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Similarity and discrimination learning in humans

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Abstract

In an experiment involving a new behavioural preparation the role played by similarity in discrimination learning was examined using visual patterns (i.e., paintings) that might share common elements (specifically, A, BC, and ABC). A-C were small stars of three specific colours (target colours), which were intermixed with other stars of two different colours (distracting colours). The target colours were balanced through A-C. Students received discrimination training in which a fictitious painter was the author of paintings A and BC, while paintings ABC were assigned to a second fictitious painter. During training, the students had to make a choice, in the presence of each pattern, between two response keys, each of them indicating one of the painters. The time taken to respond was also measured. Feedback was always given after each key-press. The results showed that while at times the A+ ABC- discrimination was acquired more readily than was the BC+ ABC- discrimination, on other occasions the reverse was also true, the critical factor being the way in which the colours were combined.

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A selective review of experiments that can be said to demonstrate the effects of generalization decrement in Pavlovian condition is presented, and it is argued that an adequate theoretical explanation for them is currently not available. This article then develops a theoretical account for the processes of generalization and generalization decrement in Pavlovian conditioning. It assumes that animals represent their environment by a stimulus array in a buffer and that this array in its entirety constitutes the conditioned stimulus. Generalization is then held to occur whenever at least some of the stimuli represented in the array on a test trial are the same as at least some of those represented in the array during training. Specifically, the magnitude of generalization is determined by the proportion of the array occupied by these common stimuli during training compared to the proportion of the array they occupy during testing. By adding to this principle rules concerning excitatory and inhibitory learning, it is proposed, the model can explain all the results that were difficult for its predecessors to account for.
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The 1st part of this article evaluates the extent to which 2 elemental theories of conditioning, stimulus sampling theory and the Rescorla-Wagner (1972) theory, are able to account for the influence of similarity on discrimination learning. A number of findings are reviewed that are inconsistent with predictions derived from these theories, either in their present form or in various modified forms. The 2nd part of the article is concerned with developing an alternative, configural account for discrimination learning. In contrast to previous configural theories, the present version is set within the framework of a connectionist network.
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This paper describes three theoretical approaches to the representation of configural cues in generalization and discrimination in Pavlovian conditioning: that of the Rescorla-Wagner model, the Pearce model, and the authors' 'replaced elements' model. We summarize the results of a generalization experiment using the rabbit Pavlovian conditioned eyeblink response where animals were trained with cues A, AB, or ABC, and tested with A, AB, and ABC. The pattern of generalization decrement in testing supported the replaced elements model.
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We report three Pavlovian eyelid conditioning experiments with humans, designed to experimentally decide between elemental and configural learning theories. We used two different designs originally proposed by Redhead and Pearce (1995). In Experiments 1 and 2, three stimulus elements, A, B, and C, were presented in all possible combinations. All patterns were reinforced except for pattern ABC (A/B/C+, AB/AC/BC+, ABC-). According to elemental learning theories, response proportions on A/B/C+ trials should be smaller than on AB/AC/BC+ trials, whereas configural learning theory makes the opposite prediction. The results confirmed neither prediction. In Experiment 3, the A/B/C+, AB/AC/BC+, and ABC- trials were interspersed by D/E/F-, DE/DF/EF-, DEF+ trials. Again, neither prediction was confirmed. We suggest a modification of configural learning theory as a possible explanation of our results.
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An eyetracking version of the classic Shepard, Hovland, and Jenkins (1961) experiment was conducted. Forty years of research has assumed that category learning often involves learning to selectively attend to only those stimulus dimensions useful for classification. We confirmed that participants learned to allocate their attention optimally. We also found that learners tend to fixate all stimulus dimensions early in learning. This result obtained despite evidence that participants were also testing one-dimensional rules during this period. Finally, the restriction of eye movements to only relevant dimensions tended to occur only after errors were largely (or completely) eliminated. We interpret these findings as consistent with multiple-systems theories of learning which maximize information input in order to maximize the number of learning modules involved, and which focus solely on relevant information only after one module has solved the learning problem.
The Psychology of Colour (Wie Farben auf Gefühl und Verstand wirken)
  • E Heller
Heller, E., 2004. The Psychology of Colour (Wie Farben auf Gefühl und Verstand wirken). Gustavo Gili, Barcelona (Original work published 2000).