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Foundation Grant BNS-80-22760 and by a Biomedical view a sequence of slides depicting an event Research Support Grant. We thank Howard Egeth and such as a traffic accident. The subjects then Gary Hatfleld for their helpful comments, Robert Chrisreceive additiona l information about the tiaansen for providing information about the Chnsfiaansen . ... ,. ± c and Ochalek (1983) study, David Lim for testing subjects, event > such as a ^M m narrative account of and Margaret Meng and Pat Nguyen for help in preparing what took place. For subjects m the misled the slide sequence. We especially thank Judy McKenna condition, the narrative provides misleading for her insightful criticisms and helpful suggestions re-i n f orma ti on about a detail from the slide •^SZTZr^^fit sent to Michae, *

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University students were asked to draw the path a moving object would follow in several different situations. Over half of the students, including many who had taken physics courses, evidenced striking misconceptions about the motion of objects. In particular, many students believed that even in the absence of external forces, objects would move in curved paths.

Thirty college students made category membership decisions for each of 540 candidate exemplar-category name pairs (e.g., apple-fruit) in each of two separate sessions. For highly typical category members (e.g., chair for the furniture category), and for items unrelated to a category (e.g., cucumber-furniture), subjects agreed with each other and were consistent in their decisions. However, for intermediate-typicality items (e.g., bookends-furniture), subjects disagreed with each other and were frequently inconsistent from one session to the next. These data suggest that natural categories are fuzzy sets, with no clear boundaries separating category members from nonmembers.

The sensory input that we experience is highly patterned, and we are experts at detecting these regularities. Although the extraction of such regularities, or statistical learning (SL), is typically viewed as a cortical process, recent studies have implicated the medial temporal lobe (MTL), including the hippocampus. These studies have employed fMRI, leaving open the possibility that the MTL is involved but not necessary for SL. Here, we examined this issue in a case study of LSJ, a patient with complete bilateral hippocampal loss and broader MTL damage. In Experiments 1 and 2, LSJ and matched control participants were passively exposed to a continuous sequence of shapes, syllables, scenes, or tones containing temporal regularities in the co-occurrence of items. In a subsequent test phase, the control groups exhibited reliable SL in all conditions, successfully discriminating regularities from recombinations of the same items into novel foil sequences. LSJ, however, exhibited no SL, failing to discriminate regularities from foils. Experiment 3 ruled out more general explanations for this failure, such as inattention during exposure or difficulty following test instructions, by showing that LSJ could discriminate which individual items had been exposed. These findings provide converging support for the importance of the MTL in extracting temporal regularities.