Toward a Unified Theory of Similarity and Recognition

F. Gregory Ashby, Nancy A. Perrin

Research output: Contribution to journalArticlepeer-review

252 Scopus citations


A new theory of similarity, rooted in the detection and recognition literatures, is developed. The general recognition theory assumes that the perceptual effect of a stimulus is random but that on any single trial it can be represented as a point in a multidimensional space. Similarity is a function of the overlap of perceptual distributions. It is shown that the general recognition theory contains Euclidean distance models of similarity as a special case but that unlike them, it is not constrained by any distance axioms. Three experiments are reported that test the empirical validity of the theory. In these experiments the general recognition theory accounts for similarity data as well as the currently popular similarity theories do, and it accounts for identification data as well as the long-standing "champion" identification model does.

Original languageEnglish (US)
Pages (from-to)124-150
Number of pages27
JournalPsychological Review
Issue number1
StatePublished - Jan 1988
Externally publishedYes

ASJC Scopus subject areas

  • Psychology(all)


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