Do auditory perceptual asymmetries develop?
Two studies investigated dichotic listening performance in school-age children. The first employed lists of numbers, single pairs of nonsense syllables, and single pairs of words. None of these materials produce any age-related effects, although a strong right-ear effect was observed with all. When subjects were permitted free recall of number lists, they tended to initiate report with items from the right ear, indicating an attentional bias towards the right. When this was corrected statistically, most of the laterality effect disappeared, suggesting that attentional biases make a major contribution to observed laterality effects. The second study involved word pairs, environmental sounds, and a word pair condition in which the deployment of attention was controlled by instruction. The two verbal tasks again showed a large right-ear effect, but no laterality effects were found for environmental sounds. The monitoring experiment corroborated the earlier finding that children tend to bias their attention to the right, but this attentional bias could not account for the whole laterality effect. It is concluded that a right-ear perceptual advantage exists for verbal material in children, and that there is no evidence for any change in this laterality effect with age.