Why being left-handed matters for mental health treatment -- ScienceDaily
Since the 1970s, hundreds of studies have suggested that each hemisphere of the brain is home to a specific type of emotion. Emotions linked to approaching and engaging with the world -- like happiness, pride and anger -- lives in the left side of the brain, while emotions associated with avoidance -- like disgust and fear -- are housed in the right.
But those studies were done almost exclusively on right-handed people. That simple fact has given us a skewed understanding of how emotion works in the brain, according to Daniel Casasanto, associate professor of human development and psychology at Cornell University.
That longstanding model is, in fact, reversed in left-handed people, whose emotions like alertness and determination are housed in the right side of their brains, Casasanto suggests in a new study. Even more radical: The location of a person's neural systems for emotion depends on whether they are left-handed, right-handed or somewhere in between, the research shows.
The study, "Approach motivation in human cerebral cortex," is published in Philosophical Transactions of the Royal Society B: Biological Sciences.
According to the new theory, called the "sword and shield hypothesis," the way we perform actions with our hands determines how emotions are organized in our brains. Sword fighters of old would wield their swords in their dominant hand to attack the enemy -- an approach action -- and raise their shields with their non-dominant hand to fend off attack -- an avoidance action