Visual Processing Deficits in Children With Slow RAN Performance

Two groups of 8- to 10-year-olds differing in rapid automatized naming speed but matched for age, verbal and nonverbal ability, phonological awareness, phonological memory, and visual acuity participated in four experiments investigating early visual processing. As low RAN children had significantly slower simple reaction times (SRT) this was entered as a covariate in all subsequent data analyses. Low RAN children were significantly slower to make same/different judgments to simple visual features, non-nameable letter-like forms and letters, with difference in SRT controlled. Speed differences to letter-like forms and letters disappeared once RTs to simple visual features were controlled. We conclude that slow RAN children have difficulty in discriminating simple visual features that cannot be explained in terms of a more general speed of processing deficit, a deficit in making same/different judgments, or to differences in word reading ability.