Less than 1% of children in the United States received no vaccines at all, according to a CDC report in 2013. Vaccine rates are generally high in the developed world, while rates of autism are in contrast, relatively low. These facts by themselves should lead most people to the conclusion that vaccines to not cause autism. It they did, the rates of vaccines should match the rates of autism. Much of the controversy began with a paper published in The Lancet in 1998. The paper has since been completely retracted and widely debunked. Despite the retraction and the vast amount of evidence supporting the safety of vaccines, many parents persist in believing their children became autistic after they were vaccinated. The cognitive bias that makes us prone to the belief that two events are related, simply due to the fact that they happened in sequence is called the illusion of causality.
Many of the vaccines are administered in the first few years of life. Parents who are convinced that vaccines caused their child’s autism cite the fact that they began to observe autistic behavior around the time they received their vaccines. This is a prime example of the illusion of causality. The child received a vaccine and then the child begins showing signs of autism, which then means that the vaccine caused the autism. The obvious flaws with this thinking is connecting these two events when the same can be done with various other things that occurred before the child began showing signs of autism. The child could have began wearing new shoes or played with a new toy. Nobody made the correlation between the autism to the new shoes, new toy, or any of the hundreds of other potential links.
The link between vaccines and autism hit the mainstream when a paper was published in The Lancet in 1998, which claimed that the MMR vaccine may be causing autism. This paper was completely retracted in 2010, after the U.K.’s General Medical Council found the authors of the paper to be “dishonest, irresponsible, and showed callous disregard for the distress and pain of children.” 10 of the original 13 authors had cosigned a partial retraction of the paper’s main interpretation in 2004. A number of studies since the publication of The Lancet paper found no link or correlation between autism and the MMR vaccine. This link between vaccines and autism can be explained by the fact that many vaccines are administered early in a child’s life. This happens to be the time of rapid development of a child where behavioral cues begin to be observed. Certain behavioral and communication cues are often the first signs of an autistic child and it becomes very easy to build a causal relationship between vaccinations and autism.
The illusion of causality plays a huge role in not only the vaccine debate, but our general ability to let go of old beliefs, even in the face of new contradicting information. Various studies have shown that not only does the illusion of causality encourage us to find links between two unrelated events, they prevent us from correcting causal illusions with new information. A study by Brendan Nyhan, a political scientist at Dartmouth, presented 1,759 participants various facts about the effectiveness of vaccines. The study found that even after being exposed to positive information supporting vaccines, the participants were no more likely to vaccinate their children. Additional studies are finding that being presented new information is simply not enough to change people’s minds. To break the illusion of causality, efforts need to be made to not just present facts and new information, the underlying reason why we think a certain way needs to be explained. Once we established the causal illusion to be true, it takes a great effort to let go of our original belief. This is why even unequivocal facts are sometimes not enough to convince someone the fallacy in their beliefs.
Most of us would like to believe that we’re all completely rational and that given a set of facts, we could all have our minds changed, even for those ideas that we’ve deeply believed in for a long time. The reality is that all of us are susceptible to various biases and the illusion of causality is the simplest one that we all have experienced on a daily basis. One event happens right after the other and it just makes sense to believe that one caused the other, when they most likely are unrelated. Studies are finding that not only does this bias occur, but it’s also very difficult to overcome once it is established in our minds. To overcome this, it goes beyond being presented new information to dispute the causal illusion. For us to overcome some of the causal illusion, we must understand the mechanism in which illusions of causality occurs.