SHY OR OUTGOING? BLAME IT ON YOUR BRAIN.

A University of Iowa, Iowa City, study adds to growing evidence that being shy or outgoing may be all in your head. Investigators looking at cerebral blood flow and personality have found more conclusive signs of different brain activity in introverts and extroverts. Debra L. Johnson, assistant research scientist in psychology, indicates that "We found more evidence that people might be shy or outgoing because of the way their brains are structured, not because of experiences they've had."

The researchers examined 18 healthy individuals utilizing positron emission tomography (PET) scans, which can generate a high-resolution image of the entire head. The scans revealed that introverts have more activity in the frontal lobes of the brain and anterior, or front, thalamus. These areas are activated when a person's brain takes on internal processing such as remembering, problem-solving, and planning. Extroverts exhibit more activity in the anterior cingulate gyrus, temporal lobes, and posterior thalamus. These areas are...