CHEMICALS IN SWEAT MAY SHOW OUR HAPPINESS
Humans may be able to
communicate positive emotions like happiness through the smell of our sweat,
according to new research published in Psychological Science, a journal of the Association for Psychological Science. The
research indicates that we produce chemical compounds, or chemosignals, when we
experience happiness that are detectable by others who smell our sweat.
While previous
research has shown that negative emotions related to fear and disgust are
communicated via detectable regularities in the chemical composition of sweat,
few studies have examined whether the same communicative function holds for
positive emotions.
"Our study shows
that being exposed to sweat produced under happiness induces a simulacrum of
happiness in receivers, and induces a contagion of the emotional state,"
explains psychological scientist Gün Semin of Utrecht University in the Netherlands,
senior researcher on the study. "This suggests that somebody who is happy
will infuse others in their vicinity with happiness. In a way, happiness sweat
is somewhat like smiling -- it is infectious."
To determine whether
this emotional chemosignaling extends to positive emotions, Semin and
colleagues examined whether sweat taken from people in a happy state would
influence the behavior, perception, and emotional state of people exposed to
the sweat.
The researchers
recruited 12 Caucasian males to provide the sweat samples for the study. The
participants did not smoke or take any medications, and had no diagnosed
psychological disorders. They were prohibited from engaging in alcohol use,
sexual activity, consumption of smelly food, or excessive exercise during the
study.
The sweat donors came
to the lab, rinsed and dried their armpits, and had absorbent pads attached to
each armpit. They donned a prewashed T-shirt and sat down to complete the study
tasks. They watched a video clip intended to induce a particular emotional
state (fear, happiness, neutral) and they also completed a measure of implicit
emotion, in which they were asked to view Chinese symbols and rate how pleasant
or unpleasant each one was. The sweat pads were then removed and stored in
vials.
For the second part of
the study, the researchers recruited 36 Caucasian females, with no
psychological disorder, respiratory disease, or other illness. The researchers
note that only females were included in this part of the study as women
generally have both a better sense of smell and a greater sensitivity to
emotional signals than men do. The study was double-blind, such that neither
the researcher nor the participant knew which sweat sample the participant
would be exposed to at the time of the experiment.
The women were seated
in a chair and placed their chins on a chin rest. The vial containing the sweat
sample was placed in a holder attached to the chin rest and was opened
immediately prior to the target task. The women were exposed to a sweat sample
of each type (fear, happiness, neutral), with a 5-minute break in between
samples.
Initial data analyses
confirmed that the videos did influence the emotional states of the male
participants -- men who watched the fear video showed predominantly negative
emotion afterward and men who watched the happiness video showed predominantly
positive emotion.
But were these
emotions conveyed to the female participants? Some behavioral results suggest
the answer is "yes."
Facial expression data
revealed that women who were exposed to "fear sweat" showed greater
activity in the medial frontalis muscle, a common feature of fear expressions.
And women who were exposed to "happy sweat" showed more facial muscle
activity indicative of a Duchenne smile, a common component of happiness
expressions. There was no observable association, however, between the women's
facial responses and their explicit ratings of how pleasant and intense the
sweat was.
These findings, the
researchers say, suggest a "behavioral synchronization" between the
sender (the sweat donor) and receiver (the sweat smeller).
Additional data
indicated that women exposed to happy sweat showed a more global focus in
perceptual processing tasks, in line with previous research showing that
participants induced to experience positive mood tended to show more global
processing styles.
But the sweat samples
did not seem to impact the women's ratings on the Chinese symbols task,
suggesting that the sweat-based chemosignals did not bias their implicit
emotional states.
These
findings, while preliminary, suggest that we communicate our positive and
negative emotional states via distinct chemosignals, such that the receiver
produces a simulacrum Humans
may be able to communicate positive emotions like happiness through the smell
of our sweat, according to new research published in Psychological Science, a journal of the Association for Psychological Science. The
research indicates that we produce chemical compounds, or chemosignals, when we
experience happiness that are detectable by others who smell our sweat. of the sender's
emotional state. The researchers note that the fact that some measures
indicated emotional contagion, while others did not, may highlight the
difference between measures of emotion that draw on language versus those that
don't.
The findings have
broad relevance -- emotion and sweat are two core features of the human experience,
after all. But the fact that happiness may be communicated chemically could be
of particular interest to the "odor industry," says Semin, due to its
potential commercial applications.
"This is another
step in our general model on the communicative function of human sweat, and we
are continuing to refine it to understand the neurological effects that human
sweat has on recipients of these chemical compounds," Semin concludes.
Study co-authors
include Jasper H.B. de Groot of Utrecht University; Monique A.M. Smeets of
Utrecht University and Unilever Research and Development; and Matt J. Rowson,
Patricia Bulsin, Cor G. Blonk, and Joy E. Wilkinson of Unilever Research and
Development.
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