The human brain is a frustrating thing. On the one hand, it has the analytical power to do the science, to develop the tests and treatments and vaccines we need to stop pandemics. On the other hand it’s often irrational and makes us think and act in ways that help the virus spread. 

Here are four of those cognitive biases that have made pandemics worse.  

1. Exponential Growth Prediction Bias

We humans tend to underestimate a disease’s ability to spread. We intuitively process “growth” as linear. If one thing happens today, and one thing happens tomorrow, then we assume that another thing will happen the next day and by the end of a month, thirty things will have happened. But infections like COVID-19 can spread exponentially, so if one person is sick today and another gets sick tomorrow, the day after tomorrow, four people could get sick, and by the end of the month, millions of us could be sick. The difference between the both is huge and it is the reason why many of us cannot imagine that we need to take such strict precautions. What’s more, our biased brains not only underestimate the risk of any person getting sick – we also underestimate the chances that that one person is us!

 2. Optimism Bias

 Ideally, in pandemics everyone should act pessimistically – like they are likely to get infected (or already are) – but that kind of thinking does not come naturally to us. Humans are by nature; optimists. Evidence shows that we think we are above average as far as intelligence, and less likely than average to get in a car accident. So it is no surprise that many people underestimate their likelihood of getting COVID-19 and act accordingly. The problem is, this optimistic behaviour, when taken by lots of people, causes the virus to spread more quickly.


3. Hyperbolic Time Discounting Bias

 We humans also have a bias against our future selves. We are generally able to take stock of things and decide that temporary inconveniences like steering clear of each other outweigh temporary pleasures like not steering clear of each other can help stop pandemics. But, in the moment, our brains’ desire for instant gratification means that we sometimes justify things that we want, even if that screws over “future us.” 


4. Reactance Psychology

 Finally, we humans do not like being told what not to do. Especially, when we hear from an authority, “Don’t see your family,” or “Don’t leave your house without a mask,” the primitive parts of our brains sense a threat. We get mad and become likely to do the opposite, even when we know the guidelines will help limit the spread of disease. This effect is especially strong in places where “me” is valued over “we.” Even worse, once our hackles are raised, we are more likely to buy into dangerous misinformation. 

 Luckily, we humans have also identified some way to combat our misguided instincts. Studies have found that regular reporting on the spread of the disease has helped people estimate risks and positive reinforcement from friends and family has helped people stay the course. So perhaps the rational parts of our brains could be the key to fighting the irrational parts of our brains. In other words, that which can fight viruses can also fight biases.