Table 1.

Category mean, variance, and covariance parameters

Category Structure	μ A	μ B	σ 2 o	σ 2 f	cov o,f
II	40, 60	60, 40	175	175	103
RB	35.9, 50	65.1, 50	72	278	0

Mean, variance, and covariance parameters of the bivariate normal distributions used to generate stimuli for the II and RB categories; o denotes orientation and f denotes spatial frequency. Means are (o, f) coordinate pairs; variances and covariances are equal for the A and B categories in both category structures. All values reported are prior to orientation and spatial frequency transformations.