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Pigeons initially trained on a simultaneous discrimination of line orientation (S1) were subsequently transferred to a wavelength discrimination (S2). Three transfer procedures were employed. The abrupt-transfer Ss were “abruptly” switched from S1 to the S2 dimension. The stimulus-compounding Ss were trained on a compound stimulus consisting of S1 and S2 displayed in superimposition prior to the presentation of S2 alone. The stimulus-delay Ss were trained on a compound stimulus in which the presentation of the S1 component was delayed for successively longer intervals as a result of a correct response to the preceding trial. Stimulus-delay Ss transferred by responding to S2 prior to the presentation of S1 and the resulting formation of the compound. Ss transferred by the stimulus-compounding and the abrupt-transfer procedures displayed 5 and 10 times as many errors to the S2 dimension, respectively, as Ss receiving the stimulus-delay procedure.
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Pigeons acquired a successive delayed matching-to-sample task at a delay interval of 4 sec. Instructional stimuli were interpolated in the delay interval signaling the occurrence (R-cue) or nonoccurrence (F-cue) of comparison stimuli, a procedure modeled after the directed forgetting techniques commonly used in human memory studies. Accuracy on probe trials (in which comparison stimuli were presented following F-cues) was reduced relative to performance on standard training trials in which R-cues signaling the occurrence of comparison stimuli appeared in the same temporal location. The extent of the reduction in accuracy depended on the temporal location of the F-cues, the reduction being greater when the cue was more remote from the comparison stimuli. Examination of retention interval keypecking revealed a strong correlation between matching performance and retention interval responding. 相似文献
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Pigeons were given successive discrimination training in which pecking during a choice period when the key was white was either reinforced or not, depending upon the prior presence or absence of a discriminative stimulus, which was a two-element serial compound. The compound consisted of a keylight and food, with food presented second or first in a forward or backward pairing for different groups of pigeons. In Experiment 1, the sequence was an S+ indicating reinforced trials, while in Experiment 2, the sequence was an S? indicating nonreinforced trials. Following acquisition of discriminated operant behavior, a sequence generalization test was administered during which all possible orders of the two stimuli were presented on test trials prior to the onset of the choice period. The results showed that food overshadowed stimulus control by the color of the light on the key on the sequence-generalization test, independently of whether food was presented first or second during training and independently of whether food was associated with reinforcement or nonreinforcement. The similarity of results for the two experiments suggests that overshadowing occurs independently of whether the compound is a discriminative stimulus for reinforcement or nonreinforcement. Simultaneous presentation of elements of a compound stimulus is not necessary for overshadowing because the phenomenon was captured with sequentially presented stimuli. 相似文献
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Illumination effects during steady-state performance of discrimination tasks in animals have been well documented, whereas research on illumination effects during acquisition has been largely ignored. Exceptions to this rule are Wasserman’s (1973) autoshaping experiments and Maki’s (1979) successive discrimination experiment. The present experiment investigated the effects of illumination changes on acquisition of a conditional discrimination—delayed matching-to-sample (DMTS). Pigeons were used in a between-groups design which factorially varied house-light illumination, on or off, during the presentations of DMTS stimuli, the delay interval, and the intertrial interval (ITI). DMTS performance over five blocks of sessions was the dependent variable. The major result was the three-way interaction of sessions, the intertrial interval, and the DMTS stimuli. Constant illumination resulted in the highest discrimination ratios over the last four blocks of sessions. A constant dark condition did not differ from a condition with dark ITIs and illuminated stimulus presentations or from a condition with illuminated ITIs and dark stimulus presentations. The proffered explanation of these data emphasizes the disruptive effects of stimulus changes and Wasserman’s (1973) cue localization hypothesis. The loci of the stimulus change and cue localization effect are suggested to be either at the beginning of a trial or at the end of a trial. A pretrial account emphasizes the role of stimulus changes on the encoding of the sample stimulus, and a posttrial account emphasizes the role of stimulus changes during consolidation processing. 相似文献
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Two groups of pigeons were used to determine if different amounts of fixed-interval training with an added clock resulted in different local response rates when the clock was reversed. One group of seven pigeons received 120 reinforcements on a fixed-interval 90-sec schedule, while the other group received 1200 reinforcements. Following training, the added clock was reversed in extinction. Reversed scallops were obtained for both of the groups. Only the group with extended training showed an increase in responding during the previously reinforced segment of the interval. This suggests the development of greater temporal control with extended training. 相似文献
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Previous research in directed forgetting in pigeons has focused on the effect of single forget cues (F-cues) interpolated within the retention interval in delayed matching-to-sample (DMTS). The present series of experiments focuses on the ability of a remember cue (R-cue) to cancel the effects of a previously presented forget cue both when the forget cue occurs within the retention interval and when the forget cue precedes sample presentation. In the first experiment, an R-cue decreased the effect of an F-cue within the same retention interval in successive DMTS if the R-cue immediately followed the F-cue, but not if the second cue was delayed until the end of the retention interval. In Experiment 2, the double-cue effect was extended to choice DMTS. In addition, when a novel stimulus replaced the R-cue in the double-cue probe trials, matching performance was not restored, indicating that through its conditioning history the R-cue had gained control over memory processes in a direction opposite to that of the F-cue. Experiment 3 presents evidence that presample R- and F-cues can also effectively gain control over matching performance. Matching to R-cued samples was superior to matching to F-cued samples. When F-cued samples were followed immediately by R-cues, matching performance was not restored to R-cue levels, suggesting differential encoding of the R-cued and F-cued samples. 相似文献
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