Are you the kind of person who forgets a name the minute you are introduced to someone new? You shake hands, nod politely and go blank?

If so, you could be shy -- not senile -- and you're suffering the consequences.

Shy people often "don't tune in appropriately" in social situations, says psychologist Philip G. Zimbardo, director of the Stanford (University) Shyness Clinic in California. In this case, instead of giving "undivided attention" to the stranger, they may -- because of anxiety -- "be rehearsing their own names."

The shy are apt to be more concerned about the possibility of their "being evaluated" than greeting the stranger. "If you're thinking about yourself," says Zimbardo, "you're going to have less brain power."

Such memory impairment is only one of a multitude of disadvantages that hinder shy people trying to make their way in a world of aggressive movers and shakers. Zimbardo calls shyness "a self-imposed loss of basic freedoms" -- among them "freedom of speech, association and acting in one's own best interests."

In the extreme, shyness, he says, can lead to "isolation" with an absence of love and respect: "the human connection." This increases one's vulnerability to "depression, suicidal tendencies, paranoia and to the worst effects of stress." Leading even, says Zimbardo, to "the bottled-up rage in the good, shy, pussycat boy who makes headlines as a mass murderer -- the first naughty deed of his life."

One irony, he notes, is that though shy people "are afraid to be with people," they are also unhappy in their solitude. "The issue in isolation is whether you choose it or see it imposed."

From his studies over the past decade, Zimbardo concludes that about 40 percent of the American population "thinks of themselves as shy." And most of them see their condition as "undesirable and a serious problem that interferes with their lives."

Shy people, he says, "don't initiate, they don't complain, they don't demand their fair share, they don't stand up for their rights." In school they get mowed over by classmates who snatch the extracurricular plums, and on the job by office mates who capture the pay raises and promotions.

Before his shyness studies, Zimbardo noticed students in his psychology classes who "would never say a word. I first thought they were unprepared, unmotivated and maybe not so bright." But some of them earned 'A's. "They were prepared, interested, bright -- and inhibited.

"That's one of the dangers when you don't speak up. It allows people to make these assumptions.

"If you are shy and one of the beautiful people, you're almost in double jeopardy." People who don't recognize your shyness -- "you seem to have so much going for you" -- see your hesitancy as "condescension, aloofness, hostility."

Zimbardo makes what he calls "a critical distinction" between the chronically shy and the "situational" shy. "The chronically shy cripples himself by saying 'the shyness is in me,'" -- feeling inadequate about what he or she sees as personal defects.

"The situational shy says something is wrong with the world." If, for example, he is shy on blind dates, then "blind dates are bad." Zimbardo sees this form as a psychologically healthier attitude.

Another example of situational shyness: As an adolescent, "You imagine girls are tuned into your sexual thoughts about them and you begin to feel embarrassed."

Shyness, Zimbardo believes, is not something you are born with, but "rooted in early childhood experiences." Among possible causes:

* Difficulties in school.

* Unfavorable comparisons with older siblings, relatives or peers.

* Loss of usual social supports that "results from frequent family moves out of the neighborhood, or from sudden changes in social bonding due to divorce, death, going off to a new school."

* Poor parental models.

* Lack of experience in social settings (living in an isolated area or in a restrictive household).

You can, Zimbardo is eager to point out, overcome shyness if you want to, or at least minimize its impact on your life. Parents, he and co-author Shirley Radl write in a new book, A Parent's Guide to The Shy Child (McGraw Hill, $11.95, 261 pages), can take steps to prevent shyness in their children.

"You can," he says. "I have."

When his now 6-year-old daughter Zara was born, "I just decided I ought to be able to do something that would prevent this child from becoming shy." Her older brother grew up as a shy child before Zimbardo began his studies.

Incorporating in Zara's upbringing what he had learned, he says, has made her a child "who not only is not shy, but is highly esteemed by other children. They seek her out. She's responsive. Others enjoy being with her.

"These are desirable traits parents can teach if they are willing to take the effort and put out the time."

Parents, he advises, ought to think in terms of prevention. "An ounce of prevention clearly is worth more than a ton of therapists."

Was he ever shy?

"Never. No. I come from a large Italian family. I was the first born. My mother said, 'You are in charge of the family. Make them comfortable.'

"Always being concerned about others," He says, "That's the opposite of being shy." Zinbardo, 48, became a shyness expert almost by accident. Two students he had asked to track down information on the subject for a different study returned from the library to report, "There's nothing there."

The led to the research that continues after almost 10 years and formation of the Standford Shyness Clinic, which, he says has had excellent success in helping the timid in the Palo Alto area.

At times along the way when he considered abandoning his research, people would appeal to him: "'Help! I'm shy.' 'My brother's shy.' 'My father's shy. People were sending me pictures of beautiful children 'without a friend in the world.'"

At the clinic, where the average age of patients is the mid-30s, therapists work to get the chronically shy to "change one or more ways in which shyness affects their lives negatively," such as the inability to have a close relationship, or the fear of speaking in public. "We start with a small step that is relatively safe. If it is fear of talking, they call the telephone operator for the time. Then they go on to a frightening thing -- the line in the food market, where they speak to the cashier."

Similarly, if dinner parties are a problem, he advises, "be the first to initiate the conversation. Shy people often lay back and let others take the initiative, and someone else brings up a subject you know nothing about." It is a matter, he says, of "practice."

A major element in shyness he says, is lack of self-esteem. A sense of self-worth is "at the key of our identity. It's the ratio of good and bad things you say about yourself and believe." A shy person "says to himself things you wouldn't say to you worst enemy. He [or she] rarely says positive things, even when they are deserved."

To build self-esteem, Zimbardo urges parents to give their children "love unconditionally, without the necessity of the child becoming a performer." Avoid comments that could be interpreted as: "I love you if you make 'A's." A child hearing that repeatedly "grows up thinking 'I'm only as good as my performance.' he or she senses that love can be taken away with failure."

When children are told, "I love you just the same," they "are not afraid to fail."

"Inadequate social skills" are another factor. "knowing what to do and when and how is something we all take for granted." Children "need instruction, models, practice with feedback. In school there are no classes in private conversation where children learn the art of relating."

One big concern for the future: "I see so many social forces working to increase shyness. It's almost futile to try to overcome it.

"The average child spends three to four hours a day watching TV. That's inducing passivity. They don't learn to negotiate.

"The next stage is when children are more content to play video games where the opponent is a micro chip and not another person. My sense is that scenario is very bleak unless parents say, 'I want my child to be a social animal.'"