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| Pychologist
Paul Rozin, AB'56, studies what humans eat--and what divides
yum from yuck. |
| By
Peter Nichols / Photography by Dan Dry |
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At one of their weekly lunchtime seminars, faculty of the University
of Pennsylvania’s Solomon Asch Center for the Study of Ethnopolitical
Conflict gathered this fall to hear Paul Rozin’s talk on “Negativity
Dominance.” Rozin, a psychology professor at Penn and one of
the center’s founders and co-directors, had arranged for the
delivery of some of his favorite dishes from an Italian deli near
his home in suburban Philadelphia. A paper plate heaped with breads,
meats, pastries, and pickled stuffed peppers sat on the table before
him.
“Negative events have this powerful, almost uncancelable quality,”
he began. In the wild, bad experiences usually result in death and
are therefore potent teachers for animals. Negative risks outweigh
possible positive outcomes: There is nothing as positive as death
is negative. Humans too, Rozin told the dozen or so scholars gathered
around the table, are programmed to respond promptly and strongly
to negative experiences. A cockroach in a glass of orange juice,
for instance, elicits a nearly insurmountable sense of disgust,
and people cannot be persuaded to drink it even if they have been
assured the bug was sterilized. There is nothing positive that can
be placed on a pile of cockroaches to make them edible. “Similarly,”
he reasoned, finding an analogy between such disgust and long-standing
ethnic hatreds, “if someone murdered your great-great-great-grandfather
hundreds of years ago, it seems there’s nothing you can do
to get away from that. There’s no counter-cockroach!”
As the conversation continued, Rozin, AB’56, took hearty
mouthfuls of Italian delicacies, returning to fill his plate several
times at the small buffet. It was hard to tell whether his unself-conscious
pleasure derived more from the luncheon fare that he had supplied
or the food for thought, which he also provided.
The author of nearly 200 scholarly articles, Rozin is an authority
on the psychology of food choice. Twice elected a fellow of Stanford’s
Center of Advanced Study in the Behavioral Sciences, he has also
been editor of Appetite and served on the editorial board
of the Journal of Gastronomy, as well as the advisory board
of the Children’s Television Workshop, which produces Sesame
Street. He is currently psychology adviser for the publisher W.
W. Norton, and his expert advice has been tapped by major food producers
like Unilever, Nestle’s, General Foods, McCormick Spices, and
Cadbury-Schweppes.
Although a joint Ph.D. in psychology and biology from Harvard
prepared him mainly for biological psychology and animal research,
Rozin is an intellectual omnivore. In his 36 years at Penn, he has
investigated how humans come to develop food preferences and aversions,
studying the interplay of culture and cuisine, morality and disgust.
To understand what makes people like or dislike certain foods, Rozin
has sunk his teeth into fields as diverse as anthropology, economics,
geography, history, marketing, medicine, psychology, sociology,
and public policy.
He attributes his wide-ranging interests to his experience in
the College, where he matriculated at the age of 16 after two years
of high school. “We dug into a lot of different disciplines
in some detail,” he remarks. “I’m not saying my broad
research style is good or bad, but it’s the way I work. I just
get interested in a problem, and I go where it seems right to go.”
Despite the sensual and intellectual pleasure he derives from
food, Rozin is trim. He possesses what he calls a “rather small”
collection of about 200 cookbooks on world cuisines, particularly
Asian, and sometimes leafs through them for inspiration in cooking
an occasional meal. “But I’m too busy to cook now,”
he confides. “I hardly have time to eat.” He dines out
frequently, particularly as he travels around the world for conferences
and consulting. A self-described neophile, he enjoys sampling unusual
foods and flavors, including Japanese candied locusts and a dish
made of ground, dried, cactus worms. “I love to eat all kinds
of exotic foods and cuisines,” he says, “and have eaten
well nigh everything cooked—almost.” One often-reviled
food that he hasn’t eaten is haggis, a Scottish dish consisting
of a sheep’s heart, liver, and lungs, minced with suet and
oatmeal, and boiled in a pouch made from a sheep’s stomach.
The reason, he claims, is not disgust but lack of opportunity.
For humans, whether doing a power lunch, enjoying a romantic candlelight
dinner, or eating the apple from the Tree of Knowledge of Good and
Evil, food and its consumption are freighted with significance beyond
nutrition. To extract the mix of biological, psychological, and
cultural ingredients that go into people’s daily decisions
about what foods they eat, Rozin has studied a range of foods in
a range of ways. He’s looked at the generational link in how
some cultures acquire and pass on to their children a preference
for initially unpleasant eating experiences, such as the burn of
chili peppers. (In a “hedonic reversal,” he explains,
the fierce burn becomes a sought-after culinary experience.) He’s
found that the sensory experience of chocolate—its rich aroma,
its silky and slippery sweetness—is what underlies people’s
chocolate cravings, not the mildly addictive qualities of some of
its ingredients. Chocolate, he exults, “is a wonderful thing
in the mouth.”
With David Kritchevsky, SB’39, SM’42, a professor at
Penn’s Wistar Institute and an expert in the biochemistry of
nutrition and fat metabolism, Rozin is writing a book to help readers
think sensibly about food and nutrition—and to enjoy eating.
The book is an outgrowth of a course that the two men taught at
Penn. In Diet and Health, students explored the complex mix of scientific
method, politics, and personal issues that help form scientific
consensus over what constitutes the “healthy” diet. For
many Americans, Rozin believes, the concept of a diet filled with
healthy foods has had a pernicious effect.
“One way Americans have spoiled eating,” he says indignantly,
“is by thinking of their blood cholesterol while they’re
doing it—which is nuts! Every bite, for some people, is fraught
with conflict. It may be that we’re obsessed by death. There’s
this sense that we’ll live forever, if we only do it right—and
diet, along with exercise, is currently thought to be the way to
do it right.”
Experimental results about the health effects of eating particular
foods get reported almost immediately, but Rozin argues that, in
many cases, the public has not learned to evaluate such information
in a way that balances risks and benefits. Instead, he says, many
people have adopted simplistic decision-making criteria to help
form judgments about whether particular foods are either good or
bad. Under this heuristic, for example, essential nutrients like
salt and fat may come to be viewed as poisons. Yet, he points out,
“driving is far more dangerous than high cholesterol. If people
cut driving in half and walked more, it would probably do much more
for their health than monitoring their diet on a moment-to-moment
basis.”
According to Rozin, the U.S. medical establishment’s preoccupation
with what foods constitute a healthy diet also has added to American
women’s “normative discontent” about weight and body
image. He cites his recent survey of college students from six campuses
across the U.S. In that study, more than 10 percent of the female
respondents admitted that they are “embarrassed” to be
seen buying a chocolate bar, while 30 percent said they would be
willing to take a nutrition pill—and forgo eating. “About
one quarter of Americans, mostly women,” Rozin adds, “if
asked for the first few words that come to mind when they think
of chocolate, mention both a positive and a negative word: ‘delicious’
and ‘fat.’ They’ve taken this incredibly delicious
food, and they’ve made it into something like a toxin.”
This uniquely American food-poison attitude has inspired the food
industry to develop all kinds of popular products modified to be
“healthier.” The highly processed, fat-free, low-salt,
no-additives cuisine reduces the pleasure of eating and increases
the cost of food, Rozin says. “I’m particularly interested
in this pleasure issue—in being able to enjoy the wonderful
things in life.”
With a French colleague, Claude Fischler, he spent last summer
in Dijon at the Centre European des Sciences du Gout, gathering
data for a comparison of how food functions in American and French
life. He hopes it will become a major study: “I think we have
something to learn from the French.”
If you ask French and American subjects whether fried eggs make
them think of breakfast or cholesterol, Rozin says, the French are
more likely to respond in terms of the former and Americans in terms
of the latter. In one case, it’s in a culinary context; in
the other, it’s a supposedly harmful nutrient. “We tend
to think about what’s in the food that’s either good or
bad for us,” explains Rozin, “and the French think about
it as an experience: It’s eating. They’re thinking about
it in the mouth, and we’re thinking about it in the bloodstream.”
Ironically, recent studies show that life expectancy is about
the same in France and the U.S. The French eat a higher-fat diet,
have higher levels of blood cholesterol, and do not worry about
a healthy diet, yet still have a rate of cardiovascular disease
that is about one-third less than Americans. “The trade-off
between the pleasure of eating and long-term health,” Rozin
says, “is not nearly as stark as Americans make it out to be.”
Attempts have been made to explain this so-called French Paradox
in terms of what the French eat, the most popular account being
the protective effect of consuming red wine. Other explanations
are seldom considered: The French consume fewer calories, snack
less, and eat a more varied diet at a slower pace. Their lifestyle
is less stressful, especially with respect to food, and they probably
exercise more, depending less on cars and more on walking and bicycling.
“It’s not a paradox at all,” Rozin declares. “It’s
only a paradox if you believe that saturated fat is basically the
determinant of heart disease—as opposed to a causal contributor.”
From studying how humans come to divide foods into “the yum
and the yuck,” Rozin has moved over the years to a focus on
the “yuck,” the peculiar nature of human disgust. “Once
I became interested in food and why people like it,” he explains,
“it didn’t take long to realize that the strongest response
people have to food is disgust.” Siding with Darwin, he traces
disgust back to “a basic biological motivational system,”
a response the father of evolution associated with the sense of
taste.
Observed in a number of animals, in humans the characteristic yuck
response is a gape that consists of opening the mouth and putting
out the tongue. Often including nose wrinkling and raising the upper
lip, this facial contortion allows the offending food to drop out
of the mouth and is usually associated with a sense of revulsion,
even nausea. The reflex, which serves as a potent survival instinct
against toxic substances, is particularly vital to omnivores like
humans, who experiment with all kinds of potential foods.
Rozin distinguishes this instinctual reflex from what he calls
“core disgust”—a uniquely human response to the meaning
of a revolting substance rather than to its taste. “Humans
see themselves as quite distinct from (and superior to) other animals,”
he writes in a chapter on disgust in the Lewis and Haviland’s
Handbook of Emotions (1993), “and wish to avoid any ambiguity
about their status by accentuating the human-animal boundary.”
Although humans have developed language and culture and conceive
of themselves as moral beings, they still eat, excrete, and copulate
like other animals—and are profoundly ambivalent about this
aspect of their nature and what it portends. “Disgust,”
he notes, “functions like a defense mechanism to keep human
animal-ness out of awareness.”
At the heart of Rozin’s theory of disgust is the contagion
principle, which represents a kind of thinking that anthropologists
call “sympathetic magic.” The law of contagion states
that when two entities—such as eater and eaten—make physical
contact, a permanent transfer of properties takes place from one
to the other. In a 1990 experiment, Rozin tested people’s implicit
belief in the adage “you are what you eat” by giving several
hundred American college students one of two versions of a short
vignette describing the “Chandorans,” an imaginary tribal
society that hunts marine turtles and wild boars. Half the group
read that the Chandorans ate wild boar and hunted turtles for their
shells; the others read that the tribe ate turtles and hunted boars
for their tusks.
The students were then asked to rate members of the culture for
personality traits and physical attributes that could be associated
with boarness (aggressive and likely to have beards, for instance)
and turtleness (good swimmers). Those who read that the Chandorans
ate boar rated them high on the aggressive scale, while those who
thought of the Chandorans as turtle-eaters rated them good swimmers.
“We know ‘you are what you eat’ is false,” explains
Rozin, but despite sophisticated rational and conceptual faculties
that tell us otherwise, “it nonetheless creeps into our judgment.”
The contagion principle, he says, comes into play with many living
things, like a cockroach or a worm, that people find disgusting
but that don’t really taste bad. Even the meats humans do eat,
such as cows, pigs, and sheep, are rendered more palatable by disassociating
them from their animal origin: rather than eat dead animals, we
dine on “beef,” “pork,” and “mutton.”
In a 1993 survey, Rozin and his colleagues (he most often works
with a colleague at Bryn Mawr College and three of his former doctoral
students at Penn) distributed a questionnaire to gauge respondents’
sensitivity to a list of disgust elicitors that included food and
eating, feces, rotting flesh, gore, deformity, deficient hygiene
practices, inappropriate sex, and death. On the resulting Disgust
Scale, death—whether an actual corpse or the odor of decay—is
a primary elicitor. At the root of awareness, Rozin argues, humans
believe they will be infected by contact with things that remind
them of their animal nature, with death the most threatening attribute
of animal nature.
Rozin and his colleagues theorize that the emotion of disgust
appropriates the behaviors and sensations of the distaste reflex
through “preadaptation,” a process in which an organism
employs a physiological mechanism that evolved for a particular
function to serve an entirely different purpose. Just as language
articulation uses the mouth, tongue, teeth, and lips—all of
which originally evolved for eating—human consciousness, argues
Rozin, accesses the pre-existing distaste system. So obvious and
painful—in short, so repulsive—is the prospect of mortality
that human consciousness must enlist its animal reflexes to push
it away. “Disgust evolves culturally,” writes Rozin, “and
develops from a system to protect the body from harm to a system
to protect the soul from harm.”
As the emotion of disgust is elaborated culturally, it evolves
into a more general feeling of revulsion, a moral emotion associated
with anger and contempt. In a kind of cultural preadaptation, Rozin
theorizes, the biology of disgust is accessed in the formation of
social mores. He calls the process “moralization,” in
which a culture’s moral system recruits disgust and projects
the emotion onto what is considered immoral.
For example, eating high-fat and “junk” food has come
to be seen as immoral in certain sectors of American society. In
a 1995 experiment, researchers at Arizona State University offered
college students contrasting vignettes of students who dined on
fast foods and others who ate a healthy diet. When asked to rate
the two types of eaters, the “you are what you eat” principle
again came into play, with respondents rating the junk-food eaters
less morally worthy and less considerate than the students described
as eating fruits and vegetables.
Researchers have found that vegetarians who abstain from meat
based on moral principles (because it implies killing animals or
wasting resources) are more likely to experience a linkage between
values and food preferences. Rozin—who describes himself as
a “moral vegetarian sympathizer”—has found that such
vegetarians often come to dislike or be disgusted by meat, confirming
a general rule of moralization: disgusting things are more likely
to be thought immoral, and immoral things are more likely to be
thought disgusting. When this stage is attained, the moral principle
has become internalized or “woven into the self.”
As moralization of some entity or behavior takes hold in a society,
a widening consensus builds and the forces of government and major
institutions become aligned against what has come to be seen as
repulsive. Take smoking: Today in the U.S., cigarette advertising
has been severely restricted, tobacco companies and their executives
have been vilified in the media, and legislation has curtailed smoking
in public spaces.
With the implication of disgust in morality, the emotion loses
both its original connections to bad-tasting food and its intermediate
function of avoiding reminders of animal nature and death. At this
level, says Rozin, disgust expands to a general system for putting
out of mind—like the clusters of ostracized smokers huddling
on sidewalks outside office buildings—anything one’s culture
considers offensive.
“Disgust becomes, in many ways, the emotion of civilization,
in the sense that much of the civilizing process involves developing
distinctions between animals and humans, and a special sensitivity,”
says Rozin, traveling far beyond the study of food likes and dislikes
to the essence of humanity. “It’s hard to imagine civilization
and culture without disgust, the sense of what’s inappropriate.
If you could imagine a person who is free of disgust, it’s
hard to imagine how they would be distinctly human.”
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