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ELEANOR ROSCH
While Experiment 3 has indicated that the effects of the internal structure of categories on priming cannot be dismissed as an artifact of the fact that poor examples of categories are actually members of other categories, it is undeniable that the poor examples of the categories used in the present research were "closer" to other categories than were the good examples. However, this was not due to an artifactual choice of particular items; rather, it is a necessary aspect of the structure of real world categories. That is, categories appear to form in the real world in a manner which renders them maximally discriminate from each other, and, thus, the best examples of categories are those items both with the most attributes in common with other members of the category in question and with the least attributes in common with, or least possibility of membership in, other categories; such facts have been demonstrated for both natural and artificial categories (Rosch & Mervis, in press; Rosch, Mervis, Gray, Johnson, & Boyes-Braem, in press; Rosch, Simpson, & Miller, Note 1). These facts are some of the structural bases which may lie behind the norms of Experiment 1 ; the purpose of the present research, however, was not to investigate the formation of categories but to examine the nature (i.e., the structure and content) of the cognitive representation of the category (as it is generated from hearing the category name). What appears to be the case is that the natural structure of categories (which is quite different from a list of attributes necessary and sufficient for category membership) is represented in the cognitive representation of the category. Experiment 3 has clarified one aspect of the meaning of the results of Experiment 2 ; namely, it has shown that the results of Experiment 2 were not an artifact of the use of poor example items which were actually members of categories not named by the prime. However, there remains a second aspect of Experiment 2 for which comparison data must be obtained before the results of Experiment 2 can be interpreted. According to the logic of priming outlined in the introduction, interpretation of the results
of priming with a 2-sec delay (the condition of Experiment 2) can only be made when compared to results obtained when the prime is administered simultaneously with the stimulus. Experiment 4 was designed to provide the necessary comparison. EXPERIMENT 4 In Experiment 2, priming selectively facilitated and impeded responses to good and poor examples of categories for physically identical pairs, and it had a constant facilitatory effect on same-category and different pairs, regardless of level of goodness of example. Any of these outcomes, however, could as well have been the result of effects on decision processes after the stimuli were presented as the result of generation of a representation of the category prior to presentation of the stimuli. The present experiment was designed to test the locus of the facilitation effect by simultaneous presentation of the prime and the stimulus pair. Priming effects which are the result of generation of a representation prior to viewing the pair should disappear if the prime and the visual stimulus are presented simultaneously. On the other hand, priming effects which are at least partly the result of decision time after the pair is present should still occur when the prime and visual stimulus are presented simultaneously. Method Subjects Subjects were 20 native English-speaking students in introductory psychology classes who had not participated in the previous experiments. They received course credit for their participation.
Because in the previous experiments, effects of Set 1 had been shown not to differ from those of Set 2 (or Set 3), it appeared justifiable to use only the Set 1 stimuli in the present experiment.
Procedure With two exceptions, procedures were identical to those in Experiment 2. In the present experiment, instead of a 2-sec interval between the prime or blank and presentation of the stimulus pair, the pair of stimuli were presented to the subject simultaneously with the experimenter's