Abstract
A key demonstration of the preattentive and attentive mechanisms thought to underlie the allocation of attention in adults has been the exhibition of an asymmetry in visual search. The asymmetry is characterized by search for a feature-present target amidst feature-absent distractors being more efficient and less affected by the number of distractors than search for a feature-absent target amidst feature-present distractors. Though studies have attempted to investigate this phenomenon with infants (e.g. Adler, Inslicht, Rovee-Collier, & Gerhardstein, 1998; Colombo, Mitchell, Coldren, & Atwater, 1990), due to their methodological limitations, their findings have been unable to definitively establish the functioning of visual search mechanisms in infants as in adults. The present study, therefore, assessed eye movements as a means to examine visual search asymmetry in 3-month-olds relative to adults. Saccade latencies to a target were measured as infants and adults randomly viewed feature-present (R among Ps), feature-absent (P among Rs), and homogenous (either Rs or Ps) search arrays at set sizes of 1, 3, 5 and 8. Results indicated that neither infants' nor adults' saccade latencies to the target in the feature-present arrays were affected by increasing set sizes, suggesting that the target popped out and search was efficient. In contrast, saccade latencies to the target in the feature-absent arrays increased with increasing set-sizes for both infants and adults, suggesting that search was inefficient. The search functions were similar for infants and adults, with the exception that infants' latencies for feature-present targets were consistently greater than adults'. These findings indicate that infants exhibit a search asymmetry similar to adults, providing additional support for functional visual search and selective attention mechanisms in early infancy.