comparing the effects of various durations of signaled and unsignaled delay. To assess the generality of any effect, the present experiment also included two different types of reinforcement schedules. Variable-interval 60-sec and differential-reinforcement-oflow-response-rates (DRL) 20-sec schedules were selected because it seemed possible that delayed reinforcement might produce similar effects on the behavior maintained by these 145 1981, 35,[145][146][147][148][149][150][151][152] NUMBER 2 (MARCH)

Operant variability when reinforcement is delayed

“…This was found whether low, middle, or high variability was reinforced. This result is consistent with those from many other studies (e.g., Odum et al, in press;Reilly & Lattal, 2004;Richards, 1981;Shahan & Lattal, 2005). As expected, postreinforcement time-outs had small and inconsistent effects on response rate.…”

“…Delays of reinforcement-intervals between the last response in a trial and reinforcement-were systematically manipulated. We predicted that rates of responding would slow as delay durations increased (see, e.g., Reilly & Lattal, 2004;Richards, 1981) but that the reinforcement contingencies would maintain different levels of variability in the three groups (see, e.g., Doughty & Lattal, 2001;Grunow & Neuringer, 2002). Finally, we sought to test for an interaction between reinforcement delay and reinforcement contingency.…”

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

“…In subsequent studies (e.g. , Azzi, Fix, Keller, & Rocha e Silva , 1964;Ferster, 1953;Lattal, 1984;Pierce, Hanford, & Zimmerman, 1972;Richards, 1981;Richards & Hittesdorf, 1976;Sizemore & Lattal, 1978;Williams, 1976), researchers have examined effects on responding maintained by intermittent reinforcement. Currently, the most common methodology involves pigeons, keypecking, food reward, and a variable-interval schedule.…”

“…Currently, the most common methodology involves pigeons, keypecking, food reward, and a variable-interval 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.…”

The role of response-reinforcer correlation in signaled reinforcement effects

“…In contrast, a signal-induced enhancement in response rate results if a long interval (e.g., 3 sec) is scheduled between the response that precedes food and food delivery (Richards, 1981;Schachtman, Reed, & Hall, 1987;Williams & Heyneman, 1982). Schachtman et al (1987) interpreted these findings as indicative of the importance of the contiguity between response and reinforcement in determining when signaling reinforcement will produce an attenuation of performance (i.e., instrumental overshadowing) or an enhancement of responding (i.e., instrumental potentiation).…”