Medical science is constantly changing. Ideas about health and biological function that were once assumed to be true are no longer valid. One common misunderstanding from the past is the left versus right brain theory. The idea is still engrained in pop culture, psychologists, neuroscientists and other authorities on the brain have all but discredited the notion of a strictly dichotomous brain. Current thinking is that while particular activity is at times higher in certain critical regions, both hemispheres are typically more or less equal in their activity. Below is a graphic explaining this school of thought on left and right brain dominance.