Contingencies governing the production of fricatives, affricates, and liquids in babbling

Studies of early-developing consonants (stops, nasals, and glides) in babbling have shown that most of the variance in consonants and their associated vowels, both within and between syllables, is due to a "frame" produced by mandibular oscillation, with very little active contribution from intrasyllabic or intersyllabic tongue movements. In a study of four babbling infants, the prediction that this apparently basic "frame dominance" would also apply to late-developing consonants (fricatives, affricates, and liquids) was tested. With minor exceptions, confirming evidence for both the predicted intrasyllabic and intersyllabic patterns was obtained. Results provide further evidence for the frame dominance conception, but suggest that the early rarity of late-developing consonants may be primarily a result of intrasegmental production difficulty.