On learning to speak.
Every language, spoken or signed, deploys a large lexicon, made possible by permutation and combination of a small set of linguistic elements. In speech, rapid interleaving of the gestures that form these elements (consonants and vowels) leads to a complex acoustic signal in which the boundaries between elements are lost. However, for the child learning to speak, the initial task is not to recover these elements, but simply to imitate the sound pattern that it hears. Studies of "lipreading" in adults and infants suggest that imitation is mediated by an amodal representation, closely related to the dynamics of articulation, and that a left-hemisphere perceptuo-motor mechanism specialized to make use of this representation develops during the first six months of life. By drawing on this specialized mechanism, the infant learns the recurrent patterns of acoustic structure and articulatory gesture from which linguistic segments must be presumed to emerge.
D004292:Dominance, Cerebral; D005149:Facial Expression; D006801:Humans; D007100:Imitative Behavior; D007223:Infant; D007804:Language Development; D010700:Phonetics; D013060:Speech / Q000502:physiology*; D013061:Speech Acoustics; D013067:Speech Perception; D014796:Visual Perception