title: Search asymmetry and eye movements in infants and adults.
abstract: Search asymmetry is characterized by the detection of a feature-present target amidst feature-absent distractors being efficient and unaffected by the number of distractors, whereas detection of a feature-absent target amidst feature-present distractors is typically inefficient and affected by the number of distractors. Although studies have attempted to investigate this phenomenon with infants (e.g., Adler, Inslicht, Rovee-Collier, & Gerhardstein in Infant Behavioral Development, 21, 253-272, 1998; Colombo, Mitchell, Coldren, & Atwater in Journal of Experimental Psychology: Learning, Memory and Cognition, 19, 98-109, 1990), due to methodological limitations, their findings have been unable to definitively establish the development of visual search mechanisms in infants. The present study assessed eye movements as a means to examine an asymmetry in responding to feature-present versus feature-absent targets in 3-month-olds, relative to adults. Saccade latencies to localize a target (or a distractor, as in the homogeneous conditions) were measured as infants and adults randomly viewed feature-present (R among Ps), feature-absent (P among Rs), and homogeneous (either all Rs or all Ps) arrays at set sizes of 1, 3, 5, and 8. Results indicated that neither infants' nor adults' saccade latencies to localize the target in the feature-present arrays were affected by increasing set sizes, suggesting that localization of the target was efficient. In contrast, saccade latencies to localize the target in the feature-absent arrays increased with increasing set sizes for both infants and adults, suggesting an inefficient localization. These findings indicate that infants exhibit an asymmetry consistent with that found with adults, providing support for functional bottom-up selective attention mechanisms in early infancy.
authors.affiliation: 5030 TEL Building, York University, 4700 Keele St., Toronto, ON, M3J 1P3, Canada, adler@yorku.ca.
authors.forename: Scott A
authors.initials: SA
authors.lastname: Adler
authors.forename: Pamela
authors.initials: P
authors.lastname: Gallego
mesh_terms: D000328:Adult; D000375:Aging / Q000502:physiology*; D000704:Analysis of Variance; D001288:Attention / Q000502:physiology*; D002657:Child Development / Q000502:physiology*; D002675:Child, Preschool; D005260:Female; D007839:Functional Laterality / Q000502:physiology; D006801:Humans; D007223:Infant; D008297:Male; D011930:Reaction Time / Q000502:physiology; D012016:Reference Values; D012044:Regression Analysis; D012438:Saccades / Q000502:physiology*; D065855:Spatial Processing / Q000502:physiology*; D014796:Visual Perception / Q000502:physiology*; D055815:Young Adult