title: Operant acquisition of social behaviors in infancy: basic problems and constraints.
mesh_terms: D003216:Conditioning, Operant; D005246:Feedback; D006185:Habituation, Psychophysiologic; D006801:Humans; D007223:Infant; D012056:Reinforcement, Social; D012904:Smiling; D012919:Social Behavior; D014705:Verbal Behavior