When is between-hemisphere division of labor advantageous?

Division of labor between the hemispheres is sometimes advantageous. Merola and Liederman (1985) have shown that adolescents' naming performance is superior when two different kinds of letter input are divided between the hemispheres than when both kinds of letter input are projected to a single hemisphere. We now investigated whether the advantage of between-hemisphere division of inputs increases from adolescence to adulthood; occurs when a secondary, concurrent verbal memory task is added; and corresponds with superior performance on the secondary task. Results indicated that use of the hemispheres as insulated work stations increased from adolescence to adulthood, and did not diminish when memory was stressed. However, between-hemisphere division of labor for the primary task did not facilitate secondary task performance.