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. Author manuscript; available in PMC: 2011 Apr 1.
Published in final edited form as: Psychol Rev. 2010 Apr;117(2):309–348. doi: 10.1037/a0018526

Figure 1.

Figure 1

Left Panel: Schematic illustration of the structure of the stimulus set used for introducing and testing the logical-rule models of classification. The stimuli are composed of two dimensions, X and Y, with three values per dimension, combined orthogonally to produce the nine members of the stimulus set. The stimuli in the upper-right quadrant of the space (x1y1, x1y2, x2y1, and x2y2) are the members of the “target” category (Category A), whereas the remaining stimuli are the members of the “contrast” category (Category B). Membership in the target category is described in terms of a conjunctive rule, and membership in the contrast category is described in terms of a disjunctive rule. The dotted boundaries illustrate the decision boundaries for implementing these rules. Right Panel: Shorthand nomenclature for identifying the main stimulus types in the category structure.