Lateral asymmetries in infant melody perception

Two experiments investigated lateral asymmetries n infants ' perception f contour-altered and con-tour-preserved melody changes. In the first study, 40 infants (8.5 months old) of right-handed parents were trained to respond to binaural melody changes with a head turn toward mechanized toy reinforcers. The subsequent test phase included monaural left-ear and right-ear presentations of the familiar melody and of a changed melody. Infants who heard a contour-altered change showed a left-ear advantage, whereas infants who heard a contour-preserved change showed a right-ear advantage. These effects were replicated with a different set of melodies in the second study. The pattern of lateralization fordetection ofmelody changes ininfants of right-handed parents resembles that previously found in right-handed a ults and may reflect more general hemispheric processing differences inthe early organization f auditory information processing. Lateral asymmetries in perception exist across modalities and across species and often reflect specialization of processing in the cerebral hemispheres ( ee Hellige, 1993, for a review). Ini-tial characterizations of broad distinctions between hemispheres have been supplanted by the notion that more precise definition