Introduction:
 Traits related to approach versus avoidance tendencies—such
as sensation seeking—have received some of the most attention from researchers
interested in the biological bases of personality. One such trait is
extraversion-introversion. In the following section, we will review the two
major theories linking differences in brain functioning to differences in
extraversion. First, we will examine the model of the biological bases of
extraversion-introversion proposed by Hans Eysenck back in the 1960s. He
argued that all people seek an optimal level of cortical arousal, but
whereas some people (namely, introverts) receive more arousal from internal
sources, others (namely, extroverts) must seek more arousal from external
sources. While the behavioral research tends to be supportive of Eysenck's
model, neurophysiological research has yet to corroborate some of the
proposed underlying mechanisms. Thus, we will also examine a more recent
model put forth by Jeffrey Gray which explains extraversion-introversion in
terms of two distinct brain systems: a behavioral approach system (BAS) and
a behavioral inhibition system (BIS). When BAS activity exceeds BIS
activity, a person appears extraverted. When BIS activity exceeds BAS
activity, a person appears introverted. Both models have their strengths and
weaknesses, but clearly the theorizing and research in this area is still in
its infancy, and more research utilizing recent developments in brain
imaging is needed.
|
|
