Stimulus similarity and retroactive interference and facilitation in monkey short-term memory.

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Two prominent theories of proactive interference in animal memory predict that the effects of varying the interval between the interfering and to-be-remembered stimulus in a delayedmatching-to-sample paradigm ought to be comparable to the effects of manipulating the retention interval. To assess this prediction, monkeys were tested in a situation in which a sample was presented, followed by a variable intersample interval, whereupon a second sample was presented. After a delay interval, a choice test was given between the two stimuli that had served as samples. The correct choice was always the most recently presented sample stimulus, and the initial sample of a sequence provided a potential source of proactive interference. In two experiments, delay interval altered performance, whereas interstimulus interval had little or no effect. In a third experiment, using a small set of sample stimuli, intertrial interval altered proactive interference, but again interstimulus interval had no effect. One way of accounting for these data is in terms of distinct short-and long-term memory processes. 553As interest in short-term memory in animals continues, the number of stable empirical relationships uncovered steadily mounts. There is evidence, for example, that interference treatments alter memory for stimuli, responses, and reinforcers in a similar way (Maki, Moe, & Bierley, 1977) and produce the same pattern of results regardless of whether the subject population consists of pigeons, monkeys, or dolphins (D'Amato,1973;Herman, 1975;Roberts & Grant, 1976;Wilson, 1974;Worsham, 1975;Zentall & Hogan, 1974). Not surprisingly, there has been a concomitant interest in theories of animal memory, especially as they apply to interference phenomena.In discussing contrasting theories it will be useful to focus on a concrete experimental situation. Consider a delayed-matching-to-sample (DMTS) paradigm with two kinds of trials: (1) control trials, in which sample stimulus B is presented and, after a delay (retention) interval, a choice between stimulus A and stimulus B is given, with stimulus B rewarded; or (2) proactive interference trials, in which stimulus A is presented, then stimulus B is presented, and, after a delay interval, A and B are given on the choice test with stimulus B rewarded. Over an experimental session, A and B are rewarded equally often so that the correct solution is to choose the stimulus that has most recently served as a sample. Typically, performance on control trials surpasses that on inter- ference trials. Any memory theory must be able to address this basic finding.Although this paradigm seems to provide a natural tool for examining relationships between short-and long-term memory, the two most prominent theories of DMTS (D'Amato, 1973;Roberts & Grant, 1976) do not assume that performance reflects separate contributions from short-and long-term memory. Roberts and Grant, for example, proposed that longterm memory does not enter into pigeon DMTS performance. Instead, they assume that performance is contro...

Section: Discussionsupporting

confidence: 68%

Section: Methodsmentioning

confidence: 99%

Proactive interference in monkeys: Delay and intersample interval effects are noncomparable

Medin

1980

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“…One approach to this problem is to present an interpolated (and usually irrelevant) stimulus during all or some portion of the delay Waxman, 1977;Grant, 1976;Roberts & Grant, 1974). The contribution of comparison observation and choice (sometimes referred to as "response output") to overall performance is no less important (Medin, Reynolds, & Parkinson, 1980;Wright & Sands, 1981). One purpose of the present study, therefore, was to determine whether, and to what extent, extraneous stimulation would affect delayed matching when introduced during trial periods other than the delay interval.…”

mentioning

confidence: 99%

Interference of delayed matching to sample in pigeons: Effects of interpolation at different periods within a trial and stimulus similarity

Wright

Urcuioli

Sands

et al. 1981

Delayed matching-to-sample performance by pigeons was interfered with by displaying a monochromatic annulus around the center (sample) pecking key. The wavelength of the annulus and its point of interpolation within a trial were varied to determine possible differential effects on matching accuracy. Experiment 1 showed that delayed matching was most disrupted when the interference stimulus (570 nm, 630 DID, or achromatic white) appeared during the delay interval of a trial. Little if any disruption occurred when the interference stimulus was present during the sample and choice periods. The spectral relationship between the chromatic interference stimuli (570 and 630 nm) and the sample stimuli (570 and 630 nm) did not consistently influence the degree to which matching accuracy was affected in any interpolation condition. Experiment 2 found a similar pattern of within-trial effects when the interference stimulus was simply a change from a white achromatic annulus to a chromatic one. This finding indicates that illumination changes, such as the popular houselight variation, are not necessary to produce interference in delayed matching to sample. Even with illumination held constant, however, performance was not differentially sensitive to the similarity between interference and sample stimulus wavelengths. It is suggested that other experiments showing similarity effects in interference of delayed matching to sample were conducted in such a way that subjects confused the interfering stimuli with the samples. 595

“…Similarity of the interpolated stimuli to the sample and test stimuli, and saliency, familiarity, and complexity of the interpolated stimuli are not significant sources of retroactive interference (Grant & Roberts, 1976;Medin et al, 1980;Wright et al, 1981). Both ambient illumination and localized keylight illumination interpolated into the delay interval of delayed matching interfere with matching accuracy (Grant & Roberts, 1976).…”

mentioning

confidence: 99%

“…Retroactive interference is observed when matching accuracy on the interpolated test trials declines relative to matching accuracy on the baseline trials (Grant & Roberts, 1976;Medin, Reynolds, & Parkinson, 1980;Moise, 1970;Wright, Urcuioli, Sands, & Santiago, 1981).…”

mentioning

confidence: 99%

The role of interpolated stimuli in the retroactive interference of pigeon short-term memory

Kendrick

Rilling

1984

Theoretical accounts of retroactive interference in delayed matching-to-sample attribute decrements in performance to disruption of rehearsal or retrieval of a sample stimulus representation or an instruction of which test stimulus to peck. However, only two sources of retroactive interference have been identified so far: changes in illumination and electric shock. The present experiments sought evidence of additional sources of retroactive interference. Stimuli associated with variable interval (Vl), extinction (EXT), and differential reinforcement of other behavior (DRO) schedules were interpolated into the delays of delayed matching. The results of three experiments demonstrated that a stimulus associated with a VI schedule of reinforcement interferes with delayed matching but that an EXT-associated stimulus does not. Experiment 2 showed that a DRO-associated stimulus interferes with delayed matching. Additional analysis indicated that interference with delayed matching was a function of the degree to which the interpolated stimuli disrupted delay-interval behavior associated with accurate matching. These findings support the behavioral-context hypothesis, which states that response-produced stimuli arising from delay behavior provide the context necessary for accurate matching. Retroactive interference thus occurs to the extent that interpolated stimuli interfere with baseline delay behavior. 391Short-term memory in animals has been extensively studied in the delayed matching-to-sample paradigm. The successive delayed matching procedure is composed of four successive events: presentation ofthe sample stimulus, a delay interval, presentation of the test stimulus, and an intertrial interval. Responses during the test stimulus are correct or incorrect, that is, reinforced or not, conditional upon the relation between the previously presented sample stimulus and the current test stimulus (Wasserman, 1976). The task for the animal is to remember at the time of the test stimulus information based on the sample stimulus.Retroactive interference may be produced by interpolating events into the delay period. Retroactive interference is observed when matching accuracy on the interpolated test trials declines relative to matching accuracy on the baseline trials