SHIFTS IN CHILDRENS EAR ASYMMETRY DURING VERBAL AND NONVERBAL AUDITORY-VISUAL ASSOCIATION TASKS - A VIRTUAL STIMULUS EFFECT

Dichotic consonant-vowel-consonant (CVC) syllables were presented to 9 6 right-handed children between the ages of 8 and 12 years. Children w ere assigned either to a ''code'' condition that entailed translating the CVCs into English words or to a ''bird'' condition in which the CV Cs had to be matched to cartoons of birds. A differential ear asymmetr y for the code and bird tasks developed linearly across four blocks of trials. By Block 4, the code task yielded a significant right-ear adv antage and the bird task yielded no ear advantage. The results are inc onsistent with any model that attributes ear asymmetries entirely to f ixed structural characteristics of the nervous system. Instead, ear as ymmetries are influenced by the subject's categorization of the stimul i, i.e., by ''virtual stimuli''. These appear to be constructed over t ime (blocks of trials).