Relationship of ear specialization to degree of task difficulty, sex, and lateral preference

Children in Grades 2 and 6 nested in age, sex, and lateral-preference groups were administered two dichotic listening tests (digit and environmental sound). There was a right-ear advantage for verbal stimuli which did not increase with age, supporting the invariance models of the development of verbal laterality past 5 to 6 years of age. The percentage of left-ear accuracy for verbal stimuli relative to the right ear decreased with task difficulty. Girls were more accurate than boys when recalling verbal stimuli and the older boys were more accurate than the other children when identifying environmental sounds. In recalling nonverbal stimuli, boys showed a left-ear advantage and out-performed girls, who showed a right-ear advantage. The sex difference in ear advantage increased with task difficulty. There was an over-all increase in accuracy with age when identifying both verbal and nonverbal stimuli with the exception of the ambidextrous children, who demonstrated low accuracy scores for the environmental sound stimuli across age groups.