Abstract
Visual search studies have shown that 3-month-olds exhibit "pop out" and feature search similar to adults (Adler & Orprecio, 2006), but that infants do not accomplish a conjunction search until around 6 months of age (Bhatt, Bertin & Gilbert, 1999). Previous conjunction search research with infants, however, has assessed their search behavior using habituation and preferential looking paradigms, which measure performance in seconds rather than milliseconds as is the case in studies of adults’ search behavior. To allow for direct comparison of the two ages and comparable assessment of the relative development of search and attentional mechanisms, this study measured infant and adult saccadic latencies in milliseconds to localize a target in both conjunction and feature searches. Infants and adults were presented with either feature or conjunction visual search arrays at 3 different set sizes (5, 8, 10) with the target (a green or red "X" or "O") being either present or absent. Surrounding distractors differed based on a single unique feature (shape or color) or a conjunction of features (shape and color). Results indicated that both infants’ and adults’ saccadic latencies exhibited relatively flat functions across set sizes in the feature search, with infants’ latencies being approximately 100 msec slower than adults’. In the conjunction search, in contrast, adults’ saccadic latencies to localize the target increased as a function of set size, whereas infants’ latencies did not increase with set size. Infants’ latencies were also approximately 200 msec slower than adults’ in the conjunction search. These results, consistent with previous studies, suggest a developmental progression in the capacity to conduct a conjunction search but that feature search is evident early in infancy. One possibility is that the attentional resources needed to allocate to the two features in the conjunction search have not yet fully developed at 3 months of age.
Meeting abstract presented at VSS 2012