A study by Richard Depue and Yu Fu from Cornell University, New York, published in Frontiers in Human Neuroscience indicates an association between extraversion and dopamine (DA) functioning. The study suggests that if extraversion represents the manifestation of an incentive reward system, then the trait may be in part influenced by the activity of the mesocorticolimbic DA projection system.
Extraversion tends to be manifested in outgoing, talkative, energetic behavior, whereas introversion is manifested in more reflective and reserved behavior.
Jung defined introversion as an “attitude-type characterised by orientation in life through subjective psychic contents”, and extraversion as “an attitude-type characterised by concentration of interest on the external object.
Moreover, he suggested that extraversion is characterized by broad engagement with the environment which is supported by the positive affective state emphasized by others. Jung’s notion suggests that there is a broad class of environmental stimulus that elicits positive affective engagement. According to Richard Depue and Yu Fu, in 1994 Gray extended that notion by arguing that the stimulus class is composed of rewards. Thus, extraversion may represent individual differences in the extent to which environmental rewards elicit positive affective engagement as a means of obtaining those rewards.
As per Gerald Matthews extraversion-introversion is firmly established as a major personality dimension that constitutes part of the popular Five Factor Model of personality traits.
The neuroscience behind extraversion
Gerald Matthews explains that current theory attributes extraversion to individual differences in sensitivity to reward, supported by dopaminergic brain pathways.
Moreover, according to D.H. Saklofske et al.
extraversion is associated with both cortical arousal and the dopaminergic system.
The lower level of cortical arousal and the lower dopaminergic responsiveness found in extraverts is used to explain their greater need for activity, excitement, and general stimulation.
In the Frontiers in Human Neuroscience study the investigators assessed whether extraversion is related to the efficacy of acquiring conditioned contextual facilitation of three processes that are dependent on DA: motor velocity, positive affect, and visuospatial working memory.
They found that extraversion is associated with variation in the acquisition of contexts that predict reward. The individual differences in extraversion may be maintained by activation of differentially encoded central representations of incentive contexts that predict reward. Overall, the major finding was that extraversion is positively related to brain processes that associate contexts with reward.
Importantly, Richard Depue and Yu Fu explained that a major contributor to variation in extraverted behavior is the individual differences in the functional properties of the ventral tegmental area (VTA) DA-nucleus accumbens (NAc)/cortical pathways. Second, variation in DA functioning is manifested by the eliciting effects of environmental incentive stimuli, which as our study suggests can be conditioned incentives as well.
As per the authors, the individual differences in extraversion may be maintained by activation of differentially encoded central representations of incentive contexts that predict reward. The implications of the current study are that, in high extraverts, who are predicted to have a lower threshold of behavioral facilitation, this process will involve:
more frequent activation of incentive;
by a broader network of conditioned contexts that;
elicit more strongly encoded central representations of related rewarding events and their expected outcomes.
Cover Image Credit (Left panel): Chart comparing characteristics of introversion and extraversion (extroversion), Sources: Introverts, Extroverts (chart). Deaf Counseling Center (April 16, 2020). (Archive of chart) (October 2018). “Figure 1. The Introvert-Extrovert Continuum and Traits”. The Asian ESP Journal 14 (5): 38. ERIC Institute of Education Sciences. (ESP=English for specific purposes), (November 2012). “The Correlation Between Students’ Extraversion Personality and Their Writing Skill at Muhammadiyah University of Makassar (a descriptive study).”. Jurnal Pendidikan Bahasa Dan Sastra Inggris 1 (2): 191. Indonesia: Universitas Muhammadiyah Makassar. DOI:10.26618/ejpbi.v1i2.773. “Table 4. Comparison of Introvert behavior and Extrovert behavior”; From: Distinguishing introversion and extraversion (extroversion) – comparison chart; Author: RCraig09, wikimedia.org. (Right panel): Dopamine Pathways. In the brain, dopamine plays an important role in the regulation of reward and movement. As part of the reward pathway, dopamine is manufactured in nerve cell bodies located within the ventral tegmental area (VTA) and is released in the nucleus accumbens and the prefrontal cortex. Its motor functions are linked to a separate pathway, with cell bodies in the substantia nigra that manufacture and release dopamine into the striatum. 17 June 2012. Author: Original: NIDA / Derivative work: Quasihuman; From: Dopamine pathways, wikimedia.org.