I hypothesized that stickleback that eat benthic prey should have better spatial cognition than planktivores because the location of plankton is highly unpredictable and planktivores should have less use for spatial cognition. Peter Park’s preliminary data indicate that there are differences in the structure of the threespine stickleback brain in the area implicated in spatial cognition, and that individuals from benthic-feeding populations learn to solve mazes more efficiently than planktivores do.