Comment on "Information processing in the cerebral hemispheres: selective activation and capacity limitations" by...

The attentional model of hemisphere differences proposed by Kinsbourne is reviewed, and some of the difficulties inherent in this model are pointed out. In particular, the difficulty of distinguishing shifts in the allocation of attention from changes of strategy is underlined, and the fact that the effect of imposing a concurrent memory load is uncertain, sometimes priming and sometimes depressing the performance of the loaded hemisphere, is seen as seriously limiting the predictive power of the model. Hellige, Cox, and Litvac attempted to clarify several aspects of Kinsbourne's theory. In their studies concurrent verbal loads produced complex and variable changes in the performance of both hemispheres. To explain these, they postulate a dual mechanism whereby general activation primes the performance of both hemispheres while selective activation acts to prime or to depress the performance of the left hemisphere. Although they succeeded in identifying some of the factors that govern the effects of selective activation, the effects of general activation are uncertain, so the overall outcome of concurrent memory loading is still difficult to predict.