a contagion that might not be so bad to encounter. A new
analysis of the running habits of about 1.1 million people
reveals that exercise is indeed contagious — though its
communicability depends on who’s spreading it.
findings, published in the journal Nature Communications, also
reveal that certain relationships are better at spreading the
running bug than others — and could have implications for
the study of other social contagions, such as obesity and
recent years, researchers in a wide range of fields — from
economics and politics to medicine and computer science —
have begun to investigate the ways in which many of our
individual decisions affect the decisions of our peers, and
how behavioral changes may spread through a social network.
behavioural contagions exist," the study authors wrote,
"understanding how, when and to what extent they manifest
in different behaviours will enable us to transition from
independent intervention strategies to more effective
interdependent interventions that incorporate individuals’
social contexts into their treatments."
health and other interventions that effectively could harness
the social network to maximize their benefit would be a real
game-changer, researchers say. But it’s been difficult to
draw conclusions from studies based on self-reporting surveys
(where participants may not be fully honest or aware of their
own behaviors) or laboratory experiments (which may not fully
capture the real-life complexities of causal relationships
within social networks).
this paper, Sinan Aral and Christos Nicolaides of the
Massachusetts Institute of Technology used fitness tracker
data to study the running and activity habits of around 1.1
million people in an actual global social network. The runners
had formed about 3.4 million social network ties; the
researchers analyzed the 2.1 million or so ties for which they
could pinpoint geographic location and weather information for
both users. Over five years, these social media users ran a
collective 350 million kilometers — and their runs were all
automatically posted online for their friends to see, reducing
the issues that come with self-reporting.
same day on average, an additional kilometer run by friends
influences an individual to run an additional 0.3 kilometers.
An additional kilometer per minute run by friends pushes a
person to run an additional 0.3 kilometers per minute faster
than usual. If those friends run an extra 10 minutes, that
person is likely to run about three minutes longer than they
would have. If those friends burn an extra 10 calories, that
person will end up burning 3.5 more calories.
effect is strongest on the same day and appears to diminish
with time, the authors wrote.
scientists found that a runner’s peers did influence him or
her to run more — but they also discovered that not all
users influenced their buddies equally. Individuals were more
likely to be prodded to up their game by less-active peers
than by more active ones. Men were influenced by the activity
of both men and women, but women were influenced only by other
women. Inconsistent runners influenced consistent runners far
more than the other way around.
comparisons may provide an explanation for these
results," the study authors wrote. Social comparison
theory, they added, "proposes that we self-evaluate by
comparing ourselves to others."
we make upward comparisons to peers performing better than us,
or downward comparisons to those performing worse? That’s
been a subject of debate, the researchers said.
to those ahead of us may motivate our own self-improvement,
while comparisons to those behind us may create ‘competitive
behaviour to protect one’s superiority,’ " they
explained. "Our findings are consistent with both
arguments, but the effects are much larger for downward
comparisons than for upward comparisons."
people who we think are our closest fitness "peers"
— particularly those who we think are slightly lower on the
totem pole relative to ourselves — are most likely to get us
to push our limits.
are possible explanations in the scientific literature for the
gender divide too, the scientists added.
example, men report receiving and being more influenced by
social support in their decision to adopt exercise behaviours,
while women report being more motivated by self-regulation and
individual planning," the study authors wrote.
"Moreover, men may be more competitive and specifically
more competitive with each other. Experimental evidence
suggests that women perform less well in mixed gender
competition than men, even though they perform equally well in
non-competitive or single sex competitive settings."
findings reveal how effective monitoring these real-time
networks may be to help scientists design all kinds of
interventions to minimize the spread of social ills and
maximize the spread of social benefits.
granularity and precision with which fitness tracking devices
record real-world health behaviours portends a sea change in
our understanding of human behaviour and social influence at
scale," the study authors wrote. "Compared with
prior studies, which relied on imprecise and frequently
inaccurate self-reports, the potential for these kinds of data
to extend our understanding of social behaviour in real-world
settings is difficult to overstate."
STORY CAN END HERE)
highlights the fact that looking at "average" social
influence may not be the most helpful indicator, especially
when — as this study showed — influence on any given
branch of a social network is not necessarily a two-way
subsegments of the population react differently to social
influence," the authors said. "Such differences
suggest that policies tailored for different types of people
in different subpopulations will be more effective than
policies constructed with only average treatment effects in