Is Walter Mitty an introvert or an extravert?

Walter Mitty is an introvert. He might be said to be a typical James Thurber character. Other examples of such characters, all of which can be found in the best collection of Thurber’s short pieces, The Thurber Carnival, are Mr. Martin in “The Catbird Seat,” the unnamed protagonist of “One is a Wanderer,” Samuel O. Bruhl, the antihero in “The Remarkable Case of Mr. Bruhl,” and Thurber himself in “A Note at the End.” And there are many typical James Thurber characters in the generous selection of cartoons included in The Thurber Carnival, for James Thurber was at least as famous for his drawings as for his stories, essays, and miscellaneous humor pieces.
It was the distinguished psychoanalyst Carl Jung who coined the terms “introvert” and “extravert” in his book Psychological Types (1921). According to Jung:
The introvert is not forthcoming, he is as though in continual retreat before the object. He holds aloof from external happenings, does not join in, has a distinct dislike of society as soon as he finds himself among too many people. In a large gathering he feels lonely and lost. The more crowded it is, the greater becomes his resistance. He is not in the least “with it,” and has no love of enthusiastic get-togethers. He is not a good mixer. What he does, he does in his own way, barricading himself against influences from outside. He is apt to appear awkward, often seeming inhibited, and it frequently happens that, by a certain brusqueness of manner, or by his glum unapproachability, or some kind of malapropism, he causes unwitting offence to people. His better qualities he keeps to himself, and generally does everything he can to dissemble them. He is easily mistrustful, self-willed, often suffers from inferiority feelings and for this reason is also envious. His apprehensiveness of the object is not due to fear, but to the fact that it seems to him negative, demanding, overpowering or even menacing.
The introvert sees everything that is in any way valuable to him in the subject; the extravert sees it in the object. This dependence on the object seems to the introvert a mark of the greatest inferiority, while to the extravert the preoccupation with the subject seems nothing but infantile autoeroticism. So it is not surprising that the two types often come into conflict. This does not, however, prevent most men from marrying women of the opposite type. Such marriages are very valuable as psychological symbioses so long as the partners do not attempt a mutual “psychological” understanding.
Examples of how Walter Mitty “sees everything that is in any way valuable to him in the subject” can be seen in all the episodes in which he is fantasizing about doing heroic or noble deeds. They are all triggered by objective reality and then translated into subjective experiences. For example, his wife tells him he should see Dr. Renshaw, and he quickly begins imagining that he himself is a distinguished surgeon. Mitty pictures their family doctor in his fantasy as “haggard and distraught.”
“Hello, Mitty,” he said. “We’re having the devil’s own time with McMillan, the millionaire banker and close personal friend of Roosevelt. Obstreosis of the ductal tract. Tertiary. Wish you’d take a look at him.”
As another example, Walter Mitty is driving to town and notes that it looks like rain, and he becomes Commander Mitty piloting a hydroplane through hurricane weather. The object becomes subjective. Jung states in Psychological Types that modern art has become more and more subjective. In painting many artists still use the object but do all sorts of weird things with it in order to express their own thoughts and feelings. Pablo Picasso is a prime example in his expressionist paintings such as the famous “Guernica.” Mitty is like Picasso in being more interested in his own thoughts, feelings, impressions and reactions than in the objective world in which he has to park cars and buy puppy biscuits.
Where Jung writes “This does not, however, prevent most men from marrying women of the opposite type,” he seems to be saying that most introverted men marry women of the opposite type. Or else he only means that introverted men are usually content with being married to extraverted women. At least we see many marriages in which the husband is quiet and introspective while his wife handles all the domestic and social arrangements. She may even tell her husband what suit to wear to work and what necktie should go with it. Jung calls this "psychological symbiosis." If the Mittys have a “symbiotic” relationship, what does Walter contribute? He is probably the one who earns the income—although it is his wife who spends most of it. He is the only one who can drive a car. Her concern about her husband may be largely a matter of dependence. Even her social life would be crimped if she were a widow or, worse yet, a divorcee rather than part of a couple. And this would be a serious matter for an extravert.