Developmental Psychology Copyright 1988 by the American Psychological Association, Inc. 1988, Vol. 24, No. 2, 172-182 0012-1649/88/$00.75 Sensory Dominance in Infants: 2. Ten-Month-Old Infants' Response to Auditory-Visual Compounds David J. Lewkowicz New York State Office of Mental Retardation and Developmental Disabilities Institute for Basic Research in Developmental Disabilities, Staten Island, New York A series of studies was conducted with 10-month-old infants in which their response to temporally modulated auditory-visual compounds was examined. The general procedure consisted of first ha- bituating the infants to a compound stimulus (consisting of a flashing checkerboard and a pulsing sound) and then testing their response to it by presenting a series of trials where either one or two temporal attributes of the visual, the auditory, or of both components were changed. When the auditory and visual components were temporally identical, during the habituation phase, the infants only encoded the temporal attributes of the auditory component. When the two components were temporally distinct, or when they were identical but when multiple discriminative cues were avail- able, the infants encoded the temporal aspects of both the auditory and the visual components. When the information context was made more complex, the infants' performance deteriorated, but when the salience of the visual component was increased the infants' performance improved. In sum, although the auditory modality can dominate the visual modality at 10 months of age, the visual modality can process temporal information when the temporal relationship of the informa- tion in the two modalities is distinct. Most of the research on sensory/perceptual development in human infants has been concerned with the functional charac- teristics of single sensory modalities. Only quite recently have investigators begun to examine the way that sensory systems interact with one another during early development (Rose & Ruff, 1987). Most of the research on intersensory interaction has, however, been concerned with the detection ofintersensory equivalence. The implicit assumption of all this work has been that the sensory systems operate on an equal footing. Given that the structural and functional aspects of the different sensory systems develop asynchronously (Bronson, 1982; Gottlieb, 1971; Kasatkin, 1972; Volokhov, 1968), however, the possibility that sensory dominance hierarchies operate during early devel- opment and that their nature may change during this time must be considered seriously. In a companion article, Lewkowicz ( 1988; see pp. 155-171, this issue) reported on a set of studies that investigated 6-month- old infants' processing of temporally based auditory-visual compounds. The general purpose of those studies was to investi- gate the relationship of the auditory and visual modalities when information from each of them competed for the infant's atten- tion. Specifically, these studies systematically determined whether responsiveness to information in one sensory modality This work was supported in part by a grant from the National Foun- dation/March of Dimes and was performed while David Lewkowicz was at Northwestern Medical School and the Evanston Hospital, Evans- ton, Illinois. I thank Ann Dolinko for her assistance in data collection. Correspondence concerning this article should be addressed to David J. Lewkowicz, New York State Institute for Basic Research in Develop- mental Disabilities, 1050 Forest Hill Road, Staten Island, New York 10314. was influenced by the presence of concurrent information in another modality and whether processing of multisensory com- pounds was affected by the temporal complexity of the multi- sensory information. The general method consisted of habituat- ing each infant with an auditory-visual compound composed of a flashing checkerboard and a pulsing sound. To determine what aspects of the compound the infant had encoded, three different types of test stimuli were then presented. One of these test stimuli differed from the habituation stimulus in terms of the temporal characteristics of the visual component, another differed in terms of the temporal characteristics of the auditory component, and the third differed in terms of the temporal characteristics of both components. The most significant and consistent finding from these studies was that the 6-month-old infants did not respond to the changes in the temporal proper- ties of the visual component. That is, they did not dishabituate when the rate of the visual component alone was changed nor when both the rate and duration of the visual component was changed. Even when the intensity of the visual component was increased, relative to that of the auditory component, the in- fants still did not dishabituate to the change in its temporal characteristics. In sum, the findings indicated that when tempo- rally modulated, spatially static visual stimuli competed with temporally modulated, spectrally simple auditory stimuli for the 6-month-old infant's attention, the auditory stimuli domi- nated responding. Although no other systematic studies of sensory dominance in infants have been conducted to date, there is a sizable litera- ture on sensory dominance in children and adults. This litera- ture is consistent in showing that the visual modality dominates the auditory modality across a variety of tasks in both adults (Colavita, 1974; Colavita & Weisberg, 1979; Egeth & Sager, 1977) and children (Hermelin & O'Connor, 1964; O'Connor & Hermelin, 1965). The finding of auditory dominance at 6 172