Converging Behavioral and Neural Measures of Attention in Human Infants

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Attention is the filter through which all sensory inputs must pass. Therefore, attention is the gateway for perception, learning, and memory. Current understanding of attention in infancy is based on studies that measure the direction and duration of visual fixation of visual stimuli. This project investigates the likelihood that some proportion of infant visual attention constitutes the absence of active processing either due to a blank stare or to attention being directed to the periphery. If this hypothesis is correct then current findings in the literature based on infant looking may provide an inaccurate picture of infant attention and, thus, of infant processing in multiple domains of psychological functioning. The principal goal of the present project is to employ simultaneous converging measures to assess overt and covert visual attention in human infants and to relate those measures to individual differences in outcome on classic infant multisensory integration and perceptual learning/discrimination tasks. Measures of overt infant visual attention will be obtained with standard methods using both human observers and commercial eye trackers. Measures of covert visual attention will utilize an EEG frequency-tagging technique which provides a continuous measure of the brain's response to a flickering stimulus (or an annulus surrounding that stimulus) and can reveal when covert attention is reduced (or absent) even when overt attention is directed to a stimulus either because the infant is just staring or directing attention elsewhere. Our converging measures will provide moment-to-moment changes in infant looking at either one or two simultaneous stimuli and brain responses to the stimuli flickering at different temporal frequencies. Using time resolved multivariate regression, we will estimate the patterns of overt and covert attention that best predict the perceptual and memory performance during a post-test following the encoding phase in experiments examining infant matching of faces and vocalizations, infant learning and discrimination of visual objects, and infant categorization of visual objects. Overall, the current project promises to provide a methodologically innovative way to extract a purer measure of active attention in infancy than is currently possible through concurrent access to a neural marker of covert attention. This, in turn, will provide a powerful new tool for assessing the role of active attention in multiple domains of cognitive functioning in infancy in both typical and atypical populations.