The COVID-19 pandemic is unlike anything that most of us have seen in our lifetimes. The virus is more easily transmissible than the flu, it has a higher mortality rate, and there is currently no vaccine to protect us against it.

In April, hundreds gathered in Sacramento to protest shelter-in-place rules. © Josh Edelson / AFP via Getty Images

As such, behavioral change is our means of defense. Health organizations from around the world have unanimously recommended self-quarantining and social-distancing practices in order to mitigate the spread of the disease. Although these measures are effective in guarding against pathogens and infectious disease, they are not easy. Social isolation can be painful. Even the most introverted among us require some social interaction.

Foiling our affiliative needs has consequences for both our physical and psychological well-being. However, quarantine has social consequences, as well—ones that reveal a great deal about how we humans respond to the threat of infectious diseases. Physical distancing may be a natural reaction to infectious disease, but it can unfortunately give rise to some of the ugliest human tendencies: partisanship, prejudice, and xenophobia.

Activating our biological and mental security systems

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The physiological immune system is an example of an evolved solution to infectious disease. It is analogous to a security system. When an infectious agent enters our body, the immune system attempts to identify and remove the intruder.

As crucial as the physiological immune system is, it is not our only defense against infectious agents. We also have a set of prepared psychological responses that are believed to promote disease avoidance. One of them is disgust, a universal human emotion identifiable in all cultures. Disgust is responsible for the revulsion that you experience when you taste sour milk or the nausea that you experience when you hear somebody clear phlegm from their throat. Its function is to encourage us to avoid potentially contaminated objects and people, thus preventing entrance of pathogens into our bodies.

However, the behavioral immune system is not always accurate. Just as a smoke detector may go off when there isn’t a fire, disgust can be triggered when there isn’t an infectious agent. Evolution doesn’t provide us with a window to the truth; it’s concerned with error management. It is in the business of minimizing the probability of costly errors (like ingesting infectious agents). The result is that we are prone to magical thinking when it comes to contamination. For example, if someone were to write “cyanide” on an unopened bottle of water and offer it to us, we would have difficulty drinking it even though we knew that it wasn’t really poison. Why take chances? Our behavioral immune systems are stubborn bodyguards who will sacrifice truth for survival.

This finicky disease-avoidance system has important implications for the way that we think and the way that we interact with others. As Francis Bacon pointed out, our mind is “a crooked mirror.” We don’t see things for what they are. We are vulnerable to certain beliefs, and we unconsciously and unintentionally seek out information that supports those beliefs (we have a “confirmation bias”). Imagine a detective coming to your door and informing you that your mother has been arrested for murder. How much evidence would it take for you to believe that she was guilty? Would you need fingerprints? DNA? Video footage? Would that be enough? If a stranger was the suspect, would you hold them to the same standard of evidence? Not likely.

In short, your mother is one of US and the stranger is one of THEM. Humans are categorical thinkers. We construct Dr. Seussian worlds that are populated with THISs and THATs. The labels we apply to things provide us with structure and enable us to distinguish between things. Our categories also provide us with predictability, and humans desire a world that is stable and predictable. If we know that an organism is a CAT and not a DOG, we know that the organism most likely meows—and so we’d be quite surprised if the CAT barked.

Just as we categorize non-human animals (like CATs and DOGs) and objects (like THISs and THATs) in our environments, we also categorize ourselves and others. We divide people into USs and THEMs. We are so prone to social categorization that when we are randomly assigned, by the flip of a coin, to wear a particular color shirt (like red vs. blue), we will exhibit ingroup bias. We will favor and share our resources with those who have the same color shirt as us because we naturally assort into groups. We prefer friends and partners who share our characteristics, beliefs, and attitudes.

Though we generally prefer a structured and orderly world, the world we live in is actually quite messy. Things don’t often fit conveniently into the socially constructed categories of THISs and THATs. People don’t fit conveniently into the categories of USs and THEMS. What happens when these lines become blurred, when categories become contaminated?

When categories get confused

In a classic 1927 study described by Ivan Pavlov, dogs were rewarded with food when presented with a figure of a circle. As you would expect, they quickly became fond of the circle. The dogs were then presented with an oval and were not rewarded. The dogs quickly learned to discriminate between the circle and the oval. However, once the experimenter tampered with the oval to make it look more and more like the coveted circle, there was a point at which the dogs could no longer discriminate between the stimuli. When presented with the ambiguous stimulus, not quite a circle but not quite an oval, the dogs did not know how to respond. The dogs’ predictive model failed. The dogs began to act erratically, squirming and squealing.

The desire for predictability and categorical certainty is not particular to dogs. We all suffer from it to varying degrees. Some of us are so fastidious that we develop obscure phobias like brumotactillophobia, the fear of foods touching. Though most of us aren’t quite as orderly as brumotactillophobes, we do generally prefer some sense of tidiness. We sort our silverware and our laundry and we get frustrated when we can’t locate a sock’s partner. As the aphorism goes, there is “a place for everything and everything in its place.”

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Infectious disease may hold the key to understanding our orderly nature and our tendencies to categorize things as THISs and THATs and people as USs and THEMs. Like us, the microorganisms (bacteria, viruses, etc.) that cause infectious disease are in the business of survival and reproduction.

Unfortunately for us, their reproductive strategies can involve hijacking our bodies and commandeering our resources, which can interfere with our own abilities to survive and ultimately reproduce. As a consequence, humans and infectious microorganisms are locked in an evolutionary arms race. Infectious diseases have been developing more and more effective ways to break into our bodies, and we have been evolving more and more complicated security systems to keep them out.

In times of turbulence and uncertainty, when our lives are threatened, we have an even greater desire for certainty. We seek out information that provides us with affirmation and avoid ideas and people that we believe are dangerous. This may be particularly true when there is a disease threat.

Infectious agents can capitalize on our social behavior. They can manipulate our bodies into sneezing and coughing, which are convenient ways to propel themselves to other hosts who are in close proximity. Indeed, one of the most common routes of disease transmission is person-to-person contact. As such, the behavioral immune system encourages us to be cautious about social interactions. We prefer people who look like US and think like US. If we are liberals, our friends and partners tend to be liberals. If we are conservatives, our friends and partners tend to be conservatives. This assortative sociality, selecting friends and partners based on similarity of physical and psychological characteristics, is exaggerated when disease threat is high.

Some of the key facial characteristics of our expression of disgust are a protruding tongue, raised upper lip, and a scrunched nose, which are all consistent with the potential ingestion of a contaminant. Disgust, however, also results in a lowered brow, an almost squint. This is the same type of ocular expression that you might see in a coin collector who is trying to make a distinction between a “fine” coin and a “very fine” coin. Just as a coin collector sifts through coins, disease threat causes us to make fine-grained distinctions between USs and THEMs. In areas of the world where there are more types of infectious disease and more life lost to infectious disease, we tend to be more socially exclusive. We divide ourselves into smaller and smaller subgroups. We cordon ourselves off from outside social interaction. The USs and THEMs become better defined.

When fear becomes hate

This cultural quarantining is nature’s way of stemming the spread of infectious disease, but it has a nasty side effect. It fosters prejudice and xenophobia. When we are primed with a disease threat, we become more prejudiced toward outgroups.

The COVID-19 pandemic began in Wuhan, China. In a tweet on March 16, President Trump referred to COVID-19 as the “Chinese virus.” A week later, he attempted to mitigate the damage by tweeting, “It is very important that we totally protect our Asian American community in the United States, and all around the world. They are amazing people.” On March 23rd, however, Trump tweeted, “THIS IS WHY WE NEED BORDERS!” While border policies are always a matter of debate, the president’s inconsistent messages may be helping to fuel hate crimes against Asian Americans. Russell Jeung, a professor of Asian American Studies at San Francisco State University, created a website to track these incidents. Within one month of its official launch, they have catalogued nearly 1,500 incidents of discrimination against Asian Americans across the country.

Social media platforms are not immune to the effect that infectious disease has on our social behavior and beliefs. In the time of COVID-19, we gravitate to social media to get our affiliative fix. It provides us with virtual social comfort in this time of physical social isolation.

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There is, however, a risk: Social media platforms can become echo chambers. Just as disease threat causes us to be cautious with our social interactions, it makes us cautious about the ideas that we expose ourselves to. We follow people who share our beliefs and block the people who offend us. As a consequence, our social media platforms can become breeding grounds for conspiracy theories. The result is that we become more and more polarized.

Ironically, this polarization can backfire. It can make us more vulnerable to infectious disease. For example, those who are more sensitive to disgust and are germ-averse are more likely to hold anti-vaccination attitudes.

All of these psychological forces have converged during the COVID-19 pandemic to generate some dangerous trends. Social-distancing practices have become politicized. Political figures have occasionally refused to self-quarantine and wear face masks at politicized events.

Importantly, the conspiracy theories that are emerging during the COVID-19 pandemic are not limited to a particular political party. Anti-vaccination groups in California are protesting the social-distancing practices and are concerned that the government is conspiring to inject the world’s population with infected vaccinations. Likewise, conservative groups who are concerned with constitutional liberties are protesting the social-distancing practices in Pennsylvania and Michigan because they believe that the government is using fear to exert control and take our freedoms and our guns.

If we are not careful, the polarization and resulting misinformation surrounding COVID-19 will result in more lives lost. Indeed, early evidence suggests that media figures who have downplayed COVID-19 have had elevated cases of the virus among their viewers.

In our fight against COVID-19, we are walking a tightrope. On one hand, we must engage in social distancing and limit social interaction so that we can mitigate the spread of this disease. On the other hand, we need to recognize that these steps can evoke some of the ugliest social behavior in humans, splitting us into antagonistic camps. The truth is that COVID-19 is a non-partisan, global, human problem. We won’t stay healthy by turning on each other.

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