Interleaving examples of to-be-learned categories, rather than blocking examples by category, frequently enhances category induction. The presently dominant theory is that interleaving promotes discriminative-contrast, and suggests that category similarity structure modulates this interleaving benefit: that blocking should benefit learning when within-category similarity is low and that interleaving should benefit learning when between-category similarity is low. We test whether predictions of this hypothesis hold when generalized to real, complex categories artists' painting styles. Specifically, we test two predictions: (a) that within- and between-category structure should modulate the interleaving benefit (Exp 1a and 1b) and (b) that deliberately juxtaposing similar examples by different artists to highlight their key differences should improve learning (Exp 2a and 2b). We did not, however, find evidence that the discriminative-contrast hypothesis explains the interleaving benefit for complex, perceptual categories.