title: Brain responses to audiovisual speech mismatch in infants are associated with individual differences in looking behaviour.
abstract: Research on audiovisual speech integration has reported high levels of individual variability, especially among young infants. In the present study we tested the hypothesis that this variability results from individual differences in the maturation of audiovisual speech processing during infancy. A developmental shift in selective attention to audiovisual speech has been demonstrated between 6 and 9 months with an increase in the time spent looking to articulating mouths as compared to eyes (Lewkowicz & Hansen-Tift. (2012) Proc. Natl Acad. Sci. USA, 109, 1431-1436; Tomalski et al. (2012) Eur. J. Dev. Psychol., 1-14). In the present study we tested whether these changes in behavioural maturational level are associated with differences in brain responses to audiovisual speech across this age range. We measured high-density event-related potentials (ERPs) in response to videos of audiovisually matching and mismatched syllables /ba/ and /ga/, and subsequently examined visual scanning of the same stimuli with eye-tracking. There were no clear age-specific changes in ERPs, but the amplitude of audiovisual mismatch response (AVMMR) to the combination of visual /ba/ and auditory /ga/ was strongly negatively associated with looking time to the mouth in the same condition. These results have significant implications for our understanding of individual differences in neural signatures of audiovisual speech processing in infants, suggesting that they are not strictly related to chronological age but instead associated with the maturation of looking behaviour, and develop at individual rates in the second half of the first year of life.
authors.affiliation: Institute for Research in Child Development, School of Psychology, University of East London, Water Lane, London, E15 4LZ, UK.
authors.forename: Elena
authors.initials: E
authors.lastname: Kushnerenko
authors.forename: Przemyslaw
authors.initials: P
authors.lastname: Tomalski
authors.forename: Haiko
authors.initials: H
authors.lastname: Ballieux
authors.forename: Helena
authors.initials: H
authors.lastname: Ribeiro
authors.forename: Anita
authors.initials: A
authors.lastname: Potton
authors.forename: Emma L
authors.initials: EL
authors.lastname: Axelsson
authors.forename: Elizabeth
authors.initials: E
authors.lastname: Murphy
authors.forename: Derek G
authors.initials: DG
authors.lastname: Moore
mesh_terms: D000367:Age Factors; D001921:Brain / Q000254:growth & development / Q000502:physiology*; D005071:Evoked Potentials; D005133:Eye Movements; D005260:Female; D006801:Humans; D007223:Infant; D008297:Male; D011597:Psychomotor Performance; D013067:Speech Perception; D014796:Visual Perception
keywords: McGurk illusion; audiovisual integration; audiovisual mismatch response; event-related potentials (ERPs); eye-tracking