IOWA CITY, Iowa -- A University of Iowa study adds to growing evidence that being shy or outgoing may be all in your head. Investigators looking at cerebral blood flow and personality found more conclusive signs of different brain activity in introverts and extroverts.
This is the first study to reveal the connections between activity of the thalamus and introversion and extroversion, said Debra L. Johnson, Ph.D., UI assistant research scientist in psychology and the study's lead investigator. "We found more evidence that people might be shy or outgoing because of the way their brains are structured."
Previous studies have shown that introversion and extroversion are based on variations in brain function, but those studies did not describe all the locations found in this study. The UI researchers examined 18 healthy individuals using positron emission tomography (PET) scans, which can provide a high-resolution image of the entire head.
The PET 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 typically thought to be more involved in sensory processing such as listening, watching or driving.
The differences in cognitive style and sensory-processing relate to the qualities associated with introversion and extroversion. True introverts are quiet, inwardly focused and reclusive. Extroverts are gregarious, socially active and sensation seeking.
"Introverts get more of their stimulation internally, whereas extroverts seek outside sources," Johnson said. "Extremely introverted and extroverted personalities are two ends of a continuum, with most people falling somewhere in between."
Johnson added, "The implication is that one pers
'"/>
Contact: Becky Soglin
becky-soglin@uiowa.edu
319-335-6660
University of Iowa
29-Mar-1999