Interhemispheric Interaction: Models, Paradigms and Recent Findings

Abstract

There is now a great deal of evidence that information processing differences between the left and right cerebral hemispheres can have important consequences for information processing in neu-rologically normal humans. Until recently, the emphasis has been on learning as much as possible about the processing abilities and propensities of each hemisphere and not so much on the manner in which the two hemispheres interact to form an integrated processing system. As humans look around their world, hear sounds and touch objects it is the case that most information is presented to both hemispheres and it is often the case that both hemispheres are capable of generating a behavioral response to the stimulation. We have only limited knowledge about the nature of interhemispheric interactions in such situations. With these things in mind, the present chapter examines some of the ways that interhemispheric interaction might be studied by comparing performance in situations involving only one hemisphere to performance in similar situations involving both hemispheres. Specifically, consideration will be given to dual-task studies of interference, to studies demanding cross-hemispheric integration of information and to investigation of the effects of simultaneous presentation of the same stimulus information to both hemispheres.