22 February 2020 | New Scientist | 31Book
Not Born Yesterday: The
science of who we trust
and what we believe
Hugo Mercier
Princeton University Press
IN 1951 at Swarthmore College,
Pennsylvania, social psychologist
Solomon Asch staged a telling
experiment on groups of eight
students. He showed them three
lines of different lengths and asked
them which one matched a fourth
line. The answer was obvious.
But seven of the students were
in fact actors. When they went first
and gave the wrong answer, the
eighth participant – the real one –
was much more likely to do the
same. This became known as the
“conformity experiment” – proof of
the human tendency to be gullible.
Throughout history, people have
often been portrayed as credulous.
Preachers see the trait in those who
believe in gods other than theirs.
Atheists bemoan the credulity of
all believers. Conservatives see it
in those who revolt. Leftists say it
explains why more people don’t.
In Not Born Yesterday, cognitive
psychologist Hugo Mercier argues
that actually we aren’t easily fooled,
wielding psychological, biological
and historical evidence to make the
case that humans are hardwired to
work out who and what to believe.
While the complexity of our
communication makes us more
adaptable, it also means staying
open to beneficial messages and
alert to harmful ones. That is
why, Mercier says, we have “open
vigilance” cognitive mechanisms,
the most basic of which he calls
plausibility checking. This involves
comparing new information with
existing beliefs, draw ing on the past
reliability of sources and checking
new messages against intuitions.
Mercier bolsters his case with
examples from comparative
biology. For example, why do fit
Thomson’s gazelles jump up and
down rather than run when they see
predatory wild dogs? How does this
deter the dogs from chasing?
No one knows for sure – it might
be a form of deception. But Mercierargues that dishonesty (in prey or
predator) would requires gullibility
to endure, and the need for that
gullibility to confer benefits means
that it can’t survive as a stable trait.
History backs Mercier up. In Nazi
Germany, anti-Semitic propaganda
was only effective in areas with high
levels of existing prejudice against
Jewish people. He also cites research
on US political campaigns that
concludes that their impact on
voters is negligible. Studies showthat fake news can spread smears
about politicians, but only among
those who already dislike its targets.
But what about creationism or
anti-vax beliefs? And surely the
open vigilance mechanisms of those
who fall for 9/11 or moon landing
conspiracy theories are failing
them? Conspiracy beliefs are,
perhaps, where Mercier is at his
weakest, as he argues these aren’t
down to gullibility but occur as
a result of plausibility checking
operating on “poor material”.
For Mercier, conspiracy theories
are held as reflective beliefs that
can remain insulated from our other
beliefs and actions. These contrast
with intuitive beliefs, from which
we freely draw inferences and use
to ground our actions. Couldn’t the
same be said of those who accept
climate change science yet still fly
or eat meat? Maybe it isn’t so binary.
Despite this, Mercier’s insights
may help us learn more about why
we can get things wrong. At the risk
of being seen as credulous, I’d say
he makes a strong case for gullibility
being a far less prevalent and
important trait than we thought. ❚Do political campaigns, like
that of Bernie Sanders in
the US, have much effect?
Nic Fleming is a science writer
based in Bristol, UKJIMWEST/AL
AMYWon’t get fooled again
Are we easily taken in? Nic Fleming finds that we’re not so gullible
and actually have an innate ability to pick up on the implausible
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