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Normal subjects are better at identifying and remembering concrete as compared to abstract words (the concreteness effect). We present data on a patient, DM, who shows the opposite pattern. DM has a progressive semantic loss due to atrophic changes in his temporal lobes, particularly on the left. His semantic impairment predominantly involves object terms, with relative sparing of abstract nouns and most aspects of verb meaning. DM showed an advantage for abstract words on a wide range of tasks (e.g. producing definitions, synonymy judgments). These data challenge accounts that attribute the concreteness effect to a quantitative superiority at the level of the underlying conceptual representations. We suggest that there are qualitative differences between abstract and concrete concepts, and that, in particular, concrete concepts are more dependent on perceptual attributes that were disproportionately impaired in DM. We propose, further, that perceptual components of semantic representations are associated with structures in the inferior temporal lobe(s).

People often make erroneous predictions about the trajectories of moving objects. McCloskey (1983a, 1983b) and others have suggested that many of these errors stem from well-developed, but naive, theories of motion. The studies presented here examine the role of naive impetus theory in people's judgments of motion. Subjects with and without formal physics experience were asked to draw or select from alternatives the trajectories of moving objects that were presented in various manners. Results from two experiments indicate that both trajectory judgments and explanations were affected by specific response and display features of the problem. In addition, these data provide little evidence that naive impetus theory plays a significant role in subjects' performance; instead, they suggest that motion judgments and explanations are constructed on the fly from contextual cues and knowledge that is not necessarily naive.

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