Developmental changes in dichotic right ear advantage (REA).

A cross-sectional, dichotic listening study of 210 right-handed, middle-class children four to ten years old used thirty pairs of one-syllable words and thirty pairs of four-syllable numbers to assess the developmental course of ear asymmetry. A significant decrease in REA for both word and number pairs was found. Although right-ear and left-ear performance both increased with age, the developmental gain in left-ear performance was greater than the gain in right-ear performance, thus resulting in a decrease in REA with age. The results are discussed with respect to investigations which found no change in REA during development and a structural model based on the development of interhemispheric connectivity is proposed to explain the findings.