Lab
experiment with 'scent samples' suggests humans pick up on others' positive
emotions via sweat
By
Alan Mozes
HealthDay
Reporter
TUESDAY,
May 26, 2015 (HealthDay News) -- As emotions go, happiness usually hides in
plain sight: seen in a broad smile, heard in a raucous laugh, felt in a big
hug.
But
new research suggests there may be a less obvious way to pick up on another
person's positive vibes: smell.
According
to a team of European researchers, happiness may generate chemicals that get
secreted in sweat, and that sweat signal gets sniffed by those around us.
The
experiments also suggest that we not only breathe in the upbeat emotions of
others, but by doing so we actually become happier ourselves.
"Human
sweat produced when a person is happy induces a state similar to happiness in
somebody who inhales this odor," said study co-author Gun Semin, a
research professor in the department of psychology at Koc University in
Istanbul, Turkey, and the Instituto Superior de Psicologia Aplicada in Lisbon,
Portugal.
The
findings were published recently in Psychological Science.
The
researchers noted that prior research has already demonstrated that negative
emotions, such as fear or disgust, can be communicated via odors in sweat.
To
see whether the same holds true for the happier feelings, Semin's team gathered
sweat samples from 12 young men after each watched videos designed to induce a
variety of emotions, including happiness and fear. All the men were healthy,
drug-free nonsmokers, and none drank, consumed smelly foods or engaged in
sexual activity during the study period.
In
turn, 36 equally healthy young women were engaged to smell the samples while
their reactions were monitored. The smell group, explained investigators, was
confined to women because women typically have a better sense of smell than men
and are also more sensitive to emotional signaling.
After
analyzing the facial expressions of the smell group, the research team
concluded that there does, in fact, appear to be a so-called "behavioral
synchronization" between a sweating person's emotional state, the sweat
generated, and the reaction of the person who sniffs that sweat.
Specifically,
that meant that the faces of women who smelled "happy sweat"
displayed facial muscle activity deemed to be representative of happiness.
Sweat
didn't always produce a contagious response in the smeller, however. For
example, those smellers who verbalized having a "pleasant" or
"intense" reaction to a sweat sample did not manifest those reactions
in their facial expressions.
What
is it exactly that makes "happy sweat" infectious?
Semin,
who is also professor of social and behavioral sciences at Utrecht University
in the Netherlands, acknowledged that "we have not demonstrated what the
nature of the chemical compound is in sweat."
Pamela
Dalton is an olfactory (smell sense) scientist with the Monell Chemical Senses
Center in Philadelphia. She said she found the findings "a little
surprising."
However,
"what is interesting about this study is that it suggests a positive
emotion can be communicated -- which in my opinion is far less important in
human evolution and behavior than to be able to transmit and recognize a
negative emotion, such as fear or anger," Dalton said.
For
that reason, Dalton said she "would expect the ability to communicate a
happy emotion to [actually] be less potent than the ability to transmit a
negative emotion."
But
Andreas Keller, a research associate with The Rockefeller University in New
York City, said the study findings make intuitive sense.
"Hearing
happy people and seeing happy people makes you happier," he said, "so
the fact that smelling them would make you happier, too, is probably not so
surprising."
According
to Keller, the next step "would be to find out what the chemical difference
in fear sweat and happy sweat is that mediates these effects. This would open
the door to study what is going on at a mechanistic level."
More
information
There's
more on the human sense of smell at the Social Issues Research Center.
SOURCES:
Gun R. Semin, research professor, department of psychology, Koc University,
Istanbul, Turkey; and Instituto Superior de Psicologia Aplicada, Lisbon,
Portugal, and professor, social and behavioral sciences, Utrecht University,
the Netherlands; Pamela Dalton, Ph.D., M.P.H., olfactory scientist, Monell
Chemical Senses Center, Philadelphia, Pa.; Andreas Keller, Ph.D., research
associate, The Rockefeller University, New York City; April 13, 2015 (online),
Psychological Science
