Auditory-visual speech perception in three- and four-year-olds and its relationship to perceptual attunement and receptive vocabulary.

Despite the body of research on auditory-visual speech perception in infants and schoolchildren, development in the early childhood period remains relatively uncharted. In this study, English-speaking children between three and four years of age were investigated for: (i) the development of visual speech perception - lip-reading and visual influence in auditory-visual integration; (ii) the development of auditory speech perception and native language perceptual attunement; and (iii) the relationship between these and a language skill relevant at this age, receptive vocabulary. Visual speech perception skills improved even over this relatively short time period. However, regression analyses revealed that vocabulary was predicted by auditory-only speech perception, and native language attunement, but not by visual speech perception ability. The results suggest that, in contrast to infants and schoolchildren, in three- to four-year-olds the relationship between speech perception and language ability is based on auditory and not visual or auditory-visual speech perception ability. Adding these results to existing findings allows elaboration of a more complete account of the developmental course of auditory-visual speech perception.