You can identify extroverts immediately after birth. Some babies orient toward a sudden noise while others shy away. The former are future extroverts.
As Susan Cain reveals in Quiet: The Power of Introverts in a World That Can’t Stop Talking, extroverts prefer a higher arousal level and are, thus, more likely to do arousing things like drive fast, turn the music up loud, and attend nightclubs.
We function best when we are at our optimal level of arousal. For instance, introverts perform significantly better in lecture-based classes, which are not highly arousing. However, this is not true of more stimulating lab-based classes.
Interestingly, some substances can influence this by altering our arousal level. Alcohol, a depressant, lowers arousal while caffeine, a stimulant, increases arousal. In one study, extroverts performed a task better after ingesting two cups of coffee while introverts performed worse. This effect was magnified when the task was done under time pressure because that increased arousal even further, moving the extroverts closer to optimal and the introverts further away. Beer would have the opposite effect.
At what level of arousal do you function best?
NOTE: Most of us are somewhere in the middle, or “ambiverts”. For these folks water may be the best beverage choice 😉