The development of the right ear advantage in dichotic listening with focused attention.

The influence of selective attention on cerebral asymmetry in 6, 8 and 10 year old children was studied using pre-cued dichotic recall of 1 to 4 pairs of digits. A constant right ear advantage for correct recall from the attended ear and intrusions from the unattended ear was found in all three age groups. The ear difference increased with set size and across serial position with a set size of 4 digit pairs. Thus the number of items in acoustic memory determined the degree of lateral asymmetry. The ability to focus attention on the left ear improved between 6 and 8 years. It was concluded that control of directed attention, which improves with development, and left hemisphere specialization for speech processing, which remains constant, both determine performance in dichotic verbal listening.