Health professionals are preparing for the great task of vaccinating Mexican residents against Covid-19. The vast majority of us will happily take the shot, but many will choose not to.
Where does the doubt come from when authorities and doctors have repeatedly assured us that the new corona vaccines have been adequately tested?
Statistics are nonsense for many
You may think that you and your friends are intelligent, rational people. You always act according to the best knowledge you have available. But that’s not how it works.
When people have to assess potential outcomes of an action – for example, getting a vaccine – we do not look objectively at all the outcomes that may come, and then assess them based on how likely they are.
No, we weight them according to how quickly the possible outcomes pop into our heads. For example: “Can I get sick from the vaccine?”
“We use a cognitive rule of thumb: The easier it is to come up with an example of an outcome, the more likely it seems,” said Bjørn Gunnar Hallsson, psychologist and researcher at the University of Copenhagen in how humans absorb knowledge.
It is called affect bias. It means that when we have to make a decision, it matters whether an outcome is easy to imagine, because such outcomes affect our emotions much more strongly.
If you are afraid of side effects from vaccines, it may be because you can easily imagine something like the following: You get a vaccine in your arm, but it makes you very sick. It’s emotionally powerful to imagine it. Therefore, it can subconsciously play a bigger role than statistics and cold facts when making a decision.
When you are considering different consequences, it can make a big difference if one of the consequences is abstract. For instance, it can feel abstract that you would prevent others from getting sick because you receive a vaccine. That does not necessarily invoke feelings as strong as the possibility of getting sick yourself.
It feels safer to do nothing
Another psychological mechanism that affects whether or not you want to receive a vaccine is called failure bias.
Failure bias is that humans have a strong tendency to think that consequences are worse if they happen because we do something than if we fail to do something, almost as if we “asked for” something to happen because we took positive action.
Your internal clock is incorrect
Time also has an effect when deciding whether you want a vaccine.
Our evolutionary brain is trained to take gains and risks that are close to us in time much more seriously than anything that is in the future.
For example, we humans will say no to getting 20 dollars in a month instead of 10 dollars now.
For another example, if the HPV vaccine counteracts a risk of cervical cancer when you turn 50, it seems less significant than a risk of side effects now. Despite the low risk of side effects now, our brain takes that risk much more seriously than the risk of disease because the disease is out in the future.
That mechanism benefited Stone Age people, who had to take problems here and now much more seriously than the problems of the future in order to survive.
But for today’s humans, who have to decide about retirement savings, life insurance, and vaccines, the mechanism is not always as appropriate.