Friday, November 1, 2019

The Anti-Vaccine Movement and Cognitive Biases

A major public health crisis has developed in this country because many parents wrongly believe that measles-mumps-rubella vaccines cause autism. This falsehood has caused a serious outbreak of measles in several parts of this country. This year (as of March 12), there has been at least 228 reported cases of measles, a potentially lethal disease, in the United States. WHO recently declared the anti-vaccine movement a top 10 health threat because of unnecessary measles outbreaks in several countries.

The anti-vaccine movement began in 1998 with a now withdrawn paper by discredited doctor Andrew Wakefield, which claimed a connection between childhood vaccinations and autism. Since the paper’s publication, numerous studies have confirmed the safety of MMR vaccines, while none have supported the paper’s conclusion.

Yet many parents, advocates, and professionals continue to claim that the MMR vaccine is unsafe. Why? The answer is cognitive biases–thinking errors that influence human decision-making and judgment. Copious information on the safety of vaccines by doctors, scientists, and the mass media has not been enough to eliminate the pernicious influence of the anti-vaccine myth. The public must be educated on how cognitive biases work and how they affect thinking to eliminate the anti-vaccine myth.

Cognitive scientists have made enormous advances in understanding how the human brain works, including how humans make cognitive errors. Human brains evolved just as physical characteristics did. Consequently, many of humans’ thinking processes developed for survival in primitive times. This process produced ways of thinking that are different from reality--cognitive biases.

According to Daniel Kahneman, humans use two types of thinking. System 1 is intuitive thinking, which operates automatically and controls the details of our lives, such as walking, eating, and driving. System 2 controls tasks that require conscious decision-making, such as buying a house, running a business, deciding whether to launch missiles. Cognitive biases occur when thinking relies uncritically on System 1 (intuition). So, anti-vaccinators are relying on their intuitions, which are unreliable, rather than conscious judgement, which is much more likely to reach the right conclusion.

The most important bias for the anti-vaccine myth is illusory correlation–assuming a connection between two unrelated events. (The individual perceives a cause and effect relationship when there is none.) With the autism myth, someone sees that a child with autism was vaccinated so she assumes that the vaccination caused the autism without any proof of a connection. This is like ancient man believing that a human sacrifice brought much needed rain.

Under the confirmation bias, people focus only on information that supports their position. For example, a person mentions five studies supporting her position, but ignores the ten studies that don’t. People also ignore faults with the studies that support their view. Anti-vaccinators only look for evidence that supports their position. In addition, this “evidence” is not based on scientific research, but on rumors and falsehoods.

Similarly, the Semmelweis reflex causes individuals to reject evidence that contradicts a strongly-held idea. Most Renaissance thinkers rejected Galileo’s observations because they were inconsistent with their strongly-held notion that the universe revolved around the Earth. Anti-vacinators ignore the avalanche of scientific evidence that demonstrates the safety of MMR vaccines because it contradicts their views on vaccines and autism.

Emotional reasoning was also important in creating the anti-vaccine myth. Emotional reasoning is allowing emotions to affect one’s interpretation of reality. Parents’ understandable need to protect their children caused them to let their emotions affect how they viewed vaccines.

Finally, the bandwagon effect helped spread the anti-vaccine myth. The bandwagon effect is the propensity to believe something because many other people do so. Social media has created a bandwagoning effect for the anti-vaccine myth.

How can we overcome cognitive biases, like those that created the anti-vaccine myth? First, many researchers believe just having knowledge of cognitive biases reduces their frequency. Second, slowing down one’s thinking can eliminate cognitive errors. With important decisions, you should check your System 1 intuitions with your System 2. Consider all evidence, even that which contradicts your ideas. Separate the objective from the subjective and avoid lazy thinking. Critically consider all reasonable alternatives. Add reflection and self-monitoring to your thinking processes. Create problem-solving strategies. Be able to explain your reasoning process. Consider the consequences of making a mistake. Third, don’t let emotions alter your thinking. Evaluate whether your decision is based on emotion or System 2 thinking. Fourth, understand that just because two events are connected in time does not mean that one event caused the other. Finally, exercises exist to help people overcome their cognitive biases.

It is tragic when parents learn their child is autistic. However, it does no good to blame the wrong cause (vaccines). The anti-vaccine myth only creates more problems by helping the spread of dangerous diseases.

(Scott Fruehwald)


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