Gambling on experience
Perceptions of risk can get pulled in opposite directions
By Bruce Bower
Data, like children, can be raised wrong. Then they become an embarrassment. Consider the retraction on
February 2 of a study suggesting that
the measles-mumps-rubella vaccine
had caused a small number of children
to develop autism. The now-debunked
study, published in 1998 in a major med-
ical journal, fueled parents’ fears about
vaccinating children. So it stands to rea-
son that reluctant parents, upon reading
about the retraction, will drag their kids
to the doctor for a shot and a lollipop.
“There’s an explosion of interest in
studying how people acquire the information on which they base risky decisions,” says psychologist Craig Fox of the
University of California, Los Angeles,
who helped generate an influential
model that predicts how people will
make gambling decisions depending on
descriptions of the odds.
People who learn about the like-
lihood of encountering a low-probabil-
ity, high-impact event via descriptions
that include precise probabilities tend
to overestimate, by a lot, the chances of
that event actually occurring. Vaccine-
o-phobic parents have typically never
seen a child sink into autism after an
MMR injection and never will (SN
Online: 2/3/10). But they have heard
scary secondhand accounts, read celeb-
rity-penned tales of vaccine horrors
and scanned government statistics on
the minuscule but still real chances of
side effects unrelated to autism. These
parents sit on what might be called the
“descriptive cusp” of risky decision mak-
ing. External information prompts them
to overestimate kids’ likelihood of suf-
fering actual MMR side effects. Autism
looms menacingly in this context.
