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The Surprisingly Deep Roots of Mental Immunity Research

Evidence of the mind’s immune system goes back seventy years.

Key points

  • Mental immune systems have been hiding in plain sight for decades.
  • Research in the 1950s uncovered their existence.
  • A paradigm shift is under way and it could revolutionize our ability to combat cognitive contagion.
  • The mind's immune system can be boosted, making it more resistant to misinformation.
Rob Schreckwise / Unsplash
Psychologists have been thinking about immunity to misinformation for a long time.
Source: Rob Schreckwise / Unsplash

Want to understand the roots of our crazy, mixed-up, post-truth world? Care to be part of the solution? The key, on both counts, is to understand how the mind’s “immune system” works.

Here’s the idea: The mind has infrastructure for filtering information. This infrastructure functions like the body’s immune system: When working properly, it screens out the bad stuff — false, misleading, and dysfunctional ideas — and lets in the good stuff, ideas that are accurate and useful.

We can study mental immune systems the same way we study other natural systems. We can learn how they work and why they fail. We’ve neglected and abused mental immune systems for decades. And social media subjects them to unusual stress. That’s why so many minds struggle today to fight off astonishingly irrational ideas: Our culture’s immune system, its ability to filter out misinformation, has been compromised.

Research on mental immune systems goes back to the 1950s. In a series of important but little-known experiments, psychologist William McGuire showed that exposure to a weakened form of a persuasive argument confers a kind of resistance to stronger versions of the same argument. He was struck by the analogy with inoculation. (Immunologists inoculate our bodies by exposing them to weakened forms of dangerous pathogens, and our bodies respond by developing immunity to stronger versions of those same pathogens.) He didn’t put the point in just this way, but he’d uncovered the first hard evidence of the mind’s immune system. He labeled his findings “inoculation theory.”

McGuire essentially showed that ancient rhetorical tricks (like “straw man” argumentation) can induce immunity to new information, even if the new information is valid. Put differently, bad actors can use these kinds of inoculations to “hack” mental immune systems. And this is exactly what ideologues, aspiring demagogues, cult leaders, and conspiracy theorists do: hack mental immune systems and manipulate minds.

In the 2000s, a new generation of inoculation theorists began asking a different question, namely: How do we inoculate minds against misinformation? Can we prevent people from becoming science deniers or conspiracy theorists? If so, how? Experimentalists like Sander van der Linden, John Cook, and Stephan Lewandowsky have made important discoveries in this area. We now know that misinformed belief tends to be resistant to change. In fact, a mind’s immune system will mobilize to protect misbelief — sometimes by “attacking” the better information that threatens to replace it.

The good news is that it’s possible to inoculate minds against bad ideas. If good information gets there first, it can make a mind more resistant to bad information that arrives later. Studies show that raising awareness of the motives behind the peddling of misinformation can help to inoculate people against the misinformation they peddle. This process may also involve:

  1. stressing that there’s a scientific consensus on (say) climate change
  2. exposing flawed argumentation, or
  3. helping people understand that cherry-picked information can be used to make almost anything look plausible

A research team led by Gordon Pennycook has shown that believing that one’s beliefs should change in response to evidence is highly correlated with mental immune health. More precisely, Pennycook’s team has shown that when people lose this “metabelief,” they become more susceptible to extremist ideologies, conspiracy thinking, science denial, et cetera. In Mental Immunity, I argue that this metabelief is the linchpin of the mind’s immune system. My “damaged fulcrum model” posits that attacks on the norms of accountable talk can profoundly compromise cognitive immune systems, leading to destructive outbreaks of unreason.

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