Nosofsky (1986) modeled identification and categorization performance with highly similar stimuli by using a model involving a "Gaussian" relationship between similarity and Euclidean distance. Nosofsky found that this model fitted his data better than a model involving similarity as an exponential decay function of city-block distance. Nosofsky's stimuli evoked independent perceptual dimensions. Shepard (1986) conjectured that perceptual "noise" may have contributed to the results of Nosofeky's experiments because, in the absence of such noise, previous research suggested that similarity is best modeled as an exponential decay function of city-block distance for stimuli that evoke independent perceptual dimensions. By using a multivariate model of similarity, in which perceptual variation is included, this article provides a possible reconciliation of the kind of result found by Nosofeky (1986) and Shepard's (1986) theory concerning the relationship between similarity and perceptual distance.
This article appears as:
Ennis, D. M. (1988). Confusable and discriminable stimuli: Comments on Nosofsky (1986) and Shepard (1986). Journal of Experimental Psychology: General, 117(4), 408-411.
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Confusable and discriminable stimuli: Comments on Nosofsky (1986) and Shepard (1986)
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