Biological Perspectives of Personality Traits: Introversion VS Extraverson

Personality Traits

Personality traits are stable psychological dispositions that behave in a certain way.  All traits have three properties: being stable over time, consistent across situations, and have individual differences.  Examples that are not personality traits are an adolescence’s identity confusion since it is not stable over time.  Short lived affective states such as surprise that are not consistent across all situations and color vision since it is not a unique difference that enables a personality traits being present.

Introversion and Extraversion

Introversion and extraversion are explained in the degree of difference between them.  The spectrum of extraversion is the quantity and intensity of interpersonal interaction, activity level, need for stimulation, and capacity for joy.  A high degree of extraversion would describe someone who is sociable, active, talkative, person-oriented, optimistic, fun-loving, and affectionate.  A typical low degree of extraversion would be explained as reserved, sober, exuberant, aloof, task-oriented, retiring, and quiet.  The high degree of extraversion would be an extravert and a low degree of extraversion would describe an introvert. 

Biological Roots

Extraversion and introversion are regulated by the reticular activation system (RAS).  The RAS is what controls the awakening and putting to sleep part of the brain.  Individual differences in the baseline cortical arousal level of an individual predominantly defines whether an individual is an introvert or extravert.  The cortical arousal level could be described as the brain volume control of stimulation.  Ranging from low being sleep to high being manic and the optimal middle level being alertness.  The baseline cortical arousal level of an extravert is boredom therefore being naturally understimulated.  The baseline cortical arousal level of an introvert is vigilant therefore being naturally overstimulared.  An extravert naturally seeks stimulation slowly gathering energy throughout the day naturally inclines individual to be a night time person.  An introvert is stimulation shy so is slowly exhausted by the end of the day, being more prone to being a morning person.

Summary

An extrovert is understimulated therefore stimulation thirsty since there cortical arousal level is lower.  Extraverts are easily bored and tend to be more night time oriented.  An introvert is overstimulated and stimulation shy since they have a higher cortical arousal baseline.  Introverts get wired easily and more proned to being a morning oriented.  The degree of either low to high extraversion of the individual defines whether the person is predominantly introverted or extraverted.