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If someone told you it was possible to communicate gratitude to
a complete stranger with a two second touch, would you believe it? Although the
power of speech allows us to imbibe great subtlety and complexity in our
messages, psychological researchers have demonstrated that something as complex
as gratitude or sympathy can be communicated with a simple touch.
In social species, prosocial emotions
are those that promote the well-being of the group. By engaging in acts of
trust and cooperation, social groups survive. Parents and offspring form
attachments, and individuals act in mutually beneficial, altruistic ways to sow
trust between one another. A growing number of studies on touch and emotion
reveal our deep-seated need for human contact and warmth. Touch may be the key
for communicating prosocial emotions, and for promoting group cohesion and
survival.
Dr. Dacher Keltner from
the UC Berkeley Department of Psychology and Dr. Matthew
Hertenstein (now at DePauw University) have conducted
extensive research on how touch communicates emotions. In their 2006
paper Touch Communicates Distinct Emotion, Keltner and
Hertenstein investigated the ability of touch to convey various emotions. Given
the importance of cooperation and altruism in social groups, Keltner and his
colleagues hypothesized that it should be possible to communicate prosocial
emotions through touch alone. For their study, 212 volunteers between the ages
of 18-40 were sorted into pairs called dyads.
In each dyad, one person did the touching (the “encoder”) and the other
received the touch (the “decoder”).
Each dyad sat at a table that was bisected by an opaque black
curtain, and had no opportunity see or hear one another. The decoder was
instructed to place a bare forearm through the curtain. On the other side of
the curtain was the encoder, who presented one of twelve emotions to the
decoder by touching the decoder’s exposed arm. In addition, the encoder was
given freedom to choose how best to communicate each of the emotions, including
anger, disgust, fear, happiness, sadness, surprise, sympathy, embarrassment,
love, envy, pride, or gratitude. The decoder then chose which of the twelve
emotions best described what the encoder was attempting to communicate. Keltner
and Herenstein found that anger, fear, and disgust were communicated at levels
above chance (which was set at 25%) along with prosocial emotions such as love,
gratitude, and sympathy.
Interestingly, this experiment revealed that we use consistent
types of touch to communicate particular emotional states. Research assistants,
unaware of the emotions that the encoders were instructed to communicate,
monitored the “tactile displays” of the encoder on a second by second basis.
Research assistants used a survey of coding systems that is routinely used by
researchers investigating touch. The types of tactile displays, including
tapping, stroking, squeezing, poking, pushing, and tickling, among others, were
noted and quantified in terms of frequency, duration, and intensity. Although
106 different encoders participated in the experiment, they tended to use
similar tactile displays to convey emotion. For example, sympathy was
most likely to be communicated with patting or stroking, while anger was most
likely communicated with pushing.
In a 2009 paper that re-examined this data, Keltner and his team
found some interesting patterns of gendered communication. The dyads were
either Male-Female (where the encoder was male and the decoder was female, and
vice-versa), Male-Male, or Female-Female. Only when the dyad consisted of males
was anger communicated at greater-than-chance levels. Only when the dyad
consisted of females was happiness communicated at greater-than-chance levels.
Sympathy was communicated at greater-than-chance levels only when there was at
least one female in the dyad. One of the more humorous
findings of the study was how helpless men and women were
at communicating specific emotions to one another. As Dr. Keltner explained in
a public lecture, “When women tried to communicate anger to the man he had no
idea what she was doing and he got nothing right. And when the man tried to
communicate compassion to the woman she got zero right. She had no idea what he
was doing.”
The Biology of Touch
Dr. Keltner’s studies on touch and emotion exist within the
context of evolutionary theory. Altruism, the selflessness and concern for the
well-being of others, was even perceived by Charles Darwin as an adaptive trait
and is completely in line with the theory of natural selection he so famously
elaborated.
Receptors sensitive to pressure, warmth, and other triggers,
cause our bodies to release a rush of oxytocin. Oxytocin has been studied in monogamous prairie voles, in nursing
mothers, and in human couples where it is thought to be
involved with the promotion of associative behaviors such as compassion, and
which builds trust between individuals. A more contemporary context for
prosocial behaviors is in competitive sports. In a 2010 paper published
in the journal Emotion, Dr. Keltner’s group correctly predicted better outcomes
in the 2008-2009 season for those NBA teams whose athletes touched one another
most frequently and in a positive manner (e.g. chest bumping, high-fives, hugs,
huddles, etc) early in the season. As Darwin astutely noticed, for social
animals, behaviors that allow us to cement bonds with others should persist
because altruism is an adaptive trait. Chemical messengers such as oxytocin
help to reinforce specific adaptive behaviors such as positive touch.
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Not only does touch foster cooperation within groups, it is
necessary for proper physical and psychological development in infant mammals.
From birth, regular, nurturing touch has been shown to have growth promoting
effects in infants. Pups that are separated from their mothers for prolonged
periods have stunted growth compared to rats who are not separated from their
mothers even though they may be fed the same amount. In a 2003 paper, Dr.
Saul Schanberg and colleagues describe how the “mothering behavior” of female
rats (in this case grooming) stimulates the release of prolactin and growth
hormone in her pups, both necessary for proper growth.
Extending these findings to humans, Dr. Tiffany
Field (from the Touch Research Institute) and others
compared the growth rates of premature infants who were maintained
in incubators without touch (standard protocol) to those who were subjected to
light massage several times a day. Shortly after birth, premature babies
are placed in aseptic environments, where they are fed intravenously and often go
for extended periods without touch. Despite being fed exactly the same amount,
the premature babies who were lightly massaged several times a day gained
21-47% more weight than the premature infants who were not touched. Randomized,
controlled studies with other premature infants have shown similar results.
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In addition to having a well-known calming effect on infants, a
nurturing touch is critical for proper cognitive development. Studies have
shown that babies who are held and touched in a positive way more often also
demonstrate lifelong resilience to stress and improved cognition.
Elderly patients in nursing homes, particularly widows, may also be missing the
warm touch of a loved one. One study observed
that “therapeutic touch” (described as a healing process facilitated by hands)
decreased stress-associated cortisol levels, and the frequency of agitated
behaviors (such as pacing and vocalizations) in individuals suffering from
Alzheimer’s Disease.
Given that western American culture tends to be more touch
averse than many other cultures in which a kiss is considered a standard
greeting, and given what we now know about the importance of touch to our
physical and emotional well-being, perhaps we could apply this knowledge to our
lives more often. Maybe the next time you see a good friend, consider giving
them a pat on the back, a friendly handshake, or when in Rome, a kiss on each
cheek.
Join the Berkeley Science Review at their Bay Area Science Festival event, Touch Me! Sunday, October 27th, from 6-10 PM at The David Brower Center in Berkeley. Click here for details and tickets.
About the Author:
Maria Alvarellos is currently a science
curriculum developer at the Lawrence Hall of Science. She is a Bay Area native
with a background in Conservation Biology, Anthropology and Genetics.
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