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Recent research in relational learning has suggested that simple training instances may lead to better generalization than complex training instances. We examined the perceptual-encoding mechanisms that might undergird this "simple advantage" by testing category and perceptual learning in adults with simplified and traditional (more complex) Chinese scripts. In Experiment 1, participants learned Chinese characters and their English translations, performed a memorization test, and generalized their learning to the corresponding characters written in the other script. In Experiment 2, we removed the training phase and modified the tests to examine transfer based purely on the perceptual similarities between simplified and traditional characters. We found the simple advantage in both experiments. Training with simplified characters produced better generalization than training with traditional characters when generalization relied on either recognition memory or pure perceptual similarities. On the basis of the results of these two experiments, we propose a simple process model to explain the perceptual mechanism that might drive this simple advantage, and in Experiment 3 we tested novel predictions of this model by examining the effect of exposure duration on the simple advantage. We found support for our model that the simple advantage is driven primarily by differences in the perceptual encoding of the information available from simple and complex instances. These findings advance our understanding of how the perceptual features of a learning opportunity interact with domain-general mechanisms to prepare learners for transfer.

In two experiments, we examined the representation, treatment, and attention devoted to the members of reference (i.e., club members) and nonreference (i.e., not club members) categories. Consistent with prior work on category interrelatedness (e.g., Goldstone, 1996; Goldstone, Steyvers, and Rogosky, 2003), the findings reveal the existence of asymmetric representations for reference and nonreference categories, which, however, decreased as expertise and familiarity with the categories increased (Experiments 1 and 2). Participants also more readily judged two reference exemplars as being the same than they did two nonreference exemplars (Experiment 1) and were better at detecting reference than nonreference exemplars in a set of novel, category-unspecified exemplars (Experiment 2). These findings provide evidence for the existence of a feature asymmetry in the representation and treatment of exemplars from reference and nonreference categories. Membership in a reference category acts as a salient feature, thereby increasing the perceived similarity and detection of faces that belong in the reference, in comparison with the nonreference, category.

Participants categorized left- and right-pointing line drawings presented together with pictures, whose pointing direction (to the left or right) was ambiguous (spatially ambiguous pictures; Experiments 1 and 2) or that pointed neither to the left nor to the right (spatially neutral pictures; Experiment 3). Subsequently, the spatially ambiguous and neutral pictures were used in a Simon task, wherein participants made left and right keypresses on the basis of the color of the pictures, while ignoring the object that they depicted. In all three experiments, performance was facilitated when the response required by the color matched the pointing direction of the line drawings with which the picture had been previously paired. Performance was impeded when the response required by the color did not match the pointing direction of the line drawings with which the picture had been previously paired. Thus, responses indirectly associated with pictures by category membership were automatically triggered even when the responses were inappropriate.

Similarity comparisons are highly sensitive to judgment context. Three experiments explore context effects that occur within a single comparison rather than across several trials. Experiment 1 shows reliable intransitivities in which a target is judged to be more similar to stimulus A than to stimulus B, more similar to B than to stimulus C, and more similar to C than to A. Experiment 2 explores the locus of Tversky's (1977) diagnosticity effect in which the relative similarity of two alternatives to a target is influenced by a third alternative. Experiment 3 demonstrates a new violation of choice independence which is explained by object dimensions' becoming foregrounded or backgrounded, depending upon the set of displayed objects. The observed violations of common assumptions to many models of similarity and choice can be accommodated in terms of a dynamic property-weighting process based on the variability and diagnosticity of dimensions.

A continuum between purely isolated and purely interrelated concepts is described. Along this continuum, a concept is interrelated to the extent that it is influenced by other concepts. Methods for manipulating and identifying a concept's degree of interrelatedness are introduced. Relatively isolated concepts can be empirically identified by a relatively large use of nondiagnostic features, and by better categorization performance for a concept's prototype than for a caricature of the concept. Relatively interrelated concepts can be identified by minimal use of nondiagnostic features, and by better categorization performance for a caricature than for a prototype. A concept is likely to be relatively isolated when subjects are instructed to create images for their concepts rather than find discriminating features, when concepts are given unrelated labels, and when the categories that are displayed alternate rarely between trials. The entire set of manipulations and measurements supports a graded distinction between isolated and interrelated concepts. The distinction is applied to current models of category learning, and a connectionist framework for interpreting the empirical results is presented.