MADISON, Wis. -- There is more to beauty than meets
the stranger's eye, according to results from three
studies examining the influence of non-physical traits
on people's perception of physical attractiveness. The
results, which show that people perceive physical appeal
differently when they look at those they know versus
strangers, are published in the recently released March
issue of Evolution and Human Behavior.
In many studies evaluating physical attractiveness,
people are often shown an array of strangers' photos,
computer-generated images or line drawings and asked to
identify which ones, based on differences in physical
features, are most attractive. Results from these
studies suggest that physically attractive traits
include high degrees of bilateral facial symmetries,
such as eyes that are identical in shape and size, and
waist-to-hip ratios of 0.7 for women and 0.9 for men.
"You can find study after study that focuses on
which waist-to-hip ratios or particular facial features
people find physically attractive, and these studies
have captured popular attention," says Kevin
Kniffin, an honorary fellow in the anthropology
department at the University of Wisconsin-Madison and an
adjunct assistant professor at Binghamton University.
Kniffin co-authored the Evolution and Human Behavior
paper with David Sloan Wilson, an evolutionary biologist
at Binghamton University.
While these past studies do show which features people
find physically appealing after just a glance, they
overlook the non-physical traits that may influence a
person's perception of another's beauty over time. In
other words, people may see physical attractiveness
differently when they know that person's other
qualities, usually invisible to strangers, says Kniffin.
Pressures selecting for the influence of non-physical
traits on the perception of physical beauty have
operated across millennia. According to evolutionary
theory, many animals, including humans, are attracted to
those who are likely to increase their own fitness --
the likelihood of surviving and reproducing.
In the case of humans, "the fitness value of
potential social partners depends at least as much on
non-physical traits -- whether they are cooperative,
dependable, brave, hardworking, intelligent and so on --
as physical factors, such as smooth skin and symmetrical
features," says Wilson. "It follows that
non-physical factors should be included in the
subconscious assessment of beauty."
To systematically consider the influence of
non-physical traits on how people who are familiar with
each other perceive physical appeal, Kniffin and Wilson
conducted three studies of beauty involving people who
know each other and people who don't. For all studies,
the participants were asked to rate physical
attractiveness and non-physical traits such as liking,
respect and talent. Strangers rated only physical
In the first study, the participants rated people
photographed in high school yearbooks, including one
that belonged to each participant. In the second,
members of a college sports team, as well as strangers,
rated each team member. Finally, students in a summer
archaeological excavation course rated each other on the
first day of class and six weeks later at the end of the
course. "In each case, non-physical traits known
only to familiars, such as how much the person was
liked, respected and contributed to shared goals, had a
large effect on the perception of physical
attractiveness that was invisible to the
strangers," says Wilson.
Each study provided an illustrative example of this
finding. For instance, one middle-aged subject who had
not seen the familiar person photographed in the
yearbook for decades responded with absolute disgust
when she recalled the person's character and described
that person as ugly. In the sports team study, team
members considered the slacker to be ugly and one of the
leaders to be physically attractive, while strangers,
blind to the members' relative contributions, rated them
as equally attractive on the basis of photographs. And,
after six weeks of working together on an archaeological
dig, students' perception of physical attractiveness
changed based on interactions during the course.
In a world where people are bombarded with messages
about physical attractiveness from magazines, television
and advertisements, the researchers say their results
point to the influence of other traits on people's
perception of physical beauty. Kniffin adds that he
hopes these findings may encourage the consumers of this
information to rethink the value of cosmetic surgery,
especially if it involves risk.
At the end of their paper, the researchers offer this
beauty tip: "If you want to enhance your
physical attractiveness, become a valuable social
Look at what that did for Abraham Lincoln.
"During his lifetime, he was regarded as so ugly
that he once quipped, 'If I were two-faced, do you think
I would be wearing this one?'" says Wilson.
"Yet his physical features have become beloved, not
because of their physical qualities per se, but because
of what they stand for."