Imagine the difference between two babies in a nursery of a hospital: while the first one reacts positively to every smile, the second avoids any contact and feels at ease only in a quiet environment. What made these differences occur in infants is something that puzzled psychologists for many years. One of the explanations of this difference comes from the contribution of genetics to personality.
As research based on the studies of twins and families showed, the heritability rate of extraversion is 40 to 60 per cent (Jang et al., 1996; Vukasović & Bratko, 2015). But not everything can be attributed to that. Parenting style, cultural factors, peers, and personal choices play their role as well in the development of extraversion during people’s lives.
Read More: Prosocial Behaviour: What Really Drives Us to Help Strangers?
What Extraversion Actually Means
The feature of extraversion is one of the five main personality dimensions alongside openness to experience, agreeableness, conscientiousness, and neuroticism. According to trait theories, and especially the Five-Factor Model of personality, extraversion is considered to be the personality trait of sociability, talkativeness, assertiveness and energetic behaviour stemming from social contacts (Jang et al., 1996).
Swiss psychiatrist Carl Jung, who was the first to describe the trait of extraversion within the framework of analytical psychology, provided a different definition. His theory states that the energy of an extravert is directed at the external world, other people and events taking place in the external world, while the energy of an introvert is focused on his thoughts and ideas.
For him, introversion is not only the absence of extraversion but a completely different approach to perceiving the world with its own sources of energy and positive features. At a later stage, Hans Eysenck reinterpreted the trait of extraversion in terms of the physiological difference in cortical arousal (the phenomenon will be discussed in more detail below).
As a rule, all these concepts have one thing in common: extraversion and introversion are placed on the continuum, and not on the dichotomy. These features should therefore be regarded as tendencies, rather than polar opposites. Most people exhibit intermediate levels of these tendencies and other associated features of sociability, assertiveness, positive emotionality and sensation seeking (Jang et al., 1996).
The reason why it is crucial to know the nature of extraversion is the following: this type of personality has a tremendous influence on one’s way of life because it affects interpersonal relationships and one’s well-being. Nevertheless, there is a question of whether extraversion is a consequence of biological predisposition or the influence of upbringing and life experience.
Luckily enough, there is an answer to this question since it is known that both biological predisposition and life experience have a great influence on extraversion. This statement can be supported by the results of the twin studies since there is a great amount of genetic contribution to the development of extraversion (about 36–53% of variance in the extraversion dimension), which is independent of the common family environment and, therefore, the individual experience makes people different in extraversion (Jang et al., 1996; Vukasović & Bratko, 2015).
Read More: Is Attachment Avoidance Genetic? The Role of OXTR rs53576 and Environmental Influence
The Brain’s Reward System and Sociability
One of the most obvious biological reasons for extraversion is the effect of the neurotransmitter dopamine, responsible for motivation, pleasure, and anticipation of rewards. According to this theory, people who are characterised by extraverted personality traits have an overactive dopamine-reward system in the brain. That is, they respond more strongly to the anticipation of a pleasant or exciting event, such as communication, praise, or thrill (Depue & Collins, 1999).
Brain imaging techniques supported this theory. The level of dopamine activation in extraverts was higher than in introverts when exposed to reward-related stimuli. The increased level of dopamine was associated with faster learning of reward-inducing situations (Depue & Fu, 2013). This could be the physiological reason why extraverts are inclined to participate in social gatherings. They also seek new experiences and take on leadership roles because their brains perceive these activities as rewarding.
The reward-sensitivity model mentioned above could also be related to the theory of psychologist Hans Eysenck. According to this theory, introverts have a high baseline arousal level, so they tend to avoid excessive stimulation. In contrast, extraverts have a low baseline arousal level and therefore look for stimulation in the environment (as cited in Fabio & Corace, 2016). Although researchers later revised the theory, its fundamental assumption remains: extraversion directly connects to the brain’s reward and arousal systems.
Nature Meets Nurture: Environmental Influences
It is nature that makes a predisposition, while nurture determines how it is going to manifest itself. Researchers of infant temperament studies discovered that there exists a genetic predisposition toward “surgency.” These inclinations relate to sociability and activity, although parents can influence them through their behaviour (Rothbart, as cited in Encyclopedia on Early Childhood Development, 2012).
Biologically extraverted children tend to receive more care and attention. In contrast, an overprotective parenting style may lead to even greater introversion among naturally introverted children (Schermerhorn & Bates, as cited in Encyclopedia on Early Childhood Development, 2012). Researchers call this the “goodness-of-fit” between the child’s temperament and their surroundings.
In addition to that, culture, education, socialisation, and birth order are also important determinants of social inclinations. An individual with a genetic predisposition toward extraversion may develop inhibited social behaviour when their family and culture discourage assertiveness. The opposite may also be true. The concept also correlates with the idea that non-shared environmental factors have a greater impact on personality development. These factors include the unique experiences gained by individuals regarding their own life, rather than the shared family environment (Jang et al., 1996).
Read More: The Psychology of Consistency
Can Extraverted Behaviour Change Over Time?
There is no consistency in personality traits across time periods. Personality stability increases with increasing age. It varies from .31 for children to .74 in adults aged 50 to 70 years, according to a meta-analytic analysis carried out by Roberts & DelVecchio (2000). However, there are no personality traits that are totally stable at any age. Experiments have scientifically proven the fact that people can try to become more extraverted.
According to Hudson and Fraley (2015), college students set the goal of becoming more extraverted. They worked towards it and became more extraverted over a period of 16 weeks. This change was greater than that observed in students who did not have this goal. It was helpful to have a specific task, because having an unspecified goal like becoming more sociable helped little. The interesting thing to note about the study is that extraversion feels good. This is irrespective of the extraversion of the person (Fleeson et al., 2002).
Read More: How the Brain’s Anti-Reward System Fuels Cocaine Relapse
Conclusion
Do genes determine whether someone is an extravert, or do people develop extraversion later in life? It appears to be the case that both elements have their effect here. The genetic elements account for roughly fifty per cent of individual differences in sociability. Dopamine controls variations in the brain’s reward system. They explain why some people feel innately rewarded for social interaction (Jang et al., 1996; Depue & Collins, 1999). However, parenting, cultural factors, and experience affect the way in which this genetic tendency expresses itself. Studies show that people can deliberately cultivate extraverted personality traits (Hudson & Fraley, 2015).
References +
- Depue, R. A., & Collins, P. F. (1999). Neurobiology of the structure of personality: Dopamine, facilitation of incentive motivation, and extraversion. Behavioural and Brain Sciences, 22(3), 491–517. https://doi.org/10.1017/S0140525X99002046
- Depue, R. A., & Fu, Y. (2013). On the nature of extraversion: Variation in conditioned contextual activation of dopamine-facilitated affective, cognitive, and motor processes.Frontiers in Human Neuroscience, 7, Article 288. https://doi.org/10.3389/fnhum.2013.00288
- Encyclopedia on Early Childhood Development. (2012). The impact of temperament on child development: Comments on Rothbart, Eisenberg, Kagan, and Schermerhorn and Bates. https://www.child-encyclopedia.com/temperament/according-experts/impact temperament-child-development-comments-rothbart-eisenberg kagan
- Fabio, A. D., & Corace, K. M. (2016). Personality and individual differences in psychology. Retrieved from PMC4873067, National Centre for Biotechnology Information. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4873067/
- Fleeson, W., Malanos, A. B., & Achille, N. M. (2002). An intraindividual process approach to the relationship between extraversion and positive affect: Is acting extraverted as “good” as being extraverted? Journal of Personality and Social Psychology, 83(6), 1409–1422. https://doi.org/10.1037/0022-3514.83.6.1409
- Hudson, N. W., & Fraley, R. C. (2015). Volitional personality trait change: Can people choose to change their personality traits? Journal of Personality and Social Psychology, 109(3), 490– 507. https://doi.org/10.1037/pspp0000021
- Jang, K. L., Livesley, W. J., & Vernon, P. A. (1996). Heritability of the Big Five personality dimensions and their facets: A twin study. Journal of Personality, 64(3), 577–591. https://doi.org/10.1111/j.1467-6494.1996.tb00522.x
- Roberts, B. W., & DelVecchio, W. F. (2000). The rank-order consistency of personality traits from childhood to old age: A quantitative review of longitudinal studies. Psychological Bulletin, 126(1), 3–25. https://doi.org/10.1037/0033-2909.126.1.3
- Vukasović, T., & Bratko, D. (2015). Heritability of personality: A meta-analysis of behaviour genetic studies. Psychological Bulletin, 141(4), 769–785. https://doi.org/10.1037/bul0000017
Leave feedback about this