Autonomic correlates of individual differences in sensitization and look duration during infancy

Patterns of infant visual attention have been attributed to both the proces ses of habituation and arousal. Previous research has linked individual dif ferences in arousal (sensitization) with measures from habituation that hav e been associated with the efficiency of stimulus encoding (look duration). The aim of current study was to validate individual differences in these r ealms with a convergent measure of attention based on heart rate (HR) that might presumably reflect autonomic function and arousal. In contrast with p revious work, neither habituation nor look durations differed significantly as a function of the presence of sensitization. HR variables did not diffe rentiate infants who showed sensitization from those who did not. HR analys es on individual differences in look duration, however, yielded two signifi cant findings: short-looking infants maintained higher levels of HR variabi lity than long-looking infants across the session, and long-looking infants had greater HR accelerations to stimulus onsets than did short-looking inf ants. (C) 2000 Elsevier Science Inc. All rights reserved.