Human beings are social animals. Some of us—the extroverts—need a lot of contact with humans. One extrovert I talked to said that he doesn't feel he exists unless he is with another person or in a group. He also confided that interpersonal exchanges energize him. Another extrovert told me that he whiles away time whenever he is alone until he is back among friends or colleagues. He works as a salesman and sometimes talks to a hundred people daily. He loves it. Others of us—introverts—prefer less interaction with others. I definitely fall into this category. In contrast to my extroverted