Remembering: The role of extraneous reinforcement

Abstract

In two experiments, pigeons' responding on an extraneous task was explicitly reinforced during delayed matching-to-sample trials. In Experiment 1, red or green sample stimuli were followed by retention intervals of 0.2, 1, 4, or 12 sec, during which pecks to a white center key were reinforced with 2.5-sec access to wheat according to extinction, variable-interval 30-sec, and variable-interval 15-sec schedules in different conditions. A proportion of .2, .5, .7, or .9 of subsequent red or green choice responses that matched the sample were reinforced with 3-sec access to wheat. The result was that increasing center key reinforcement, or reducing reinforcer probability, lowered overall accuracy. Initial discriminability fell, but with no change in the rate of forgetting. In Experiment 2, initial discriminability was affected by extraneous reinforcers that were contingent on center key pecking, but not by noncontingent reinforcers. A plausible conclusion is that initial discriminability decreases when reinforcers strengthen competing behaviors.

Contrast effects in response rate and accuracy of delayed matching to sample

“…First, the effects were evident in the steady state, unlike the probe-test results of Wilkie (1984), Blough (1998), and Nevin et al (2003). Second, reinforcers in the alternated component occurred outside the constant-component VI DMTS trials and thus were temporally distant from DMTS trials, unlike the reinforcers arranged by Wilkie, Blough, and Brown and White (2005c).…”

“…Thus, the results of Experiment 2 support the model, whereas those of Experiment 1 do not. It is not immediately obvious how the model can be adapted to account for that difference in outcomes, or for the various results reported by Wilkie (1984), Blough (1998), and Brown and White (2005c) with different procedures. Future research may identify those circumstances under which reinforcers that are extraneous to a discrimination task do or do not affect the accuracy of performance and thereby help to identify the mechanisms underlying the effects.…”

Forgetting from Short-Term Memory in Delayed Matching to Sample: A Reinforcement Context Model

“…For the present model, we assume that other behaviors extraneous to the task of remembering occur throughout the retention interval, whatever they are, and that they are rewarded by extraneous or other reinforcers, R o , following Herrnstein's (1970) supposition of extraneous reinforcement. In general, R o is a hypothetical entity, although it could be supplemented by experimenter-defined extraneous reinforcement, as Brown and White (2005b) …”

“…If the reduction in discriminability with increasing retention interval duration results from competition between reinforcers for completing the memory task and reinforcers for alternative or other behaviors, R o , then a reduction in the probability of reward for the memory task will result in a relatively greater influence of R o and, accordingly, a greater increase in the rate of forgetting. The rationale above was applied more specifically by Brown and White (2005b) to a delayed matching-to-sample task with pigeons, in which an extraneous task was interpolated in the retention interval. The extraneous task involved pecking the center key, with pecks rewarded according to variable interval (VI) schedules of VI 15 or VI 30 s, or not at all (Extinction or EXT).…”

Remembering as discrimination in delayed matching to sample: Discriminability and bias

“…In a conditional discrimination, in particular, the discriminated operant is a behavioral unit, subject to reinforcement in the same way that a simple operant is. Here, we argue that remembering in delayed matching to sample (DMTS), also a conditional discrimination, can be treated as a discriminated operant in which the relation between the sample stimulus and a choice response is a behavioral unit (Brown & White, 2005b;Sargisson & White, 2001;White, 2002).…”