An in-depth look at saccadic search in infancy

Abstract

Two questions were posed in the present study: (1) Do infants search for discrepant items in the absence of instructions? We outline where previous research has been inconclusive in answering this question. (2) In what manner do infants search, and what are the fixation and saccade characteristics in saccadic search? A thorough characterization of saccadic search in infancy is of great importance as a reference for future eye-movement studies in infancy. We presented 10-month-old infants with 24 visual search displays in two separate sessions within two weeks. We report that infant saccadic search performance at 10 months is above what may be expected by our model of chance, and is dependent on the specific target. Infant fixation and saccade characteristics show similarities to adult fixation and saccade characteristics in saccadic search. All findings were highly consistent across two separate sessions on the group level. An examination of the reliability of saccadic search revealed that test-retest reliability for oculomotor characteristics was high, particularly for fixation duration. We suggest that future research into saccadic search in infancy adopt the presented model of chance as a baseline against which to compare search performance. Researchers investigating both the typical and atypical development of visual search may benefit from the presented results.