I disagree with the idea that extroverts thrive on a high level of arousal. Although extroverts may be able to tolerate a higher level of arousal than introverts, high levels of arousal tend not to have a positive influence on behavior no matter what the personality type. Studies show that both high and low arousal limit one's ability to perform tasks (Emotion, P371). In fact, high arousal makes it less likely one will be able to concentrate on what he or she is attempting to do (op. cit.).
A very strong relationship exists between arousal and behavior. Neither high nor low arousal has a positive on behavior. In addition, when these extremes are paired with heightened emotional states, the combination makes positive action nearly impossible (P371). Extroverts are more likely to have higher levels of arousal then introverts. For an introvert, fear is more likely to cause arousal and therefore, they are more likely to flee situations that cause it (op. cit.). This idea explains why introverts remain less comfortable in social situations then their counterparts. By contrast, extroverts experience higher arousal in enjoyable situations and are likely to remain happy (P369) and are more likely to overcome fearful situations than their introverted counterparts.