My best friend Jeannie is an extrovert -- sociable, positive, and friendly. She has long, personal conversations with people she meets on walks, with her hairdresser, her accountant, her nurses, and doctors.
As a result, she amasses huge amounts of useful information as well as having an interesting life. She is my "go-to" person whenever I need a dog-sitter, a plumber, or a place where I can find juniper berries for my sauerbraten.
I am an introvert, happiest when I am alone, reading a book, or writing this column.
Since American society places such high value on extroverts, I was delighted to find a new book celebrating introverts like me, "Quiet: The Power of Introverts in a World That Can't Stop Talking," by Susan Cain.
"At least one-third of the people we know are introverts," she writes. "They are the ones who prefer listening to speaking, reading to partying; who innovate and create but dislike self-promotion; who favor working on their own over brainstorming in teams. It is to introverts that we owe many of the great contributions to society."
Without introverts we would not have:
• "Harry Potter"
• The theories of gravity and relativity
• "Peter Pan," "The Cat in the Hat," and "Alice in Wonderland"
Sure, the introverted genius who invents new technology in his garage is admired, but Americans typically value those with people skills, who work well in teams, who are outgoing and social.
Extroverts and introverts differ in a host of ways. Extroverts exercise more, function well without sleep, place big bets, commit adultery more, and get energy from being with other people.
Introverts are more careful and analytic. They learn more from mistakes, are more thoughtful, slower to make decisions, and have a greater ability to wait for large, distant rewards than to rake in smaller rewards right now.
These personality types even decorate their offices in different ways. Extroverts are more apt to put candy on their desks, keep their doors open, and keep a lot of chairs nearby. Introverts decorate a lot less and organize their offices in ways that do not encourage people to walk in and chat.
Extroverts also like clothes that make a statement while introverts prefer practical, comfortable clothes. (Someone once told me that I dressed like a file cabinet.)
Extroverts enjoy stimulation. About 50 percent of extroverts play music while they are working, compared with 25 percent of introverts, find Daoussis and McKelvie in an experiment reported in Perceptual and Motor Skills.
Introverts find music and background noise distracting. Introverts did worse on a memory task, Daoussis and McKelvie found, while listening to music while extroverts did not.
Introversion and Extroversion are the north and south poles of a personality trait recognized across cultures. The trait is highly genetic, with roughly 40 percent determined by biology.
Extroversion is far more common in America than in Asia and Africa. This makes sense -- immigrants would be more likely to be in search of novelty and excitement and pass this trait onto their children.
Alaska, however, has an exceptionally high population of introverts, perhaps because so many loners have migrated here. The Midwestern states, like Illinois, have the highest proportion of extroverts.
The animal kingdom also has introverts and extroverts, find evolutionary biologists.
David Sloan Wilson, for example, believes that the two types have different survival strategies which help them thrive in different circumstances.
Animal introverts scan the environment in fear of predators; like human introverts, they are very sensitive to threats. Animal extroverts roam and explore. They do better when food is scarce.
If you are an introvert, says Susan Cain, find a niche where you can work in the lamplight rather than in the spotlight. Remember that introverts can learn to turn on when they have to do something frightening, like giving a speech.
Introverts aren't shy. They just don't like high levels of stimulation. We need extroverts like Jeannie and introverts like me.
Judith Kleinfeld is professor of psychology emeritus at the University of Alaska Fairbanks.