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At least 127 records · Page 7Linked to original sources
PubMed1992

A table of d' for M-alternative odd-man-out forced-choice procedures.

There is a class of multiple-alternative forced-choice psychophysical procedures in which the subject is required to identify which one of a number of stimuli differs from the remaining stimuli, without having to consider the direction or sign of the difference. A table giving values of the discrimination index d' as a function of the proportion of correct responses in such odd-man-out procedures was generated by numerical simulation. The table covers experiments with 3 to 32 alternative stimuli.

Attention↗
PubMed1990

[Dependence of search activities on the probability of random execution of instrumental reaction].

The increase in rat search activity was found to develop in early stages of the learning when probability of random performance of instrumental reaction to light was equal to 0.25. This phenomenon was not depended on duration of conditioned signal and/or/of intersignal period at the invariable probability. The probability of random performance of instrumental reaction is suggested to determine search activity and to be able to influence leaning rate.

Animals↗
PubMed1990

Choice with uncertain outcomes: conditioned reinforcement effects.

Pigeons responded on concurrent chains with equal initial- and terminal-link durations. In all conditions, the terminal links of one chain ended reliably in reinforcement; the terminal links on the alternative chain ended in either food or blackout. In Experiment 1, the terminal-link stimuli were correlated with (signaled) the outcome, and the durations of the initial and terminal links were varied across conditions. Preference did not vary systematically across conditions. In Experiment 2, terminal-link durations were varied under different stimulus conditions. The initial links were variable-interval 80-s schedules. Preference for the reliable alternative was generally higher in unsignaled than in signaled conditions. Preference increased with terminal-link durations only in the unsignaled conditions. There were no consistent differences between conditions with and without a common signal for reinforcement on the two chains. In the first series of conditions in Experiment 3, a single response was required in the initial links, and the stimulus conditions during 50-s terminal links were varied. Preference for the reliable outcome approached 1.0 in unsignaled conditions and was considerably lower (below .50 for 3 of 5 subjects) in signaled conditions. In a final series of signaled conditions with relatively long terminal links, preference varied with duration of the initial links. The results extend previous findings and are discussed in terms of the delay reduction signaled by terminal-link stimuli.

Animals↗
PubMed1992

Dissociation of theories of choice by temporal spacing of choice opportunities.

Rats were trained on a discrete-trial version of a concurrent variable-interval (VI) variable-ratio (VR) schedule in which the relative reinforcement rates were varied across conditions. Subjects with the shorter intertrial interval (ITI) had a significant bias toward the VR alternative, as predicted by optimality theory, and were also more likely to choose the VI alternative with longer times since responses to the VI alternative, as predicted by momentary-maximizing theory. Subjects with the longer ITI failed to show either of these effects. Approximation to the matching law was greater with the longer ITI. Thus, matching is not derivative of the processes postulated by optimality or momentary-maximizing theory but instead is in competition with those processes.

Animals↗
PubMed1990

Rule abstraction, item memory, and chunking in rat serial-pattern tracking.

Two studies used a stimulus tracking paradigm to test whether rats are sensitive to the rule-based formal properties of structured serial patterns. Hooded rats tracked 16-element patterns of flashing lights by pressing levers under an array of 6 indicator lights. In Experiment 1, rats tracked a pattern similar to one previously used with human subjects and yielded remarkably similar results. More errors and response omissions occurred at boundaries of structural "chunks" than within chunks, and errors often reflected anticipation of the next chunk or extrapolation of the preceding chunk. In Experiment 2, temporal "phrasing" cues encouraged different groups to encode a pattern as a series of either "runs" or "trills." Differential placement of pauses induced rats to encode different rule-based representations of the pattern. Results indicate that under appropriate conditions rats may encode a representation of formal structure when they learn organized response patterns.

Animals↗
PubMed1989

Base-rate effects in category learning: a comparison of parallel network and memory storage-retrieval models.

Exemplar-memory and adaptive network models were compared in application to category learning data, with special attention to base rate effects on learning and transfer performance. Subjects classified symptom charts of hypothetical patients into disease categories, with informative feedback on learning trials and with the feedback either given or withheld on test trials that followed each fourth of the learning series. The network model proved notably accurate and uniformly superior to the exemplar model in accounting for the detailed course of learning; both the parallel, interactive aspect of the network model and its particular learning algorithm contribute to this superiority. During learning, subjects' performance reflected both category base rates and feature (symptom) probabilities in a nearly optimal manner, a result predicted by both models, though more accurately by the network model. However, under some test conditions, the data showed substantial base-rate neglect, in agreement with Gluck and Bower (1988b).

Adult↗