Stimuli and the texture of experience.
Evidence from human language learning and stimulus control of learned and unlearned behavior suggests that generalization and categorization are based on principles of similarity that have evolved to favor the perception of recurrent events and extended objects. The perceptual similarities are typically more complex than, and only occasionally approximated by, physical similarity. In some, but not all, cases, perceptual similarity is tantamount to innate knowledge.
D000818:Animals; D001519:Behavior; D001527:Behaviorism; D010856:Columbidae; D003210:Concept Formation; D003213:Conditioning, Psychological; D004192:Discrimination, Psychological; D005010:Ethology; D005793:Generalization, Psychological; D006801:Humans; D007804:Language Development; D010465:Perception; D013060:Speech; D014796:Visual Perception