The role of marking when reward is delayed.

Abstract

Two-choice spatial discrimination by rats is enhanced if a salient stimulus marker occurs immediately after every choice response and again after a delay interval (Lieberman, McIntosh & Thomas, 1979). Three experiments further explore this effect. Experiment 1 found that the second marker is unnecessary. Experiment 2 found that a marker presented before a response is as effective as one presented after. Both effects could be explained in terms of markers focusing attention on subsequent cues. Experiment 3, however, found that markers after choice enhance learning even when no discriminative cues are present following the marker. Markers thus appear to initiate both a backward search through memory and attention to subsequent events; both processes help to identify events that might be related to the unexpected marking stimulus.

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

“…For example, extensive use of brief stimuli in second-order schedules comprises a major subset of the literature on conditioned reinforcement (e.g., de Lorge, 1971;Stubbs & Cohen, 1972;see Gollub, 1977, andStubbs, 1971, for reviews). Also, recent experiments have shown that brief ("marking") stimuli presented following the occurrence of either response in a two-alternative situation followed by a delay facilitates acquisition of the reinforced (i.e., "correct") response (Lieberman, Davidson, & Thomas, 1985; Thomas, 1979; Thomas, Lieberman, McIntosh, & Ronaldson, 1983). Procedurally, however, the experiments reported here more closely resemble the procedures used in trace autoshaping with pigeons (e.g., Kaplan, 1984;Kaplan & Hearst, 1982;Lucas, Deich, & Wasserman, 1981).…”

Teaching Children with Autism when Reward is Delayed. The Effects of Two Kinds of Marking Stimuli

“…More specifically, we sought to compare the effectiveness of marked-before and marked-after procedures in bridging a delay to reinforcement in a receptive labeling task. There is evidence from the animal learning literature that both types of procedure can effectively bridge such delays (Thomas et al, 1983) but, although we have previously demonstrated the effectiveness of a marked-after procedure using children with autism (Grindle & Remington, 2002;in press), no studies to date have evaluated the impact of marked-before procedures with human participants in an applied setting.…”

“…Thomas, Lieberman, McIntosh, and Ronaldson (1983) acknowledged that this possibility is closely linked to a common experience in human memory: When people experience an event of special importance they often have vivid memories for what they did after that event as well as memories of what happened before (e.g., Brown & Kulik, 1977). Evidence for pre-response marking is, moreover, already available from the animal discrimination learning literature.…”

“…Compared to the no-marker control condition, both marked-before and marked-after procedures facilitated learning, confirming that marking stimuli may enhance memory for subsequent events as well as preceding ones. Thomas et al (1983) concluded that a marker can facilitate learning either by drawing attention to the response just emitted, thereby enhancing acquisition of the relation between the correct response and reinforcement, or by focusing attention on subsequent discriminative stimuli, enabling better recall of the chosen stimulus at the time of reinforcement.…”

“…Evidence for pre-response marking is, moreover, already available from the animal discrimination learning literature. Thomas et al (1983) compared rate of learning of a simple two-choice discrimination task when rats received a white noise marking stimulus either before making a choice response, immediately afterwards, or not at all. Compared to the no-marker control condition, both marked-before and marked-after procedures facilitated learning, confirming that marking stimuli may enhance memory for subsequent events as well as preceding ones.…”