Scientific American Mind - 09.2019 - 10.2019

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rehearsal’ could encourage stronger
connections between neurons that
code for the memory,” he says.
It is well known that the brain gets
busy when we think we’re giving it a
rest during sleep or meditation. The
new findings may be related to the
memory consolidation we undergo
while snoring away. Schuck explains
that the hippocampal replay during
sleep probably helps form and store
memories. One open question is
whether a role for replay exists
during dreaming as well: the twisting
of recent events into those phantas-
magoric nocturnal narratives may
serve to process and store—or toss
out—our recent experiences.
Schuck and Niv plan to use their
brain-analysis technique to explore
how planning tasks may be related
to replay. They want to investigate
whether effective planning entails
retrieving and replaying past experi-
ences to better optimize the way we
approach the future.
“We think our new methods will be
a door opener to look in much more
detail at replay in humans,” Schuck
says. “We hope that our new meth-
ods pave the way to look at these
things in the future.”
—Bret Stetka


“Missing” Wallets
with More Cash
Are More Likely
to Be Returned
A massive global study with 17,
planted wallets found similar
patterns among most of the
40 countries involved

YOU FIND A LOST WALLET. Do you
return it? Do you think other people
would return it? It is a bit of a hassle.
And what if there’s a little money in
the wallet? A lot of money? Who
couldn’t use a little extra cash?
These are the questions at the heart
of the most extensive experiment in
civic honesty to date, published on
June 20 in Science. And the results
are remarkable and encouraging.
Most of us would predict that the
more money is at stake, the more
likely individuals are to keep the
wallet. Even economists who study
incentives expect people to pocket
the cash. But human beings deserve
more credit than that. Over three
years, a team of economists left
more than 17,000 wallets containing
varying amounts of money at civic

institutions in 40 countries, then
measured how many were reported
to their owner. Rates of return varied
greatly, from 14 percent in China to
76 percent in Switzerland. But
strikingly, in 38 out of 40 countries,
the more money a wallet contained,
the more likely people were to return
it. “People are a bit too pessimistic in
their view of human behavior,” says
economist Michel Maréchal of the
University of Zurich, one of the lead
authors of the study.
Even the researchers believed the
opposite would be true. After explor-

ing possible explanations for their
finding in follow-up studies, they
concluded that people everywhere
were motivated by a combination of
altruism and an aversion to viewing
themselves as a thief.
“This is an amazing study and an
important contribution,” says econo-
mist Marie Claire Villeval of the
French National Center for Scientific
Research, who was not involved in
the work. She found it especially
striking that more money generated
stronger moral dilemmas. “The
psychological cost of not returning GETTY IMAGES

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