title: Visual speech contributes to phonetic learning in 6-month-old infants.
abstract: Previous research has shown that infants match vowel sounds to facial displays of vowel articulation [Kuhl, P. K., & Meltzoff, A. N. (1982). The bimodal perception of speech in infancy. Science, 218, 1138-1141; Patterson, M. L., & Werker, J. F. (1999). Matching phonetic information in lips and voice is robust in 4.5-month-old infants. Infant Behaviour & Development, 22, 237-247], and integrate seen and heard speech sounds [Rosenblum, L. D., Schmuckler, M. A., & Johnson, J. A. (1997). The McGurk effect in infants. Perception & Psychophysics, 59, 347-357; Burnham, D., & Dodd, B. (2004). Auditory-visual speech integration by prelinguistic infants: Perception of an emergent consonant in the McGurk effect. Developmental Psychobiology, 45, 204-220]. However, the role of visual speech in language development remains unknown. Our aim was to determine whether seen articulations enhance phoneme discrimination, thereby playing a role in phonetic category learning. We exposed 6-month-old infants to speech sounds from a restricted range of a continuum between /ba/ and /da/, following a unimodal frequency distribution. Synchronously with these speech sounds, one group of infants (the two-category group) saw a visual articulation of a canonical /ba/ or /da/, with the two alternative visual articulations, /ba/ and /da/, being presented according to whether the auditory token was on the /ba/ or /da/ side of the midpoint of the continuum. Infants in a second (one-category) group were presented with the same unimodal distribution of speech sounds, but every token for any particular infant was always paired with the same syllable, either a visual /ba/ or a visual /da/. A stimulus-alternation preference procedure following the exposure revealed that infants in the former, and not in the latter, group discriminated the /ba/-/da/ contrast. These results not only show that visual information about speech articulation enhances phoneme discrimination, but also that it may contribute to the learning of phoneme boundaries in infancy.
authors.affiliation: Department of Psychology, University of Helsinki, Helsinki, Finland. tuomas.teinonen@helsinki.fi
authors.forename: Tuomas
authors.initials: T
authors.lastname: Teinonen
authors.forename: Richard N
authors.initials: RN
authors.lastname: Aslin
authors.forename: Paavo
authors.initials: P
authors.lastname: Alku
authors.forename: Gergely
authors.initials: G
authors.lastname: Csibra
mesh_terms: D001288:Attention; D003463:Cues; D005260:Female; D006801:Humans; D007223:Infant; D007804:Language Development; D008085:Lipreading; D008297:Male; D010700:Phonetics; D013067:Speech Perception