Summary: Journal of ExperimentalPsychology: Copyright 1990by the AmericanPsychologicalAssociation,Inc.
Human Perception and Performance 0096-1523/90/$00.75
1990,Vol. 16, No. 3, 598-612
Integrating Information From Separable Psychological Dimensions
F. Gregory Ashby and W. Todd Maddox
University of California, Santa Barbara
This article examines decision processesin the perception and categorization ofstimuli composed
of the separable psychological dimensions, orientation and size. The randomization technique
(Ashby & Gott, 1988) of general recognition theory, which allows accurate estimation of a
subject's decision boundary in a categorization task, is used in 4 experiments. Even though the
stimulus components are clearly separable, it was found that Ss were not constrained to use
separable response strategies, nor were they constrained to attend to distance to the prototypes.
Instead, they used decision rules that were nearly optimal, even if this required information
integration or for the Ss to attend to higher level category properties such as component
A fundamentally important problem is to determine how
stimulus dimensions are combined in perceptual processing.
Although a variety of perceptual interactions have been pro-
posed (Ashby & Townsend, 1986; Garner & Morton, 1969),
it is especially popular to characterize perceptual dimensions