Brain Laterality — Beyond the Basics

In the present paper, I selectively review a series of studies conducted in our laboratory over the last decade related to brain laterality, both experimentally and clinically. The studies reviewed have for most part utilized the dichotic listening and visual half-field techniques for lateralizing stimulus presentations. Three major conceptual distinctions in brain laterality are discussed in the paper: hemispheric specialization versus hemispheric activation, functional versus structural laterality, and hardwired versus dynamic modulatory laterality. A fourth distinction is between cognitive and physiological laterality. It is argued in the paper that left-right asymmetrical function is not only related to perceptual/cognitive functions subserved by the cortical hemispheres, but also involves subcortical structures and peripheral physiology, including the autonomic and endocrine systems. Thus, although research on laterality has been in the mainstream of general psychology and neuropsychology for the last 30-50 years, we have still probably only uncovered the tip of the iceberg with respect to the psychological processes and systems that are related to the asymmetrical structure and function of the brain.