The world is full of right-handed scissors, ladles, school desks, notebooks, watches, even playing cards. For the practicing left-hander—one person out of 10—these nuisances are ubiquitous but manageable. Now an educational psychologist in San Luis Obispo has theorized that another 12 percent of the population are born left-handed but don't know it, suffer anxiety as a result and are thus more susceptible to ulcers and heart trouble.

Author of the alarming theory is Dean Trembly, 71, a retired faculty member of California Polytechnic's testing and counseling center. His research into "handedness-related problems" was inspired by his study of young polio victims at the University of Illinois in 1961. The group included an abnormal number of "crossed-dominants"—people who were naturally left-handed but used their right hands for most tasks. That finding suggested two hypotheses to Trembly. One was that crossed-dominant children had unusually high nervous energy, possibly played harder and the resulting fatigue could have been a factor in catching polio. The second was that the nervous tension itself "increased their vulnerability" to the disease.

Trembly believes that one-fourth of all humans have dominant left hands, eyes and feet, a condition that is called left-sidedness. One reliable way to determine this is the eye dominance test (preceding page).

As a counselor for 15 years at Cal Poly, Trembly says, "I talked with individuals about anything that bothered them, from their love life to career guidance. If I saw a student with fingernails chewed down, nine times out of 10 the student was left-handed but acted right-handed."

Though there has been no independent verification of Trembly's stress theory, he says he found remarkable statistical correlation in random groups of ulcer patients (39 of 121 were crossed-dominants) and heart patients (37 of 93). He speculates that the subconscious strain of adjusting to crossed-dominance damages the nervous system, making illness more likely. Trembly plans to study lung cancer patients on the theory that many crossed-dominants will be found among them—victims of heavy smoking because of nervousness.

Trembly has his critics. Says Dr. Richard Trafton, a Boston psychologist who is also studying crossed-dominance: "It's true that a large proportion of people who have emotional and medical problems also suffer from crossed-dominance, but it does not necessarily cause those problems. Both are probably results of another cause—heredity, or neurological development, or being dropped on the head as a child."

Trembly is a Columbus, Ind. native with degrees from Colorado College in music and psychology. While working for a career guidance firm in Fort Worth he used the eye-dominance test on students and noticed a relationship between crossed-dominance, nervousness and reading troubles. It sparked his interest. He quit in 1955 and got his Ph.D. at Illinois.

Himself right-handed, Trembly says children should be tested for eye-dominance between 2—when handedness establishes itself—and 6, after which it is difficult to change. However, even adults can liberate their left hands, he says, if they are willing to work at it.

In the beginning, Trembly says, crossed-dominants should try simple chores such as brushing their teeth with the left hand, "to see themselves as left-sided." "Leave handwriting until the very last," he advises, "then start with your signature."

The treatment doesn't always work. "It's like alcoholism," Trembly sighs. "You have to decide you want to quit before you can."

(Faber and photographer Michael Alexander, who took the pictures for this article, tested left-eyed and write left-handed. However, Faber knits, eats and plays tennis with her right hand, and Alexander eats and sights his cameras with his right.)