The science of personality

The science of personality: are we stuck with who we are?

Psychology has investigated extensively personality: how many traits, how many profiles, how to measure them, how to predict them, are any of them defining a disorder or a disease, and where does personality come from? Is that something we are just born with? Is that coming from our parents, our culture, our experiences?

A numbers’ game

Personality traits take place on several continuums or factors. But the number of factors has been varying and debated among psychologists. Through reviews of multiple studies and factor analysis, a consensus grows in favor of five main factors describing all possible personalities. The Big Five personality traits are largely considered to be the most scientifically robust way to describe personality differences. Most personality research is based on this model. Each of the five traits is on a continuum, from low to high:

  • Openness – how much we are open to new ideas and experiences
  • Conscientiousness – how much goal-directed, persistent, and organized we are
  • Extraversion – how much energized we are by the outside world
  • Agreeableness – how much we puts others’ interests and needs ahead of our own
  • Neuroticism – how sensitive we are to stress and negative emotional triggers

Go ahead and test yourself for free here, it’s very insightful!

These five factors have been found relevant cross-culturally, and therefore universally. For this reason, these five factors are perceived as ‘biologically based’, and considered fixed and sustaining throughout our lives. But is that truly so?

Nature: the influence of biology

The influence of biology on personality, Photo by The Blowup on Unsplash

Interestingly, personality traits are sometimes found altered by brain damage, implying the influence of biology on personality. A longitudinal study was performed on 114 patients with brain injury, compared to thousands of people with brain impairment (due to some other medical conditions), and compared to thousands of healthy people (Leonhardt et al., 2016). These groups were tested in 2005, and again in 2009, using the Big Five dimensions. Those with a brain injury and those with other brain impairment were found to have modifications to their Big Five personality. Those with a brain injury had a significant drop in Extraversion and Conscientiousness, and those with other brain impairments also had a decline in Extraversion. Simply put, injury or impairment appears to impact sociability and self-discipline. This study resonated with evidence from other studies and showed that biology does indeed play a role in personality.

Does this mean that personality is biologically determined? Well, it’s not, or at least not entirely. Biology does have an influence, but it doesn’t account for individual differences across humanity. In fact, some psychologists have argued that the Big Five are rather descriptive than explanatory, meaning that these factors don’t really explain the reasons for human behaviors (John and Srivastava, 1999). But then, if biology is not the only ingredient for personality, what else is?

Nurture: the influence of trauma

The influence of trauma on personality, Photo by Rod Long on Unsplash

Childhood emotional trauma and neglect are also found to influence personality. A study (de Carvalho et al., 2015) analyzed survey data from 8’114 volunteers recruited online. The survey included another type of personality inventory, called the Temperament and Character Inventory (TCI). It assesses four temperaments (reward dependence, novelty-seeking, persistence, and harm avoidance), and three character dimensions (cooperativeness, self-directedness, and self-transcendence) as well as a Childhood Trauma Questionnaire (available in PDF on this link). It was found that people who have experienced emotional abuse and neglect tend to avoid harm, struggle to regulate and adapt their behaviors, and struggle to identify with and accept others. Those who had experienced emotional neglect were also less dependent on reward and less persistent. Novelty seeking was generally high for all those who had suffered physical or emotional abuse. Understandably, after experiencing a difficult childhood, people will adopt certain personality traits as a sort of survival mechanism. So it’s not just biology then.

Powerless or powerful?

Our personality at the mercy of brain impairment or childhood trauma? Although it’s partially correct, it also gives a depressing impression that we go through a passive experience of life. Maybe you can even think of someone in your life who has changed after negative events: for instance, they were betrayed and hurt, now they are bitter and keep people at a distance. It may seem we are powerless in changing our personality, it just happens to us because of forces we can’t control…

Or maybe not… Another longitudinal experiment gives us an empowering perspective. It took place on a 16-week period, with 135 participants aged from 18 to 27 years (Hudson and Fraley, 2015). Those who wished to increase certain Big Five personality traits were able to demonstrate an actual increase. This study also found an efficient intervention, which helped participants achieve the trait changes they aimed for. The results suggest that “people can change their personality traits, merely because they desire to do so”. Practical tools and intentions can increase and even double the amount of personality trait change:

ToolsWhat could it look like?
changing our patterns of thoughts, feelings, and behaviorsjournaling, setting intentions, and paying attention are great places to start
developing concrete and specific plans/actions to get out of the comfort zone and in the direction of the personality trait change we aim for “sign up for skydiving on Tuesday”
planning “if… then” intentions “if skydiving is fully booked, then I will sign up for paragliding”

What does it tell us?

Well, that personality is not determined by biology alone, but also by experience and importantly by choice! This means that unless we have some kind of injury or impairment, we are not stuck with who we are. We are not limited and damaged by past traumas. We can grow, we can change, we can decide who we want to be. And maybe we don’t need to change our personality traits, but consciously and proactively choose to embrace them. And that’s empowerment!

How do you feel about your personality traits? Would you change anything about who you are?


  • Big Five Personality Test
  • de Carvalho HW, Pereira R, Frozi J, Bisol LW, Ottoni GL and Lara DR (2015) ‘Childhood trauma is associated with maladaptive personality traits’, Child Abuse & Neglect, Vol. 44, pp. 18-25 [Online]. Available at
  • Hudson NW and Fraley RC (2015) ‘Volitional Personality Trait Change: Can People Choose to Change Their Personality Traits?’, Journal of Personality and Social Psychology, Vol. 109, No. 3, pp. 490-507 [Online]. Available at
  • John OP and Srivastava S (1999) ‘The Big-Five trait taxonomy: History, measurement, and theoretical perspectives’, in Pervin, L. A. and John, O. P. (eds.) Handbook of personality: Theory and research [Online], Guilford Press, New York. Available at
  • Leonhardt A, Schmukle SC and Exner C (2016) ‘Evidence of Big-Five personality changes following acquired brain injury from a prospective longitudinal investigation’, Journal of Psychosomatic Research, Vol. 82, pp. 17-23 [Online]. Available at

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