Developmental changes during childhood in single-letter acuity and its crowding by surrounding contours

Crowding refers to impaired target recognition caused by surrounding contours. We investigated the development of crowding in central vision by comparing single-letter and crowding thresholds in groups of 5-year-olds, 8-year-olds, 11-year-olds, and adults. The task was to discriminate the orientation of a Sloan letter E. Single-letter thresholds, defined as the stroke width forming the smallest discriminable E, were worse than those of adults …