Emergence of words : Multisensory precursors of sound-meaning associations in infancy

Sammanfattning: This thesis presents four experimental studies, carried out at the Phonetic laboratory, Stockholm University, on infants’ ability to establish auditory-visual sound-meaning associations as a precursor of early word acquisition. Study I reports on the effect of linguistic variance on infants’ ability (3- to 20-months) to establish sound-meaning associations. The target-words embedded in phrases, based on an artificial language, were presented along with visually displayed puppets. Study II investigates the role of attribute type on infants’ ability (3- to 6-months) to establish sound-meaning associations. Two-word phrases, based on the same artificial language as in Study I, were presented along with visually displayed geometrical objects. The words implicitly referred to the color and shape of the objects. Study III examines infants’ ability (12- to 16-months) to predict phonetic information. The subjects were tested on their ability to associate Swedish whole words and disrupted words to familiar objects. Study IV investigates infants’ ability (6- to 8-months) to detect concurrence and synchrony in speech and non-speech. The infants were exposed to Swedish speech sounds presented with corresponding articulatory events, the sound of hand-clapping presented with synchronized hand-clapping movements, and the sound of hand-clapping presented with synchronized articulatory events. The results picture the subject as sensitive to distributional properties of auditory and visual information (Study I and II) but still unable to predict phonetic information, in the beginning of the second year of life (Study III). The infants’ conceptual behavior is outlined as a general-purpose perceptual process influenced by perceptual salience (Study IV). These results are related to a working hypothesis based on the Ecological theory of language acquisition (Lacerda & Sundberg, 2006), and Lindblom (Lindblom, 1990; Lindblom & Lacerda, 2006).