Science Explains: introversion vs extroversion

When we think of introverts and extroverts, we think of the former being quiet and reserved and the latter talkative and outgoing. However, there is far more to it than this.

The two recharge in different ways: introverts recharge by spending time alone, but extroverts do so by socialising and being around other people. Extroverts enjoy group conversations, however, introverts enjoy talking one-on-one. In the same breath, those with extroverted personalities have larger quantities of friends with weaker bonds but introverts choose a few friends with whom they have closer relationships.

There aren’t only social differences between the two, but also with the way they deal with change. Extroverts easily accept it, whilst introverts struggle. Extroverts make decisions quickly, but introverts take the time before to reflect. Introverts enjoy a deep focus for a long time, but extroverts get distracted more easily.

The two recharge in different ways: introverts recharge by spending time alone, but extroverts do so by socialising and being around other people

However, the differences aren’t clear-cut. Most people are not one or the other but are instead a mixture of the two. People occupy a space on a scale from extroversion to ambiversion to introversion. So, you can be more introverted, but still inhabit aspects of extroversion. Dating back several decades, Hans Eysenck, a German psychologist, theorised that the behaviours of the two are down to differences in the speed and amount of the brain’s activity, (cortical arousal).

Introverts naturally have a higher level of activity, which means they may process more information per second. Therefore, putting them in a busy environment with a lot going on gives them too much to process and can overwhelm them. The lower levels of cortical arousal lead extroverts to seek out more stimulating environments.

You can be more introverted, but still inhabit aspects of extroversion

There are many other theories of extroversion and introversion. For example, extroverts gravitate towards some situations because they are more sensitive to rewards. Many studies over the years show clear psychological differences between introverts and extroverts. A 1999 study measured cerebral blood flow, discovering that introverts had more blood flow in frontal lobes and anterior thalamus. These are the parts of the brain which recall events, make plans and solve problems. Meanwhile, extroverts blood flow was concentrated in the area which interprets sensory data. This evidence compliments Jung’s beliefs that extroverts attention faces outwards and introverts faces inwards.

When lemon juice was dropped on the tongue, an experiment discovered that introverts produced more saliva than extroverts. Because introverts have a higher level of activity in the anterior of the brain, they don’t need the same amount of external stimuli as extroverts, who need more to produce the same results. In the same way, extroverts need more lemon juice to produce the same amount of saliva as introverts.

A 1999 study measured cerebral blood flow, discovering that introverts had more blood flow in frontal lobes and anterior thalamus

A study exploring distraction and focus saw introverts and extroverts placed in a white room with no windows or pictures. They were told to remain quiet – introverts did exactly that, but before long extroverts would whistle or drum their fingers. Some radical extroverts walked in circles.

Research also suggests that extroverts and introverts speak differently. Extroverts use language more abstractly, whilst introverts more concretely when describing things. One study asked participants to vocally describe different photos, with introverts using more precise language in their descriptions. Extroverts are consistently found to be happier than introverts. One theory is that this is because extroverts are more sensitive to rewarding social situations whilst other research suggests it’s because they engage in more social activities. Some theories believe it’s because they have better mood-regulating abilities than introverts or perhaps because they hold on to good memories.

Extroverts are consistently found to be happier than introverts

However, it’s unclear whether they are happier or whether they’re more open to declaring their feelings, which begs the question: how do you measure happiness?