Associative and similarity-based processes in categorization decisions

Abstract

Two experiments were directed at distinguishing associative and similarity-based accounts of systematic differences in categorization time for different items in natural categories. Experiment 1 investigated the correlation of categorization time with three measures of instance centrality in a category. Production frequency (PF), rated typicality, and familiarity from category norms for British participants (Hampton & Gardiner, 1983) were used to predict mean categorization times for 531words in 12 semantic categories. PF and typicality (but not familiarity) were found to make significant and independent contributions to categorization time. Error rates were related only to typicality (apart from errors made to ambiguous or unknown items). Experiment 2 provided a further dissociation of PF and typicality. Manipulating the difficulty of the task through the relatedness of the false items interacted primarily with the effect of typicality on categorization time, whereas, under conditions of easy discrimination, prior exposure to the category exemplars affected only the contribution of PF to the decision time. The dissociation of typicality and PF measures is interpreted as providing evidence that speeded categorization involves both retrieval of associations indexed by PF and a similarity-based decision process indexed by typicality.The phenomenon of gradedness within categories is the finding that some instances of common taxonomic categories (e.g., robin as a bird) are consistently judged as more typical or representative of their categories than are others (Barsalou, 1985;Hampton, 1979;Rosch, 1975). Typical instances have been shown to receive preferential processing in a wide range of cognitive tasks (for a review, see Hampton, 1993). For example, in a speeded categorization task, typical words are categorized more rapidly and more accurately than are atypical words (Hampton, 1979;Smith, Shoben, & Rips, 1974). Typical instances also tend to be generated with a high production frequency when people are asked to retrieve examples of categories from memory (Battig & Montague, 1969;Hampton & Gardiner, 1983;Mervis, Catlin, & Rosch, 1976).There are two fundamentally different ways of interpreting gradedness effects in common taxonomic categories. One is in terms of the learning history of the individual, and it proposes that "good" category members are those that have been most often associated with the category in the past. For example, nonanalytic models of category learning and concept representation (e.g., Brooks, 1978Brooks, , 1987 would emphasize the importance of past associations in determining speed of categorization. The other interpretation is in terms of what Rosch (1975) The author thanks Larry Barsalou, John Gardiner, Margaret Gardiner, David Green, Frank Keil, Robert Lorch, Michael McCloskey, and anonymous reviewers for comments and suggestions on the research, and Andy Ojukwu and Bill Fitzpatrick for assistance in data collection. Correspondence should be addressed to the author at the Psychology De...

Word associations: Norms for 1,424 Dutch words in a continuous task

“…In the context of semantic categorization research, the relationship between instances and the category are often described in terms of exemplar and category strength or dominance (e.g., Casey, 1992; Hampton, 1997;Larochelle et al, 2000;Ward et al, 2002). Controlled associations tasks to estimate these variables show strong agreement with the gradedness or exemplar/category strength measures obtained in a free continuous association task.…”

“…The results shown above seem to confirm this. This finding opens up an additional use of the association norms as estimates of gradedness in a category instantiated by what is also called exemplar strength in the categorization literature (e.g., Casey, 1992;Hampton, 1997;Larochelle, Richard, & Soulieres, 2000;Ward, Patterson, Sifonis, Dodds, & Saunders, 2002). The reverse measure, category strength, is an associative measure of strength between an exemplar and a superordinate category.…”

When intensions do not map onto extensions: Individual differences in conceptualization.

“…Robins were very reliably considered by U.S. students to be more typical birds than were ostriches or penguins. Aggregated group data for typicality, category membership, and other measures of conceptual representation have also proved to be reliable predictors of performance at the individual level in many other cognitive tasks (Hampton, 1997;Murphy, 2002).…”

Impact of varying levels of expertise on decisions of category typicality

“…Thus, individuals with varying levels of domain-specific knowledge should persist in rating as highly typical those instances that are most similar to other instances in terms of overall shape or shared features. Hampton (1997) demonstrated through a speeded categorization task that semantic memory is influenced by both associationist and similarity-based comparison processes, and he argued that integrating these two approaches into a common representational system is an important challenge for the field. It also seems critical that the role of expert knowledge be considered in the refinement of models of semantic memory, particularly given the current dominance of the concepts-in-theories view (Keil, 1994;Medin, 1989;Murphy, 1993;Murphy & Medin, 1985).…”

“…The domain of passerine birds (small birds that perch and generally sing) was selected as the focus of study because of its taxonomic depth and the availability of individuals with relatively high levels of relevant knowledge. Hampton (1997) reviewed two competing theoretical frameworks that have been recruited to account for typicality effects in models of semantic memory. First, the associationist approach is based on principles of associative learning and emphasizes the learning history of This research was supported by NIMH Grant MH53134 to K.E.J.…”