Will that depression rub off on me? How beliefs about mental illness influence our interactions

If people’s memory for past events was entirely accurate and if people could only act on things they remembered, our ability to survive in the world would be severely curtailed. This may sound provocative (it is) and counter-intuitive (it is) but it’s also commonly accepted as true.


Because if all you remembered about certain four-legged furry animals were the particular dogs that you have seen in your life—that is, your beloved Fido from your childhood plus the neighbors’ dogs and so on—then you wouldn’t be able to predict that this new dog that just leaped over the fence in front of you might bark at you (or wag its tail, if it feels so inclined). This process of abstraction that enables us to recognize a furry animal as a dog, and predict how it might act even if we have never seen it before, is known as categorization.

According to Dr Jessecae Marsh, “the knowledge we hold about categories allows us to make this jump from how we think about a member of a category to actually deciding whether to interact with that category member.”

In a recent paper published in Memory and Cognition, a journal of the Psychonomic Society, Marsh and co-author Lindzi Shanks asked what determines people’s interactions with a particular type of category, namely mental illness categories.

Despite the prevalence of mental illness—almost 50% of Americans will experience symptoms severe enough to warrant a mental disorder diagnosis at some point in their lifetime—people vary greatly in their willingness to interact with others diagnosed with a mental illness. Given that stigmatization of people with mental illness makes it more difficult for them to get healthy, it is particularly important to understand what factors determine whether others interact with—or shy away from—people with mental-health issues.

Marsh and Shanks investigated two classes of factors: Beliefs about how one develops a mental illness and beliefs about the underlying reality of mental disorders. The former is particularly interesting because it revolves around the question whether people believe that an illness can be contracted from interactions with those who have that illness. In other words, is mental illness “contagious”?

It is already known that people are unwilling to interact with patients who are diagnosed with communicable medical disorders—the tragic Ebola outbreak at the time of this writing is a case in point—but does this also apply to mental illnesses? And how could it, unless people—mistakenly—believed that depression might be passed on through, … what exactly, a sneeze? This possibility is not entirely far fetched, given that people can hold unbelievable contagion beliefs, such as acting as if the attributes of an evil person could be attained by wearing a sweater he owned.

In their studies, Marsh and Shanks presented participants with a list of psychological disorders (such as alcohol disorder or autism) and medical disorders (such as breast cancer or hepatitis) and asked participants to indicate how likely they thought it would be for someone to catch this disorder “through close contact with someone with that disorder.” The results showed that while medical disorders were thought to be communicated primarily through physical contact, for mental illnesses participants thought that social interactions could, over time, transmit that disorder to another person. According to Dr Marsh, people seemed to believe that for certain mental illnesses “interacting with someone with the disorder could allow you to ‘catch’ that person’s mental illness.”

In a further study Marsh and Shanks showed that the main driver of willingness to interact with people with a disorder was communicability: The more a disorder was believed to be communicable, the less participants were willing to interact with its members. So if others around you think that your depression might “rub off” on them through social interaction, they will likely avoid you.

Intriguingly, willingness to interact was also influenced by the presumed cause of a mental illness: The more psychologically or environmentally based a disorder was believed to be, the less willing people were to interact with its members. Marsh and Shanks are currently following up on this relationship between contagion beliefs and believing a disorder is psychologically or environmentally caused.

At first glance, this result might appear puzzling: Why would it matter how one’s mental illness was caused when it comes to others making decisions about social interactions? On closer analysis, however, this is not a unique phenomenon limited to mental illness: Consumers pay far less for “industrial” diamonds that are chemically identical to natural diamonds than “real” diamonds that are dug out of the ground. Similarly, people are prejudiced against genetically-engineered foods even if they are indistinguishable from foods obtained by conventional Mendelian techniques.

People value how things came to be, and this affects our judgments in a wide variety of circumstances. And when it comes to mental illness, how we treat people with disorders depends on how we think their illness came to be. Dr. Marsh notes “it is important to understand these beliefs about contagion and what it makes us think about mental disorders because given the prevalence of mental illness, odds are these beliefs may eventually color how we see our own loved ones or ourselves.”

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