title: Idealness and similarity in goal-derived categories: a computational examination.
abstract: The finding that the typicality gradient in goal-derived categories is mainly driven by ideals rather than by exemplar similarity has stood uncontested for nearly three decades. Due to the rather rigid earlier implementations of similarity, a key question has remained--that is, whether a more flexible approach to similarity would alter the conclusions. In the present study, we evaluated whether a similarity-based approach that allows for dimensional weighting could account for findings in goal-derived categories. To this end, we compared a computational model of exemplar similarity (the generalized context model; Nosofsky, Journal of Experimental Psychology. General 115:39-57, 1986) and a computational model of ideal representation (the ideal-dimension model; Voorspoels, Vanpaemel, & Storms, Psychonomic Bulletin & Review 18:1006-114, 2011) in their accounts of exemplar typicality in ten goal-derived categories. In terms of both goodness-of-fit and generalizability, we found strong evidence for an ideal approach in nearly all categories. We conclude that focusing on a limited set of features is necessary but not sufficient to account for the observed typicality gradient. A second aspect of ideal representations--that is, that extreme rather than common, central-tendency values drive typicality--seems to be crucial.
authors.affiliation: Department of Psychology, University of Leuven, Tiensestraat 102, 3000 Leuven, Belgium. wouter.voorspoels@psy.kuleuven.be
authors.forename: Wouter
authors.initials: W
authors.lastname: Voorspoels
authors.forename: Gert
authors.initials: G
authors.lastname: Storms
authors.forename: Wolf
authors.initials: W
authors.lastname: Vanpaemel
mesh_terms: D003210:Concept Formation / Q000502:physiology*; D006040:Goals; D006801:Humans; D008960:Models, Psychological