June 21, 2018
New research suggests that the way the brain directs the behaviors of approach and avoidance is based on your dominant hand – a finding that eventually could spark changes in mental health treatment.
For decades, researchers believed that the left side of the brain processes approach-oriented emotions like happiness or anger, while the right side processes avoidance-oriented emotions, like fear.
But Cornell University researchers now believe that may only be true for right-handed people. That's because prior research primarily was conducted on right-handed people.
Their study, published Monday in a scientific journal, concluded that the brain is set up oppositely among left-handers. And that could impact the way they receive neural therapy, a treatment sometimes given to people suffering from depression or recalcitrant anxiety.
During neural therapy, the left-side of the brain is given mild electrical stimulation designed to boost approach-oriented emotions. But the new research suggests that could actually decrease life-affirming emotions among left-handers, because the wrong side of the brain is being stimulated.
"If you give left-handers the standard treatment, you're probably going to make them worse," lead researcher Daniel Casasanto said in a statement.
"And because many people are neither strongly right- nor left-handed, the stimulation won't make any difference for them, because their approach emotions are distributed across both hemispheres."
The research suggests that only strong right-handers should receive the standard treatment, Casasanto said. Strong-left-handers should receive the opposite treatment, while people in the middle should refrain from neural therapy.
However, Casasanto stressed that more research is necessary.
The Cornell study involved 25 healthy individuals who received a similar brain stimulation treatment for five straight days. Afterward, the participants reported how strongly they felt emotions like enthusiasm, pride and alertness.
The participants reported positive emotions when they were stimulated on the same side as their dominant hand. But when they were stimulated on the opposite side, they reported no change or fewer approach-oriented emotions.
The researchers dubbed their findings as the "sword and shield hypothesis," noting that sword fighters traditionally hold their weapon in their dominant hand – which attacks – and their shield in their non-dominant hand – which protects.
"Your dominant hand gets the thing you want and your non-dominant hand pushes away the thing you don't," Casasanto said.
