Ideal Is Typical.

A well-established finding in research on concepts and categories is that some members are rated as better or more typical examples than others. It is generally thought that typicality reflects centrality, that is, that typical examples are those that are similar to many other members of the category. This interpretation of typicality is based on studies in which participants had little knowledge about the relevant categories. In the present study, experienced fishermen were asked to give goodness-of-example ratings to familiar freshwater fish. These fishermen were of two cultural groups with somewhat different goals and ideals. Typicality was well predicted by fishes' desirability and poorly predicted by their centrality. Further, the two cultural groups differed in their typicality ratings in ways that corresponded to their different goals and ideals. For knowledgeable reasoners typicality in natural taxonomic categories appears based on ideals rather than on centrality. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Operational thought and the acquisition of taxonomic relations involving figurative dissimilarity.

Atypical exemplars of taxonomic categories (e.g., clothing, furniture) differ from more typical exemplars along figurative dimensions of perceptual and contextual similarity. The advent of operational thought might be expected to facilitate category acquisition because it engenders a competence to suppress figurative dissimilarities and focus on nonfigurative similarities (e.g., common function). Age- and grade-equivalent preoperational and concrete operational groups were given oddity, sort, and category membership tasks with pictorial stimuli. Concrete operational subjects showed a greater appreciation than preoperational subjects for taxonomic relations involving atypical exemplars. Subjects of both cognitive levels could appreciate taxonomic relations involving strictly typical or moderately typical exemplars of a category. Results are interpreted as supporting a contention that meanings become more general with the emergence of operational thought. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Nature of priming effects in semantic matching.

[Correction Notice: An erratum for this article was reported in Vol 12(4) of Journal of Experimental Psychology: Learning, Memory, and Cognition (see record 2008-10970-001). The Appendix table was constructed incorrectly. The correct table appears in the erratum.] Studied priming effects in a semantic matching task that distinguished visually based matching processes from nominally and semantically based matching processes, using 24 undergraduates. Ss judged semantic matches for 3 types of word pairs: identical (e.g., robin–robin), same category (e.g., robin–sparrow), and different category (e.g., robin–truck). Visual matching was isolated by comparing performance between physical identity (e.g., robin–robin) and nominal identity (e.g., robin–ROBIN) pairs. Physical identity pairs, which allowed visually based matching, exhibited an interaction between priming and the typicality of category exemplars that was absent in nominal identity and same-category pairs. Priming had no effect on nominal identity pairs. For same-category pairs, which required semantically based matching, priming produced facilitation at all levels of typicality. The results bring the semantic matching paradigm into agreement with other procedures that show that priming facilitates processing for all related targets. Categories and exemplars used as stimulus materials are appended. (18 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

"Nature of priming effects in semantic matching": Correction to Whitlow.

Reports an error in "Nature of priming effects in semantic matching" by J. W. Whitlow (Journal of Experimental Psychology: Learning, Memory, and Cognition, 1986[Jul], Vol 12[3], 353-360). The Appendix table was constructed incorrectly. The correct table appears in the erratum. (The following abstract of the original article appeared in record 1986-29114-001.) Studied priming effects in a semantic matching task that distinguished visually based matching processes from nominally and semantically based matching processes, using 24 undergraduates. Ss judged semantic matches for 3 types of word pairs: identical (e.g., robin-robin), same category (e.g., robin-sparrow), and different category (e.g., robin-truck). Visual matching was isolated by comparing performance between physical identity (e.g., robin-robin) and nominal identity (e.g., robin-ROBIN) pairs. Physical identity pairs, which allowed visually based matching, exhibited an interaction between priming and the typicality of category exemplars that was absent in nominal identity and same-category pairs. Priming had no effect on nominal identity pairs. For same-category pairs, which required semantically based matching, priming produced facilitation at all levels of typicality. The results bring the semantic matching paradigm into agreement with other procedures that show that priming facilitates processing for all related targets. Categories and exemplars used as stimulus materials are appended. (18 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Similarity, frequency, and category representations.

This article studies the joint roles of similarity and frequency in determining graded category structure. Perceptual classification learning experiments were conducted in which presentation frequencies of individual exemplars were manipulated. The exemplars had varying degrees of similarity to members of the target and contrast categories. Classification accuracy and typicality ratings increased for exemplars presented with high frequency and for members of the target category that were similar to the high-frequency exemplars. Typicality decreased for members of the contrast category that were similar to the high-frequency exemplars. A frequency-sensitive similarity-to-exemplars model provided a good quantitative account of the classification learning and typicality data. The interactive relations among similarity, frequency, and categorization are considered in the General Discussion. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The contribution of category relationships to similarity ratings.

Two experiments with university students produced evidence that category relationships contribute to similarity ratings. In Exp 1, participants gave similarity ratings with respect to a semantic category (VEGETABLE) and a set of exemplars, some of which were members of the category (e.g., BROCCOLI) and some of which were not (e.g., BANANA). A regression analysis was used to predict the similarity ratings in terms of numbers of common and distinctive features, as reported by other participants. Perceived similarity was greater for exemplars that were members of the category, independently of feature overlap. Exp 2 examined similarity ratings with respect to pairs of exemplars. In some cases, both exemplars were members of the same category (e.g., BROCCOLI/CUCUMBER). In other cases, one exemplar was a member of the category and the other was not (e.g., BROCCOLI/BANANA). A regression analysis was used to predict the similarity ratings in terms of numbers of common and distinctive features. Perceived similarity was greater when both exemplars were members of the same category, independently of feature overlap. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Facial expressions of emotion: Does the prototype represent central tendency, frequency of instantiation, or an ideal?

Examines whether typicality of facial expressions (FE) of emotion is predicted best by their values on an ideal dimension (suitability to express a particular emotion), their frequency of instantiation (FI) as an expression of a particular emotion, or their deviation from the central tendency (CT) of the respective FE category. The subjects (Ss) judged FE line drawings of anger, disgust, happiness, sadness, and surprise differing in intensity. In study 1, 82 Ss (mean age 24.4 yrs) divided into four independent groups were tested: the typicality group, the FI group, the ideal group, and the CT group. The Ss in Study 2 (mean age 23.5 yrs) sought to replicate Study 1 with a different operation of typicality: "how good an example" an FE is for the respective emotion category. The results strongly indicate that they are structured like goal-derived categories, where typicality of members varies according to their suitability to obtain a certain goal. This indicates that suitability to express the respective emotion is highly salient in people's representations of categories of FEs of emotion and has become the standard by which typicality is judged. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Role of atypical exemplars of social and nonsocial superordinate categories within the class inclusion paradigm.

Investigated hierarchical categorization using typical and atypical exemplars from social and nonsocial superordinate categories within the class inclusion paradigm. Ss were 96 male and female children in kindergarten and Grades 2, 4, and 6. Of the 33 stimulus pictures, 9 depicted nonsocial categories (e.g., birds), 18 depicted social occupations more typical of males than females (e.g., doctors), and 6 depicted social roles equally typical of males and females (e.g., parents). Results confirm the findings of M. T. Carson and A. Abrahamson (see record 1977-20805-001) that atypical instances of nonsocial categories significantly reduced inclusion performance. A parallel adverse effect was found for atypical exemplars of the social categories with Ss in the midstage of acquisition. Consistent with E. Rosch's (1973) theoretical framework and the findings of Rosch and C. B. Mervis (see record 1976-06117-001), these results are interpreted to reflect differences in the conceptual breadth of children's hierarchical knowledge structures. (23 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Category knowledge in Alzheimer's disease: Normal organization and a general retrieval deficit.

Three hypotheses that could account for deficits in the retrieval of category information in Alzheimer's disease (AD) were evaluated: abnormal organization, class- or category-specific vulnerability, and limitation by general factors, such as decreased processing speed. Relative to 18 elderly control Ss, 18 patients with AD produced fewer items in a category fluency task and had longer reaction times in a category decision task. The pattern of performance across categories on both tasks was normal in the AD group: The same categories elicited the most (or fastest) responses in both the control group and the AD group. AD patients showed normal performance in ranking of category exemplars by typicality. There was no evidence for differential accessibility by category or by class of information (animate vs inanimate). The authors conclude that a general factor or factors limit(s) retrievability equally across all categories. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Distinguishing prototype-based and exemplar-based processes in dot-pattern category learning.

The authors contrast exemplar-based and prototype-based processes in dot-pattern categorization. In Experiments 1A and 1B, participants provided similarity ratings of dot-distortion pairs that were distortions of the same originating prototype. The results show that comparisons to training exemplars surrounding the prototype create flat typicality gradients within a category and small prototype-enhancement effects, whereas comparisons to a prototype center create steep typicality gradients within a category and large prototype-enhancement effects. Thus, prototype and exemplar theories make different predictions regarding common versions of the dot-distortion task. Experiment 2 tested these different predictions by having participants learn dot-pattern categories. The steep typicality gradients, the large prototype effects, and the superior fit of prototype models suggest that participants refer to-be-categorized items to a representation near the category's center (the prototype), and not to the training exemplars that surround the prototype. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Inferring category attributes from exemplar attributes: Geometric shapes and social categories.

Three experiments tested the hypothesis that judgments about the attributes of categories are disproportionately based on the characteristics of exemplars that fit the category. In the first 2 experiments, subjects were presented with good and bad exemplars of categories with defining attributes (rectangles, triangles, pentagons, and ellipses) in which different colors were arbitrarily paired with the good and poor exemplars. In both experiments, subjects erroneously judged the colors paired with the good exemplars as more frequent than colors paired with the poor exemplars. A third experiment, using social categories, examined whether attributes associated with a single category member were more likely to generalize to the category as a whole for prototypical than for nonprototypical category members. Subjects were presented with information about individual fraternity members who varied in prototypicality, and the tendency to infer a target behavior (liberal vs. conservative voting behavior) from the individual fraternity member to the fraternity as a whole increased with the prototypicality of the category member. Implications for the contact hypothesis, category–exemplar relations, and belief stability are discussed. (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

Relational similarity and context effects in category verification.

Two experiments with a total of 50 undergraduate and graduate students measured the effects of coordinate falses, which pair 2 exemplars from a common category (e.g., "A dog is a cat"), on latencies to true items in a category verification task. Results show that although, relative to anomalous falses, coordinate falses did not increase latencies to trues, the size of the increase did not vary with the similarity of the coordinates. Furthermore, latencies were faster to coordinate falses that were more similar than to coordinate falses that were less similar. These results suggest relational similarity is as powerful a predictor of performance in category verification as is attribute similarity. Finally, there was some evidence that the increase in latencies was the same for typical and atypical category exemplars. It is concluded that this last finding, if substantiated, indicates that relational information is generally accessed prior to attribute information. (30 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Journey to the center of the category: The dissociation in amnesia between categorization and recognition.

The authors' theoretical analysis of the dissociation in amnesia between categorization and recognition suggests these conclusions: (a) Comparing to-be-categorized items to a category center or prototype produces strong prototype advantages and steep typicality gradients, whereas comparing to-be, categorized items to the training exemplars that surround the prototype produces weak prototype advantages and flat typicality gradients; (b) participants often show the former pattern, suggesting their use of prototypes; (c) exemplar models account poorly for these categorization data, but prototype models account well for them; and (d) the recognition data suggest that controls use a single-comparison exemplar-memorization process more powerfully than amnesics. By pairing categorization based in prototypes with recognition based in exemplar memorization, the authors support and extend other recent accounts of cognitive performance that intermix prototypes and exemplars, and the authors reinforce traditional interpretations of the categorization-recognition dissociation in amnesia. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Retrieval from semantic memory and its implications for Alzheimer's disease.

In 3 experiments, participants generated category exemplars (e.g., kinds of fruits) while a voice key and computer recorded each response latency relative to the onset of responding. In Experiment 1, mean response latency was faster when participants generated exemplars from smaller categories, suggesting that smaller mental search sets result in faster mean latencies. In Experiment 2, a concurrent secondary task increased mean response latency, suggesting that slowed mental processing results in slower mean latencies. In Experiment 3, the mean response latency of Alzheimer's participants was faster than that of elderly controls, which is consistent with the idea that the semantic memory impairments of Alzheimer's disease patients stem primarily from a reduction in available items (as in Experiment 1) rather than retrieval slowing (as in Experiment 2). (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Storage and retrieval of associative clusters: A stages-of-learning analysis of associative memory traces.

In this research, the assumptions underlying the unitary trace theory of item representation and acquisition were tested in two cued-recall experiments in which the degree of preexperimental knowledge (typicality) was manipulated. Subjects learned lists of word triads (each of which consisted of a single cue and two targets) to a stringent acquisition criterion. In Experiment 1, typicality was manipulated in the absence of semantic relationships between members of the associative clusters. In Experiment 2, semantic relationships were present among cluster members, and preexperimental knowledge was manipulated by varying the degree of intracluster category membership as measured by whether cue and target items were typical or atypical category exemplars. In both experiments a mathematical model that embodies stages-of-learning distinctions was used to analyze the acquisition data. The results indicated that (1) cues and targets were represented in a single holistic memory trace, and (2) the manipulation of the degree of preexperimental knowledge affected both trace storage and retrieval learning, but had only a minimal impact on retrieval performance between the time a trace was stored and the time retrieval learning was complete. It was argued that these findings are consistent with a single unitary trace interpretation, namely, the modified storage-retrieval model. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

By land or by sea: The role of perceptual similarity in infants' categorization of animals.

In 3 experiments, the authors used an object-examining task to investigate the role of perceptual similarity in infants' categorization. In Experiment 1, infants were familiarized with a set of either perceptually similar or perceptually variable exemplars from 1 category and tested with novel exemplars from both categories. Ten-month-olds did not respond to the category in either condition, and 13-month-olds responded categorically in both conditions but somewhat differently in the 2 conditions. Experiment 2 showed that when 10-month-olds were familiarized with similar exemplars but not with variable exemplars, they responded to the categorical distinction when given tests with typical exemplars. Experiment 3 established that 10-month-olds could differentiate among the exemplars. These results suggest that the perceptual similarity of the exemplars influences infants' recognition of categorical distinctions. (PsycINFO Database Record (c) 2010 APA, all rights reserved)