We are how we act, and the research of many faculty members of Princeton's Department of Psychology focuses on why people behave in certain ways, or how their reactions to the world around them affect their ability to acquire and retain knowledge. In the following profiles, writer Deborah Kaple explores the work of five professors on a range of topics: delusions about rational behavior, alcohol abuse among college students, sexual license among teenagers, the link between stress and learning, and aural and visual perception.

ACTING RATIONALLY
Our species's name, Homo sapiens-"thinking man"-implies that we are rational creatures. But are we? Associate Professor Eldar Shafir, a specialist in judgment, decision making, inference, and reasoning, thinks not. His work has demonstrated our basic irrationality in countless ways, including how physicians make decisions that may not always be in the best interests of their patients.
There is a "tension," says Shafir, between what psychologists have learned in the laboratory about decision-making and assumptions about it held by other social scientists. Indeed, this probably understatesthe longstanding debate between psychologists and economists, whose research assumes that people making decisions rationally maximize their outcomes. "In the last 15 or 20 years," Shafir asserts, "psychologists have carried out study after study, clearly demonstrating that the way people behave systematically conflicts with the classical theories of rational behavior."
Like economists, most of us assume that a person facing a set of options has some method of evaluating them, then chooses the best alternative. Shafir belongs to a group of psychologists who are testing this intuitive definition of rational behavior in decisionmaking. In research done on consumers, Princeton undergraduates, and physicians, he has found that few people make decisions in any way that approximates rational behavior. Says Shafir, "It's often assumed that when people look at a set of options, they have some way of evaluating each, that they assign some value to each, and then choose the one that rates the highest. As it turns out, people have a very hard time assigning systematic values to things. Instead, a person is more likely to arrive intuitively at a decision that 'looks right' in that particular context." The process may have a kind of logic to it, Shafir says, but it is a logic that often "leads to systematic failures and errors."
As a precursor to a major study on decisionmaking among physicians, Shafir and his colleagues conducted a pilot study on decisionmaking among two groups of Princeton undergraduates. The researchers asked students to fill out a questionnaire, for which they were promised $1.50. When the students actually completed the questionnaire, they were offered the choice of taking either the money or a nice "Zebra" pen, worth about $2 at the University Store. About half the subjects in the first group took the pen.
The second group was offered a more complex choice: the money, as promised, the "Zebra" pen, or a package of two less-expensive pens. This time, most students decided to take the money. The addition of just one more option increased the conflict inherent in the decision. Money or pen? One nice metal pen or two cheaper plastic pens? "The conflict inherent to the choice between pens compelled most students to forgo thinking about it and simply take the money," says Shafir.
These results mirrored the larger study on medical decision-making, published in the Journal of the American Medical Association, which Shafir and his collaborators carried out among physicians in the U.S. and Canada. When a decision about their patients included just two options-in this case, prescribing a drug (Motrin) or sending the patient to an orthopedic specialist, the majority chose the drug. But when the researchers added to the choice a drug comparable to Motrin so that three options were then available, the doctors behaved much like the undergraduates struggling with their choice of money, one pen, or two. "Faced with a more conflicted decision between alternative drugs," says Shafir, "most of the doctors sent the patient to orthopedics."

CONFORMITY RULES
Associate professor of Psychology Deborah A. Prentice, a student of conformity and group behavior, has been observing undergraduate conduct since she arrived at Princeton eight years ago. She is especially interested in alcohol consumption on campus and how the perception that "everybody drinks" affects the drinking behavior of students.
According to a recent national survey of drinking on campuses, 42 percent of Princeton students classify themselves as heavy or "binge drinkers," while 46 percent report they are moderate drinkers and 12 percent say they don't drink at all. These figures are close to the national average for four-year colleges. Despite the high percentage of binge drinkers as reported in this and several other surveys, Prentice believes that "privately, many Princeton students have misgivings about drinking to excess."
The problem is that they often don't express their misgivings publicly, and-contrary to their better judgment-they may even engage in the heavy drinking they silently deplore. Prentice attributes such behavior to a kind of peer pressure rampant at Princeton. Psychologists call it "pluralistic ignorance"-the belief that one's attitudes are out of sync with the group's, even when everyone's behavior is the same. A study done by Prentice and Professor Dale T. Miller in 1991 showed that pluralistic ignorance has a negative impact on campus social life. Many of the women respond by dropping out of the social scene at the eating clubs (where most drinking occurs), while some men may become binge drinkers themselves.
Prentice believes that students may engage in such behavior in an attempt to "fit in" better. A study that she and Professor Nancy Cantor conducted of student experience at Princeton, Columbia, and Amherst convinces her of the importance students place on fitting in. For reasons she believes are mainly structural, the pressures to find a niche in campus life were especially strong at Princeton and Amherst, "perhaps because they are small, residential, and have fairly homogenous populations."
Prentice has looked at the drinking behavior of Princeton students of various backgrounds. She has found that as a whole, members of minority groups drink less. She points out that social events at the Third World Center, for example, generally involve less consumption of alcohol: "These students appear to have a culture built around other things." At the other end of the behavioral spectrum are male athletes. Says Prentice, "Being able to drink is apparently one of the social norms of many athletic teams."
None of this makes Princeton particularly stand out from other colleges, and Prentice thinks that its students may actually drink less than statistics suggest. Yet the perception of heavy drinking persists. Says Prentice, "This may have to do with how social life is defined here. On most other campuses, drinking occurs in various social contexts, and it doesn't appear to be the focus." She points out that when Princeton students attend a concert or a prom, drinking is seldom an important part of the scene. But in gatherings of certain fraternities and at the eating-club parties, it is the central activity.
Prentice adds that since she arrived at Princeton in 1988, the situation has improved, and she credits the efforts of the administration and club graduate boards to discourage excess alcohol consumption. The clubs, she says, "have become more responsible and much more strict about controlling underage drinking."

BE PROUD! BE RESPONSIBLE!
One form of self-destructive behavior-the failure to practice safer sex, which significantly raises one's chances of becoming infected by the human immunodeficiency virus (HIV), the cause of AIDS-threatens the lives of countless young people in America's inner cities. Professor John B. Jemmott, a specialist in health psychology, collaborates with other psychologists and health professionals (including his wife, Loretta Sweet Jemmott, a professor of nursing at the University of Pennsylvania) who are working to stem the rapid spread of HIV among urban adolescents.
Inner-city youth represent an important, yet largely neglected, population in the war against AIDS, for almost half of them have had sex by age 13. Says Jemmott, "If you look at the data on AIDS cases in the United States, you find that only about 1 percent of them are adolescents. But about 20 percent are in their 20s. Because HIV can take about a decade to develop into full-blown AIDS, most of these individuals were probably infected in their teens."
Jemmott and his collaborators have been working for nine years to increase AIDS awareness among such adolescents, and their efforts have now begun to achieve national attention. The U.S. Centers for Disease Control has identified as effective a curriculum based on Jemmott's research. "Be Proud! Be Responsible!" is built around workshops, or "interventions," designed by Jemmott to teach adolescents about AIDS and how to avoid contracting it. In a series of studies, Jemmott has focused on black adolescents in the inner cities of Philadelphia and of Trenton, New Brunswick, and Newark, New Jersey. He points out that "28 percent of AIDS patients are African-Americans, even though this group represents only 12 percent of the U.S. population."
In developing the program, Jemmott used practical information collected from focus groups, along with theories of social cognition and planned behavior. The members of the focus groups were inner-city adolescents. They talked about their beliefs about HIV and AIDS, their sexual behaviors, why they engaged in sex, and their feelings about safer sex. (The program encourages students to practice "safe" sex-abstinence-but recognizes that they are more likely to engage in "safer" sex, the knowledgeable and habitual use of condoms.)
A typical intervention includes a group of six to eight adolescents and one adult facilitator. They are together for an average of five hours, so it's important that the activities be fun as well as educational. Videos, rap sessions, and AIDS-knowledge games help keep the kids engaged. In an activity called AIDS basketball, they divide into teams and score points for correct answers to questions about AIDS. "That's our favorite game," says Jemmott. "It's fun and competitive, and everybody enjoys playing it."
Jemmott hopes such efforts will influence attitudes, which in turn will change behavior. Adolescents, he notes, are particularly at risk because most of them believe they are invulnerable. While interventions discuss abstinence as the most effective way to prevent AIDS and other sexually transmitted diseases, they also deal openly with condoms, including lessons on how to use them effectively. Although the lessons are aimed equally at boys and girls, it is the latter who usually must assume the initiative. "It takes confidence for a teenager to insist on using a condom," says Jemmott, "and if she isn't sure she can do it, she won't even try."
Interventions also teach self-confidence. A video that is part of the "Be Proud! Be Responsible!" curriculum features a scene from one of Jemmott's interventions, in which a girl insists to her unwilling companion that they use a condom that evening when they have sex. When her skeptical partner asks her why she would insist on such an "unnatural thing," she replies, "Because I said so. I respect myself more than to let you get me pregnant or catch a disease. . . . I have a life ahead of me."
For a young African-American woman, confidence in herself and the ability to marshal a convincing argument to a partner are critical. Says Jemmott, "Slightly more than 50 percent of women with AIDS are African-American women. And since babies are often infected by the mother, it's roughly the same percentage for pediatric cases."
Jemmott and his collaborators are looking forward to the implementation of "Be Proud! Be Responsible" on a national scale. Their research shows that in the four cities where the pilot program has been in effect, it has achieved a measure of success. In follow-up studies, participants knew more about AIDS, had more positive attitudes toward safer sex, and reported engaging in fewer risky sexual behaviors than did nonparticipants.

HOW LEARNING WORKS
We've all experienced some emotionally upsetting moment-hearing that a friend or loved one has died, for example-and found that years later we can recall minute details surrounding the receipt of that shocking news. So in a sense, it shouldn't surprise us that in her laboratory studies, Assistant Professor Tracey J. Shors has discovered that exposure to stress can improve learning and memory.
Of course, most of us have also experienced situations when we've been stressed to the point of distraction, making it difficult or impossible to take in information. For most neuroscientists, says Shors, "the accepted model of behavior assumes that stress leads to a loss of control and a sense of helplessness" that retards learning.
Most people think that stress is bad for you," she adds, "but we have found that some stress actually enhances the ability to learn." Working with laboratory rats, she has discovered that learning a task improves when preceded by some "aversive event" (a mild shock to the tail, for example) that mimics emotional trauma in humans. Another, less intuitive finding is that the same rat's ability to learn remains enhanced in the absence of further shock so long as other environmental cues remain present. Shors's experiments have also shown that after stress, even the "dumbest" rats (those that had shown an inability to learn even the simplest tasks) can be taught. "These studies suggest there's a dormant capacity to learn that is hidden in every creature, and this potential can be stimulated."
Shors and her colleagues have already isolated the major neurons (nerve cells) and neurotransmitters and receptors (biochemicals that control the electrical signals between neurons) involved. She believes that once scientists discover more about these biomechanisms, the knowledge could be harnessed in ways that will make learning easier.
Recently Shors has been collaborating with Gary S. Lynch *68, a neuroscientist at the University of California, Irvine, who has developed a biochemical compound that enhances electrical transmission in the brain. Shors has been working with him to test whether the compound improves the brain's ability to process information. Its effect, she says, "is like higher fidelity. The cues in the environment become more salient-crisper, clearer, bigger, more intense." Test animals, she adds, react to it in ways that recall the behavior of rats learning under stress. She thinks the compound and stress may have the same biochemical effects on the brain and may stimulate learning in similar ways. A biotechnology company is now testing the compound in the hope that it will lead to a marketable drug for combating Alzheimer's disease and other afflictions affecting memory and learning.
Shors's investigations of enhanced learning will get a boost-literally-in the spring of 1998, when NASA sends her experiments aloft aboard the Space Shuttle. The mission will be devoted to probing the physiological effects of space flight and zero gravity. She and other scientists believe that the rigors of space flight may affect the brain-and learning-in ways similar to what she's seen in the laboratory. As a principal investigator on what NASA officials are calling Neuro-Lab, she will coach the astronauts/researchers at Princeton in experiments they'll perform on themselves aboard the Shuttle.

THE COCKTAIL PARTY PROBLEM
Anyone who's ever uttered the phrase "It's on the tip of my tongue" knows the frustration of trying to recall what Professor Anne Treisman would call a "memory trace" in the brain.
Treisman has spent years sorting out the process by which we attend to one thing and ignore others, and the effect this may have on our ability to remember it later. Early in her career, she was intrigued by what cognitive psychologists refer to as "the cocktail party problem." How, in a roomful of noisy chatter, do two people manage to separate their conversation from the others around them? And how is it that some piece of a background conversation (for example, the mention of a familiar name-perhaps one's own) registers in a listener's consciousness while he or she is oblivious to the rest? The brain seems to select certain auditory signals while rejecting others.
In a series of experiments, Treisman had subjects don headphones and listen to two different messages, one in each ear, then asked them to focus on understanding the message in one ear while ignoring the message in the other. Afterward, she asked them to recall what they had heard in the right ear. "They typically knew that a voice was coming from the right ear, and that it was a man's rather than a woman's, for example, and roughly how loud it was," she says. "But they rarely knew the content of the ignored message." But if the listener's name was mentioned in the right ear, he sometimes picked it up. Occasionally a listener was also conscious of parts of left-ear conversations which related to messages heard by the right ear.
Was the listener subliminally acquiring the entire contents of both conversations while his brain consciously accessed only parts of them? Treisman's experiments suggested not. Her conclusion at the time, she says, was that we all have "limits to perception. We don't fully identify every sound, every object, every word that's around us. We only identify the relevant or important ones because we lower our threshold for detecting them."
She believed that similar processes govern visually acquired memories, although the brain's ordering of images is more complicated. In hearing, she says, "a person mainly focuses on one speaker or one stream of sound. But with vision there's a whole lot coming in-a person can see a whole scene. There are many more questions we can ask about vision."
Treisman turned to visual attention after physiologists discovered that the brain analyzes scenes by sorting them according to some 30 "maps" in the brain, "all specializing on some particular aspect of the scene, like motion or color," she says. She set out to test how the brain puts together these maps so that we see a scene as a coherent whole. In one series of experiments involving a search task, she presented a subject with a crowded display and asked him to look for a specific object. If she defined the object by a single feature such as color or shape and it differed from all the other objects in the display, the object stood out. "The subject didn't need to pay strict attention," she explains. "He could do this with his attention dispersed over the whole display." But when she defined an object by a combination of features-for example, as a red vertical line among red tilted and blue vertical lines-then the subject examined each item singly, and the time it took to find it increased.
"It seems," she says, "that focused attention is needed in order to bind the features of objects together in the right combinations." When displays are shown too quickly to allow attention to individual objects, Treisman found that subjects see many "illusory combinations" such as a gray shirt and blue pants, when in actuality the shirt was blue and the pants gray. Her more recent research has shown that subjects can also "remember" shapes they were unaware of having previously seen: some unconscious part of their brain records the unattended shapes, and the brain retains these unconscious "memory traces" for as long as a month.
The results of her visual experiments now cause her to question her earlier conclusions about auditory perception. She believes that the brain registers and retains more information, whether acquired through sight or sound, than she had thought.
So the next time you're at a cocktail party, be aware that you may be absorbing more information than you think. But you'll have to work at retrieving it.