Avian and primate communication: the problem of natural categories

To negotiate effectively with the world on the basis of experience, organisms must classify past events with rules about when to lump stimulus variants into perceptual categories and when to treat them separately. In nature, tactics for evading capture vary with the predator. Appropriately, adult monkey alarm calls are specifically linked to predator category. Linkages are less precise in one-month infants but they discriminate between major predator categories. Associations become more highly specified with experience. Birds discriminate innately between conspecific and alien songs, but vocal perception is subsequently enriched by experience. Monkeys also use special processing in categorizing their own vocal repertoire. In forming perceptual categories birds and monkeys evidently use species-specific predispositions that focus attention on biologically relevant stimuli and ensure commonality in rules used by species members in perceptual analysis. Thus animals are led to share natural perceptual categories to which meaningful communicative labels can be attached.