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| Environmental Variables in Animal Short-Term Memory |
| Monday, May 31, 2010 |
| 2:00 PM–3:20 PM |
| Lone Star Ballroom Salon F (Grand Hyatt) |
| Area: EAB; Domain: Experimental Analysis |
| Chair: Yusuke Hayashi (University of Kansas) |
| Abstract: In psychology, the problem of “memory” often appears as the problem of action at a temporal distance, in which a stimulus at one point in time affects behavior occurring at another. From a behavioral perspective, “memory” can be best understood in terms of retention and loss of stimulus control as a function of time (Branch, 1977). That is, remembering as discriminative behavior is said to be under delayed stimulus control (White, 1985). This nature of remembering as discriminative behavior suggests that such behavior is subject to both stimulus and reinforcement variables in the environment. Along these lines, the first study investigated the development of steady-state performance as a function of extended exposure to the delayed matching-to-sample (DMTS) task. The second study investigated the relation between temporal distance of the sample as a stimulus dimension and other environmental variables such as sample duration and intertrial interval. The third study investigated effects of ordinal position of fixed- and variable-ratio schedules on DMTS performance. Finally, using a titrating DMTS procedure as a procedural variant, the fourth study investigated effects of several environmental variables (e.g., time-out periods for incorrect responding) on performance in the procedure. |
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| Quantification of the Development of Steady-State Performance Under a Delayed Matching-to-Sample Procedure |
| BRIAN D. KANGAS (University of Florida), Meredith S. Berry (University of Florida), Marc N. Branch (University of Florida) |
| Abstract: This study was designed to examine basic features of a commonly employed experimental procedure called delayed matching-to-sample. Six pigeons were exposed for an extended period to a standard delayed matching-to-sample task with multiple delays in each session. Accuracy and log-d measures were used to quantify the development of performance under each of 5 delay values, 0, 2, 4, 8 and 16-s. Exposure to 60 trials per daily session (i.e., 12 trials of each delay) was conducted for 300 sessions (18,000 total trials; 3,600 trials per delay). Near-perfect accuracy developed relatively quickly under the shorter delays, but increases in accuracy under the longer delays, which occurred for all subjects, sometimes were not observed until 100-150 sessions had passed. Accuracy at the longest delays was still increasing after 300 sessions. A review of the literature combined with these results suggests that the development of steady-state performance under a typical delayed matching to sample task with multiple delays may require a great deal of exposure. |
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| Time as an Environmental Variable in Delayed Matching-to-Sample |
| K. GEOFFREY WHITE (University of Otago) |
| Abstract: In delayed matching to sample, choices of comparison stimuli are reinforced when the comparison corresponds to a sample presented at an earlier time. The temporal distance of the sample, along with its other physical attributes such as hue, is a dimension of the sample, just as spatial distance can be a dimension of the sample. Data are described which support the analogous effects of temporal and spatial distance. The effects of temporal distance of the sample are relative to the context of other temporal variables such as sample duration and intertrial interval. The data support the view that remembering is a discrimination determined by the reinforcement context and by environmental variables including the retention interval. |
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| Effects of Ordinal Position of Fixed- and Variable-Ratio Schedules on Delayed Matching-to-Sample Performance in Pigeons |
| YUSUKE HAYASHI (University of Kansas), Chata A. Dickson (New England Center for Children), Michael Perone (West Virginia University) |
| Abstract: The present study investigated effects of ordinal position of fixed- and variable-ratio schedules on delayed matching-to-sample performance. Three pigeons were trained on two conditional discriminations with green and white as sample and comparison stimuli in a delayed identity matching-to-sample procedure. The retention interval ranged between 0.5 to 13.5 s and varied within each session. Across phases, either a fixed- or a variable-ratio schedule was in effect that specified the number of trials that had to be completed correctly to deliver a food reinforcer. Throughout the study, a correction procedure was used such that a trial was repeated until a correct comparison stimulus was selected. Under the fixed ratio schedule, the duration of post-reinforcement pauses was the longest on the trials immediately following reinforcement. Overall, matching accuracy was lower on the trials immediately following reinforcement than on the subsequent trials. By contrast, both the duration of post-reinforcement pauses and matching accuracy were not systematically related to the ordinal position of the variable ratio schedule. |
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| The Impact of Environmental Factors on Short-Term Remembering in the Pigeon |
| Manish Vaidya (University of North Texas), JONATHAN E. FRIEDEL (University of North Texas), Caleb D. Hudgins (University of North Texas) |
| Abstract: Matching to sample procedures in which a delay is inserted between the offset of sample stimuli and the onset of comparison stimuli are known as delayed-match to sample (DMTS) procedures and are commonly used to study short-term remembering in a variety of populations. A great deal is known about environmental influences on DMTS performance. By comparison, less is known about environmental influences on performance in a variant of the DMTS procedure in which the delays between sample offset and comparison onset are adjusted as a function of an individual subject’s performance. In the current paper, we describe the effects of several procedural variables on TDMTS performance. Specifically, we report 1) the effects of time-out periods for incorrect responding; 2) the effects of randomly inserted “short-delay” trials; 3) the effects of adjusting the parameters by which delays titrated; and 4) the effects of observing response requirements on performance in the TDMTS procedure. The results suggest that performance under TDMTS procedures is sensitive to environmental factors. The data also show that ‘forgetting functions’ are not influenced by procedural manipulations that influence performance in the TDMTS procedure but would not be expected to influence remembering. |
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