Abstract
Most studies of infant cognition focus on group data from single domains. Yet, without the multi-domain testing of the same infants longitudinally, such data cannot be used to evaluate whether the timing of cognitive change occurs in a domain-general or a domain-specific way. We present the results of a longitudinal study pooling data from three European laboratories set up identically. Over 100 healthy, monolingual infants each underwent multi-domain testing at 6 and again at 10 months in six experimental tasks (speech processing, face processing, and action/event processing), as well as a videotaped 3-minute recording of mother/infant dyads in a play session with an identical set of toys. Previous research examined the effects of maternal sensitivity only on general intelligence measures, but our approach is novel in that it assessed dyadic effects on specific cognitive domains, attempting to pinpoint in finer detail the effects of mother-infant dyadic interaction on the timing of cognitive change. Our findings highlight the importance of a multi-domain approach, in that unlike the assumptions drawn from cross-sectional data, our longitudinal study yielded different developmental timing across domains within the same infants. Our results also highlight a crucial difference: at the group level 6- and 10-month-olds display the expected effects found in previous research, but when re-analysed according to mother-child interaction ratings, the quality of dyadic interaction style turned out to subtly foster or delay development in domain-specific and age-specific ways, contributing to the range of individual differences in timing that we observe in cognitive development over the first year of life.