Author's Note: I request you remember the ground rules for this post: I am taking it as a given that vaccines are effective and safe. If you would like to dispute this fact, then please review this obnoxiously hyperlinked sentence.
In this series, I am attempting to answer the question, “What
keeps people from vaccinating their children?”
We are discussing vaccination behavior as a balance between the
perceived risks and benefits of the choice.
In the first post of the series we discussed how we perceive benefits. In the previous post we discussed the
cognitive mechanisms of risk assessment as related to the affect
heuristic. Here we shall continue the
discussion of risk and finish by exploring its relationship to our
humanity.
Loss Aversion
People
dislike losses more than they like gains4. Psychologists call this loss aversion. Many studies
have demonstrated this tendency. When
participants were asked how much they would have to win to participate in a
coin toss where they would lose $50 if they called it wrongly, people set the
average price around $1003. That is, a participant had to win twice as
much as she could lose to make it “worth her while.” Loss
of what you already own is much more painful than a gain is pleasurable.
Loss aversion affects more than
financial gambles. When a dad weighs the
risks of vaccines, a prominent fact in his mind is that his child is healthy now.
Suppose he consents to give his son the MMR vaccine at 1 year of age,
and then at 3 years he’s diagnosed with autism.
If dad convinces himself of a causal relationship between the two
events, then the sense of loss he would feel from his complicity seems
unbearable. If he compares that
potential loss of his child’s good health against the potential benefits of
preventing vaccine-preventable diseases (VPDs), uncertain and far in the future
as they are, then loss aversion can be the key factor in his decision.
Regret
Related to loss aversion, people
prefer sins of omission (bad outcomes from inaction) compared to sins of
commission (bad outcomes from action)4. Consider two investors. The first owns stock in company A but
considers selling it to buying company B.
He decides not to buy, and later learns he would have gained $2,000 if
he had purchased B. The second owns
stock in B and then sells it for stock in A.
He also learns he would have $2,000 had he not sold B. Which investor regrets his decision more? When asked this questions, 92% of respondents
say the second3. Regret is a powerful emotional manifestation
of loss, and our minds feel more regret when our actions are the cause of a bad
outcome.
Now
consider again the dad who is already uncertain about vaccines and is weighing
the risks. He is the one who has to
consent to the shot. His action of
consenting directly results in the vaccination of his child. If his child develops autism and he believes
vaccines were the cause, then he will profoundly regret giving his consent, as
he believes he is part of the
cause. However, suppose he decides not
to vaccinate. This is the inactive
option since his child is naturally unvaccinated. If his child catches severe pneumococcal
pneumonia, it is easy to imagine that he will
more readily forgive himself for his inaction and experience less regret. In the calculus of choice, regret is an
important variable.
Reference Frames
Both loss aversion and regret
depend on your frame of reference. What
is the default position against which losses and gains are compared? If asked
who is happier, someone with $2000 who wins $500 or someone with $3000 who
loses $500, the obvious answer is the first person, by a lot3. If satisfaction only depended on money, then
they should be equally satisfied as they have the same amount at the end of the
transaction. However, we see that the
starting point matters; it determines whether a final state is a loss or a
gain. If a third person initially had
$2000, was given $1000 briefly and then had $500 taken away, we intuitively see
this person is less unhappy (and probably quite happy) compared to the second
person above. This third person,
although briefly owning $3000, feels little ownership of it – her frame of
reference is starting with $2000 and thus her final state is a net gain of $500.
Applying this logic to vaccines, we can see
that the above examples of loss aversion and regret depend on the reference
frame of the unvaccinated child with his current state of health. From here, perceived injury by a vaccine is
viewed as a loss of health and prevention of a VPD is a gain. Now imagine a society with a robust public
health program that has swayed public opinion heavily in favor of vaccines. Society as a whole views the state of being
vaccinated as the default state, where a child’s health should be. Now when a
parent considers not vaccinating, that is an act of commission, as it is their
choice (choosing not to) which caused the deviation from the reference state4. Similarly, he will feel less regret if he
believes his child suffers an injury from the vaccine. He was merely doing his fatherly duty of
maintaining the reference health state.
Unfortunately for many people, the vaccinated child is not their
reference state and loss aversion and regret come to bear negatively on their
decisions.
Overestimating Small
Probabilities
In general,
humans are terrible with statistics, especially with small probabilities. Research consistently demonstrates that we
overestimate the frequency of rare events.
One group of researchers showed that people consistently overestimate
the percentage of death from rare causes7. This is particularly true
when the events are vivid, as other researchers have shown that people judge
death by tornado to be much more frequent than death due to boring, everyday asthma,
even though asthma kills 20 times as many people3. Consider the fear the 9/11 terrorist attacks
caused compared to the fear people felt on that same day towards a common, yet
much more dangerous, activity such as driving.
Granted, many factors contribute to the fear caused by terrorism, but
among them is the fear that you will be the victim of an attack. This fear is irrational compared to the risk
we face everyday by getting into a car.
Similar to
overestimation, we overweight the importance of small probabilities. How much would you pay to increase your
chance of wining $1000 from 0% to 5%?
What about to increase your chances from 5% to 10%? The latter bet is
double the chance to win compared to the former, so would you pay twice as
much? Studies demonstrate that you most likely would not; you would pay
proportionally more to go from 0 to 5% than from 5 to 10%3. There is substantial psychological benefit
when a person moves from no possibility of winning to any possibility of winning, what researchers call the possibility effect. There is proportionally less benefit when a
person moves from a small chance of winning to a slightly less small chance,
and people reflect this preference in the price they are willing to pay for
such a gamble.
Now adverse
reactions (AR) to vaccines do happen. All of them are rare; the bad ones, such
as severe allergic reactions, are exquisitely rare8. Note that the possibility unfortunately
does exist. Given the above discussion,
we know that the undecided parent will see the AR rates as much more frequent
than they truly are, particularly because they are so vivid. For the same reason, he will also overweigh
the specter of ARs in his risk calculation.
Availability Cascade
We can use
these observations about risk assessment to explore a powerful, culture-changing
process that strongly influences our response to vaccines, the availability cascade (AC). Availability
refers to the degree of familiarity we feel towards a topic. We feel familiar towards things we’ve been
more exposed to. If a topic is more
available in our minds, then we will tend to overestimate its frequency, feel
like we know more about it than we actually do, and be more likely to use what
we know to draw further conclusions3.
An AC, as Kahneman defines it, is
“a self-sustaining chain of events, which may start from media reports of a
relatively minor event [author’s addition: or Twitter messages or Facebook
statuses] and lead up to public panic and large-scale government action3”. This is not a belly-flopping Corgi video that
you laugh about at work the next day; this is a piece of news that changes your
daily life. This is a viral idea that
becomes a plague. Broadly speaking, this happens when a story catches the
attention of a subset of people who become concerned. The media reports the concern as a news story
itself, which reinforces the concern in more people. The cycle repeats until
the issue gains so much momentum, it has to be addressed on a large scale. I find it interesting that it’s called a
cascade, which may evoke the gentle image of a waterfall in many people’s
minds. However, I don’t think image does
the idea justice. I see the process as more powerful and chaotic, more akin to
the violent cascade of radiation in nuclear fission.
Let’s use
MMR causing autism as an example. In
1998, a researcher makes up a bunch of stuff, writes a paper, submits it to a
respected medical journal and it gets published (and later retracted). This is, unfortunately, not too unusual an event. The news media prints an
article about the paper. A portion of the
population that was already suspicious of vaccines hears about the article and
starts to make a ruckus. A pretty person
with a loud voice lends her celebrity to their concerns. The controversy between nerdy scientists with
their pocket protectors and taped glasses who say vaccines are safe and the
supermodel who just knows for certain that vaccines caused her child’s autism
is too juicy for the news media to ignore.
So the coverage intensifies, adding undue legitimacy to the
controversy. The anti-vaccination
arguments begin to bloom and spread like a mushroom cloud –“toxins!, mercury!,
overwhelmed immune systems!, government cover-ups!” With the force of a bomb, they impact parents
at their deepest fear, the safety of their child. There the radioactive ideas remain, sizzling with
intense doubt. This doubt ignites our
risk assessment strategies. The affect
heuristic, loss aversion, fear of regret, overestimating and overweighting
small probabilities all burn brightly in the concerned parent’s mind. The process is repeated millions of times, in
the minds of anyone who hears such arguments.
Governments, doctors and scientists respond with a slew of non-made-up
studies which state that the MMR vaccine does not cause autism. Unfortunately, the facts do not fix the fears because they do not survive the
cognitive processes of risk assessment.
So the cascade continues, its explosions echoing through history, its
shockwaves reverberating into the future.
The Facts do not fix
the Fears
If there is
main point for healthcare providers it is this: facts are not
communication. Too often, doctors sit
with patients and tell them the facts of their illness and how to treat
it. The patient returns 1 month later
having done nothing the doctor suggested and we blame it on
non-compliance. Each fact a patient hears
has to navigate the gauntlet of our cognitive machinery. If we do not communicate with an appreciation
for people’s loss aversion, heuristics and biases, or terribleness with
probabilities, then we are not communicating with a human brain, we are
speaking to ourselves. The only way to do this is both unfortunately
cliché and extremely powerful: listen. By listening, we can identity the patient’s cognitive
process and speak not only to their intellectual gaps, but also to their doubts
and fears.
If there is
a main point for anybody with an opinion about vaccines it is this: we all use
these same cognitive mechanisms, therefore we are all at risk of the same thinking
errors. By extension, we are all wrong
about a lot of things a lot of the time. There are members of our species that came up with scientology, believe that Reptilian overlords run the government, and think the Twilight movies are actual artistic achievements, and now this
species is debating the merits of vaccines.
It should surprise no one that there are people who conclude wrong things, nor should it surprise you when you are one of those people. If we understand this, we can approach
debates with humility, understanding we are not so different than our opponents.
After all, it’s certain that one of your beliefs appears to someone as
anti-vaccination beliefs appear to you.
Now don’t get me wrong, this is a serious issue, and we are ultimately
debating over the health and safety of our kids. But in order to convince someone why they are wrong we have to first understand why they are wrong. We have to understand the quirky shenanigans
of cognition and humbly acknowledge that no matter which side of the debate, we
all have similar brains that are quite fallible and, therefore, quite
human.
References
1. Smith PJ, Humiston SG, Marcuse EK, et
al. Parental Delay or Refusal of Vaccine Doses, Childhood Vaccination Coverage
at 24 Months of Age, and the Health Belief Model. Public Health Reports. 2011;126(Suppl 2):135-146.
2. Rottenstreich
Y, Hsee CK. Money, kisses, and electric shocks: On the affective psychology of
risk. Psychological Science. 2001;12(3):185-190.
3. Kahneman
D. Thinking, fast and slow.
Macmillan; 2011.
4. Cappelen
A, Mæstad O, Tungodden B. Demand for Childhood Vaccination – Insights from
Behavioral Economics. Forum for
Development Studies. 2010;37(3):349-364.
5. Slovic
P, Finucane ML, Peters E, MacGregor DG. Risk as analysis and risk as feelings:
Some thoughts about affect, reason, risk, and rationality. Risk analysis. 2004;24(2):311-322.
6. Finucane
ML, Alhakami A, Slovic P, Johnson SM. The affect heuristic in judgments of
risks and benefits. Journal of behavioral
decision making. 2000;13(1):1-17.
7. Lichtenstein
S, Slovic P, Fischhoff B, Layman M, Combs B. Judged frequency of lethal events.
Journal of experimental psychology: human
learning and memory. 1978;4(6):551.
8. Medicine
Io. Adverse Effects of Vaccines: Evidence and Causality National Academies Press 2012.
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