The purpose of this study was to establish whether individual differences in the amount of visual attention

to mouth articulations between 6 and 9 months of age are associated with neural signatures of AV speech processing (the ERP AVMMR). Given that previous eye-tracking JQ1 datasheet data has shown the presence of developmental change in visual attention to speaking mouth between 6 and 9 months of age (Lewkowicz & Hansen-Tift, 2012; Tomalski et al., 2012), we expected to see a related change in brain responses to AV speech within the same age range. In particular, we asked whether the increased looking time to the mouth between 6 and 9 months of age indicates either: (i) an increased interest in AV mismatch or (ii) an enhanced use of visual speech cues in an attempt to integrate the auditory and visual information. We measured ERPs in response to congruent and incongruent

AV speech cues, and subsequently recorded face-scanning patterns using eye tracking while infants watched the same stimuli. We found a strong association between neural responses (the AVMMR) and the length of looking to the mouth in the same condition (VbaAga-combination). The amplitude of AVMMR (290–390 ms from sound onset) in find protocol the ERP task was strongly negatively correlated with looking times to the mouth during the presentation of the VbaAga-combination stimulus in the subsequent eye-tracking task. The AVMMR is thought to reflect quick automatic brain detection of mismatch between cues from two modalities, similarly to the pre-attentive auditory-only mismatch response (Kushnerenko et al., 2008). Previously it has been shown that the auditory mismatch response in infants undergoes a prolonged maturational process Forskolin ic50 with a large positivity gradually decreasing in amplitude from the age of 3 months

until approximately the end of the first year of life (Kushnerenko et al., 2002b; Kushnerenko, E., Van den Bergh, B.R.H., & Winkler, I., (under review); Morr et al., 2002). Moreover, while no group differences were found in auditory ERPs between 6 and 9 months of age, large inter-individual variability was reported (e.g., Kushnerenko et al., 2002a,b), suggesting that this maturational change occurs at different rates in individual infants and is rather loosely related to chronological age (Kushnerenko et al., 2002b). We suggest that the same principle may be applicable to maturation of AV speech processing. Indeed, in the present study the AVMMR amplitude was associated with a specific looking preference rather than with chronological age. The AVMMR was only observed in the NMP subgroup which, according to the recent study of Lewkowicz & Hansen-Tift (2012), could be considered less mature in AV processing.