“I’ve had success in these fields, but every time I go out there, I have to talk to myself, almost a version of the Stuart Smalley thing,” Mr. Bess said, referring to the comical character created by Al Franken on “Saturday Night Live” who intoned in the mirror, “I’m good enough, I’m smart enough, and doggone it, people like me.”

Mr. Bess sometimes hid his discomfiture at a party by having a fake conversation on his cellphone. Drinking helped (a solution known as “liquid extroversion”), but now he substitutes less-damaging forms of courage. “It’s so annoying, the amount of things I have to do to be O.K. socially,” he said. “I meditate, write in a journal, run, exercise and just try to get out of my own head.”

The terms “shy” and “introvert” are used almost interchangeably and without distinction in the common parlance. “Psychologists debate about the overlap,” said Susan Cain, author of the recent book “Quiet: The Power of Introverts in a World That Can’t Stop Talking,” which extols the power of those who prefer listening to speaking, or reading to socializing. “Shyness is fear of social judgment, a consuming worry about how people view you. Introversion is more about a preference for environments that are less stimulating: someone who’d rather have a glass of wine with a close friend than go to a cocktail party.”

Shyness exists on a continuum, from mild to paralyzing, according to Christopher Lane, a professor at Northwestern University and author of the book “Shyness: How Normal Behavior Became a Sickness.”

“I am firmly of the belief that shyness and introversion are acquired, not passed on genetically,” he said. “They’re behavioral traits that people experience in early life, becoming part of their personality. It’s only recently that we have begun to think of that behavior as a problem. In the ’40s, ’50s and ’60s, there was far less expectation that people would be loquacious, more emphasis on being reserved.”