unequal scale steps), which means that musical experience tends to intensify the initial biases
or predispositions.
Temporal processing
Similar adult–infant parallels are observable in the temporal domain (see Drake and
Bertrand, Chapter 2, this volume). For example, infants differentiate tone sequences with
identical pitches but contrasting rhythmic arrangements.31,45,91They also impose rhythmic
groupings on isochronous tone sequences on the basis of pitch or timbre similarities.42,43
The temporal organization of a sequence also has implications for infants’processing of
pitch and timing details.^92 For example, melodic processing is enhanced when tone dura-
tions are related by binary ratios,93,94as is the case for children and adults.^95 –^97 Te m p o r a l
processing predispositions (Drake and Bertand, Chapter 2, this volume) may account for
the fact that adults’preferred rhythmic arrangements of melodies generate better infant
performance than do non-preferred arrangements.^94 They may also account for superior
infant performance on patterns with regular rather than syncopated rhythms.^93
Hemispheric specialization
Well before infants understand language, they show a right-ear (i.e. left hemisphere)
advantage for speech and a left-ear (i.e. right hemisphere) advantage for music.98,99
Moreover, 8-month-old infants exhibit a left-ear superiority for contour processing and a
right-ear superiority for interval processing.^100 Such laterality effects parallel those reported
for adults101,102(but see Zatorre, Chapter 16, this volume).
Maternal music
The relevance of these processing predispositions to the daily lives of infants is unclear.
Typical laboratory studies use musical stimuli (e.g. sequences of pure tones) that differ
dramatically from the music that infants experience. Caregivers across cultures produce
distinctive, solo performances of songs for infant listeners.12,103–^105 They also speak to
infants in a sing-song manner that incorporates a number of musical features.52,106,107For
example, mothers’speech differs from women’s usual speech (e.g. pitch level, pitch
contours, tempo, rhythm) in ways that reflect its greater emotional expressiveness.52,55,108
Infants prefer this maternal speaking style to the usual adult style.^109 –^111
When caregivers sing to infants, they generally use a special-purpose repertoire consist-
ing of lullabies and play songs.12,104To the naïve adult listener, the tunes of unfamiliar lul-
labies, including those from foreign musical cultures, sound much like those of familiar
lullabies. In fact, adults successfully identify unfamiliar lullabies from pairs of novel lulla-
bies and nonlullabies matched on culture of origin and tempo.^112 Adults also perceive for-
eign lullabies as simpler and more repetitive than nonlullabies.^113
Among the performance alterations that distinguish singing to infants from other
singing are raised pitch level, decreased tempo, and an emotive voice quality.^114 –^116 In
addition, mothers’song renditions are tailored to the age and needs of the listener. For
example, maternal singing is approximately one-semitone higher in pitch level for infant
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