Infants' sensitivity to vowel and tonal contrasts.

McGill UniversityInfants 4 to 17 weeks of age were presented with sound which was con-tingent upon nonnutritive sucking. When the infants gave evidence ofsatiation to the initial stimulus, a contrasting sound was substituted. Sig-nificant response recovery was found when the stimuli were vowel con-trasts but was absent when the stimuli were tones differing in frequency.