Turhan Canli has an odd photo collection. It includes several shots of people's faces. He has photos of the words "death," "happiness" and others printed in various colors. He also has images of fanged snakes and snarling dogs, babies and white supremacists. Canli, a psychologist at the State University of New York at Stony Brook, recently showed several of the pictures to Robert Sheiman, 22, a theater manager from New Haven, Connecticut. Before viewing them Sheiman inserted himself into an fMRI scanner, and as the photos flashed up one by one, he indicated his reaction--positive, negative or neutral--by pressing buttons. The type of image that came up most often was a person's face along with a word. Sometimes the connection between face and word was vaguely comical--such as happy face along with the word "stool"--and at other times disturbing, the person crying and "happiness." After an hour under the scanner, "I came out of it shaking," says Sheiman. "It wasn't difficult, but it was overwhelming."
Canli thinks that the way Sheiman and others respond emotionally to these peculiar word-image combinations--and specifically what happens inside their brains--can tell a lot about what kind of people they are. "Certain types of people can't help but notice the emotional meaning of certain words," he says. Neurotic personalities tend to focus their attention on ugly or repellent images, their brains lighting up at pictures of rotting food or mutilated bodies. Extroverts, on the other hand, prefer pleasurable objects such as sunsets or giggling babies. For years Canli has been putting test subjects like Sheiman under the scanners and cataloging the personality types. "Can you use a brain scan to read personality?" he says. "Of course you can."
Anybody who's ever interviewed a prospective job applicant knows how important the ability to judge personality can be, and how difficult it is to do well. Personality--an ambiguous, amorphous and subjective concept--has always resisted quantitative measurement. But lately scientists like Canli have begun to zero in on the mechanisms of human physiology that bear on the perennial problem: what makes some people better suited to a particular task than others? For the first time, science may be able to offer useful insights for employers by drawing accurate conclusions about deep-rooted character traits. "Such a strong reaction between brain function and personality surprised everybody," says Martha Farah, professor of psychology at the University of Pennsylvania. "It showed that personality differences correspond to something very basic about the different ways people's brains process information."
Now would be a good time to put some science into the ancient art of job interviewing. In a global economy driven by skilled workers, a great deal is riding on whether companies and other institutions can pick out candidates with the most potential. For high-profile jobs, says Ivan Robertson of Robertson Cooper, a business psychology company, "the value of someone performing a bit better or a bit worse could be very significant in monetary terms." The Future Foundation, a consulting firm, and U.K. psychometric-testing firm SHL found in a study last year that poorly performing employees cost their employers more than $22 billion in the United Kingdom and more than $100 billion in the United States. Deciding who's best suited to being a doctor, cop, air-traffic controller or priest may be worth even more. Judges ruling on child-custody cases often face thorny decisions over who's more fit to be a parent.
Because the stakes are higher, demand for personality tests has skyrocketed in recent years. Big corporations started testing in earnest more than a decade ago for hiring, but many have taken to using such tests for internal promotions as well. And small firms, governments, schools and other institutions are getting into the act. Testing is a $400 million industry in the United States and is growing at 8 percent a year. The problem, though, is that current quizzes are often little better at predicting than astrologers. "They can be very misleading," says Dan P. McAdams, a psychologist at Northwestern University in Chicago.
The most popular tests tend to be questionnaires based on generalized notions of different personality types. In the most widely used one, the Myers-Briggs Type Indicator, test subjects answer questions about their own tendencies and behaviors and get classified along four opposing scales--introversion and extroversion, sensing and intuition, thinking and feeling, judging and perceiving. Then each person is bracketed within a four-letter category. "ESTJs" for instance--extroverted, sensing, thinking, judging types--make natural leaders; they direct action and organize projects logically. "ESFPs" are fun-loving party people who might neglect task-oriented work, preferring projects that promise more interaction with colleagues. Today 89 of the companies in the Fortune 100, as well as thousands of others, use Myers-Briggs in hiring and promoting. Although experts concede that the test seems to capture valid aspects of personality, they say it's far too blunt to be of practical use. "It has vastly oversimplified personality, making it sound like people are walking 'types'," says McAdams. "Most people are blends."
The Minnesota Multiphasic Personality Inventory, or MMPI, is widely used to ferret out substance abuse and other symptoms of social maladjustment. Although psychologists say the test has some value, it tends to flag otherwise normal test takers as pathological. Still, 60 percent of police departments in the United States use the test to evaluate prospective officers, and personality tests based on its questions are taken by job applicants in industries from banking to retail. The test has also been translated into more than 100 languages, including Russian, Chinese and Arabic. Annie Murphy Paul, author of "The Cult of Personality," thinks the MMPI and other tests are marketed too aggressively to businesses, --with alarmist ads that play on their fears. "There's a sense that it can help you screen out people who are dangerous and dishonest," she says. "But they're taking a very concrete and specific approach to solving a very ambiguous and amorphous problem."
Some tests are even worse. The Rorschach inkblot method, in which subjects are asked what they see in abstract shapes, is "an embarrassment to psychology," says McAdams. And yet, according to 2001 report, the method was used in 1999 in one third of emotional-injury lawsuits in the United States and by 44 percent of psychologists who conduct child-custody evaluations. Like the MMPI, the Rorschach test may also find symptoms of mental illness where they don't exist.
A new, more accurate generation of personality tests has recently hit the market. These aren't the product of brain scans and other fancy new technologies, but neither are they based on grand sweeping theories. Instead they're derived from empirical studies about how certain types of people behave in certain situations. One such test is the NEO (Neuroticism, Extroversion and Openness) Personality Inventory, a subtler model than Myers-Briggs that measures five main traits: extroversion, neuroticism, agreeableness, conscientiousness and openness. Unlike the MMPI and Rorschach tests, it was designed to measure normal personalities.
Rather than trying to take in the full sweep of human personality, this new breed of test concentrates on narrower tasks, such as whether a candidate would make a good cop or an effective retail-store manager. One of the more promising ones is the OPQ--Occupational Personality Questionnaire, which measures 32 factors relevant to work roles, like leadership skills, sociability, and the ability to persuade others. The norms against which testing firm SHL assesses responses are also created on a country-by-country basis, which means answers given by a Lithuanian management trainee to a question such as "I like to take charge" can be compared with those given by Lithuanians of a similar background.
The test is showing some impressive results. When London media executive Phil Georgiadis was recruited for a new venture by Christine Walker, a high-flyer renowned in the industry as vivacious and tough, he wanted to know more about her before deciding. "I knew her by reputation and had some fears and concerns about being her partner," he says. So at his request Walker visited testing firm SRS and took a lengthy quiz, assessing her on 24 different traits, from her levels of trust and insecurity, to her emotional stability and breadth of thinking, to her need for prestige, support and communication. "The fundamental things I found out were that she's not a one-woman band and that she wanted to share. That was all I needed to know," says Georgiadis, who took the job.
SHL, working with U.S. firm Neiman Marcus, increased sales per associate by 42 percent and reduced staff turnover by 18 percent by clearly identifying the characteristics needed for the job of sales associate, and designing a test to select employees who showed those traits. "People like to be successful, and they stay when they are," says John Bateson, chief executive of SHL. In an earlier job managing a media firm, Georgiadis found SRS's 24-trait model revealed surprising insights into his employees. "There might be someone who talked a good game and looked like an agent of change," he said, "but [the test showed] that beneath the surface he's the most conservative person here."
As businesses grow to appreciate such tools, scientists like Canli are digging even deeper, honing in on genetic and neural predictors of personality. "If I know what the conditions are under which I see [a certain] activation pattern I can make a good prediction as to what this person's personality traits are," Canli says. His brain scans have shown that people differ profoundly in their brain wiring, even down to primitive structures--like the amygdala, the seat of emotions--that humans share with squirrels and lizards.
Scientists are also exploring the role of genes in setting the range of personality traits a person can develop. "There are certain genes that we all share but which differ in subtle ways from one person to another and which have been associated with neuroticism, novelty seeking and other traits," says Canli. For instance, two different forms of one gene regulate serotonin, a neurotransmitter associated with mood and emotional stability. One is short and one long, and every individual has two copies of the gene, one from each parent. Those with two short copies are more likely to be neurotic, anxious and risk averse. Swedish psychologist Eva Longato-Stadler found that criminals with personality disorders had lower than normal levels of an enzyme called monoamine oxidase, which affects the ability of the brain to use or synthesize serotonin. She thinks that these low levels contribute to an accelerated breakdown of the hormone norepinephrine, which is involved in regulating the body's response to stress--its "fight or flight" response. Studies show that, in people with personality disorders, a lack of norepinephrine tends to lead to criminal behavior.
The potential power of brain scans and genetic testing to reveal personality raises tricky questions. Will courts someday use a cotton-swab test to help determine which parent gets custody of a child? Will a company pick its next CEO by probing his or her brain? "We're heading in that direction," says Paul. Would it be fair to the job applicant if a personality test also revealed a brain tumor? Or a gene associated with pathological behavior? Whether or not these ethical questions get resolved, businesses are certain to use more accurate tests to predict not only whom to hire, but how long they'll stay, what they'll need to work on and how profitable they'll be. Personality is "the supreme realization of the innate idiosyncrasy of a living being," said Carl Jung, and "an act of high courage flung in the face of life." Science is giving us new ways of reaching into these depths, capturing our elusive, shadowy selves.