Book excerpt: Is "right-brain" thought essentially creative, and "left-brain" strictly logical? Joseph B. Hellige argues that this view is far too simplistic. Surveying extensive data in the field of cognitive science, he disentangles scientific facts from popular assumptions about the brain's two hemispheres. In Hemispheric Asymmetry, Hellige explains that the "right brain" and "left brain" are actually components of a much larger cognitive system encompassing cortical and subcortical structures, all of which interact to produce unity of thought and action. He further explores questions of whether hemispheric asymmetry is unique to humans, and how it might have evolved. This book is a valuable overview of hemispheric asymmetry and its evolutionary precedents.