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Why the Human Brain Is Designed to Distrust

Conspiracy theories come naturally.

What kind of person would have so little trust in his fellow man to believe that the U.S. president and the CIA conspired to fake the death of Osama Bin Laden, or that the news media is tightly controlled by a powerful cadre of wealthy extremists? If you peruse the psychological literature on belief in conspiracy theories, or read political commentaries on the topic, you’ll hear a lot of talk about paranoia, alienation, and anomie. You’ll learn that people who believe in one bizarre conspiracy theory are also likely to believe in others (it’s all connected to illuminati and the Kennedy assassinations, after all). You’ll find out that conspiracy beliefs have been linked to being poor, being a member of a downtrodden minority, having a general sense that one’s life is controlled by external factors, and other unfortunate circumstances.

But there’s another perspective that stems from thinking about the evolutionary background of our species: The human brain was designed for conspiracy theories. On this view, we’re all conspiracy theorists–you, me, and your aunt Ginger in Iowa.

Let’s put aside the particulars of the wacky conspiracy theory du jour, and consider this: Some alleged conspiracies have turned out to be quite real–Al Qaeda, the CIA, the KGB, and the Mafia have all involved real people getting together to plot real nefarious deeds. Just because you’re paranoid doesn’t mean they aren’t out to get you. As evolutionary theorists such as Robert Trivers and Bill von Hippel have observed: a serious down side of communication is that it opens the doors for deception (Is that a tasty worm or an angler fish’s trap? Is the killdeer really injured or faking it?). Human beings are especially talented communicators, and pretty good deceivers as well. Researchers who study the psychology of lying find not only that the average person lies about something every day, but that we can’t do that much better than chance at distinguishing a prevarification from a truthful statement.

Our ancestors had to worry about plots by members of their own group as well as plots by members of other groups (who had even less to lose and more to gain from doing them harm). Evolutionary psychologists such as Pascal Boyer and Ara Norenzayan have noted that the human brain has powerful mechanisms for searching out complex and hidden causes. The popularity of Sherlock Holmes, James Bond, and Harry Potter owed much to their authors’ talents for exercising those causal mechanisms in readers.

And as evolutionary psychologists Randy Nesse and Martie Haselton have argued, the mind is designed like a smoke detector, set to go on red alert at any possible sign of threat in the environment (rather than waiting till the evidence is so overwhelming that it is too late to put out the fire). Once we have accepted a belief, we have a host of cognitive mechanisms designed to bias us against rejecting it. One of my favorite such studies was done at Stanford psychologists Charlie Lord, Lee Ross, and Mark Lepper. They presented their very bright students with a careful balance of scientific evidence for and against the benefits of capital punishment. After hearing that balanced evidence, the students who initially favored the death penalty were even more convinced they were right, whereas the antis became even more convinced in the opposite direction. What happened was that students selectively remembered weaknesses in the other side’s argument, and strengths of the evidence favoring their own side. Sound familiar? (and remember, these were Stanford students, not members of an extremist group holed up outside Two Dot, Montana).

What about the research showing that people in downtrodden groups are more prone to conspiracy beliefs than those of us reading the New York Times in some upper middle-class suburb? Those findings point out another feature of our evolved psychology–our brains turn up the volume on our danger systems when we are under threat. Research from our labs has shown that people who are feeling self-protective (after seeing a scary movie) are more likely to project anger onto the faces of strange men from other groups, and research by Mark Schaller and his colleagues finds that being in a dark room amps up specific kinds of stereotypes (those involving the dangerousness of Arab or African-American men). To the extent that one’s life involves daily threats and dangers, one is likely to be watching for signs of danger lurking out there.

By saying that the human brain is designed to be on the alert for conspiracies, and that there have always been real conspiracies out there, do I mean to imply that there’s nothing we can do to avoid believing the next story we hear about the plot involving Obama, the AMA, and the Roman Catholic Church? No. Charlie Lord and his colleagues found that Stanford students could be a bit more objective if they first asked themselves the simple question: “How would I feel if this same evidence supported the exact opposite conclusion?” Rutgers Sociologist Ted Goertzel has studied beliefs in conspiracy theories for two decades, and he has a couple of additional bits of advice for those who wish to “distinguish between the amusing eccentrics, the honestly misguided, the avaricious litigants and the serious skeptics questioning a premature consensus.” First, look for “cascade logic”–reasoning that requires believers to implicate more and more people in the conspiracy whenever anyone reports evidence against their claims (aha, they’re in on it too!). Second, be skeptical of claims that require unrealistic amounts of power and control on the part of the conspirators. Goertzel gives the example of the alleged conspiracy to fake the moon landing, which would have required complete complicity by thousands of scientists and technicians working on the project, as well as all the media covering the events, and even the scientists in other countries (including Russia) who tracked the events. Of course, it is possible that CIA commissioned this article, and I’m saying all this to throw you off the scent.

Douglas T. Kenrick is the author of Sex, Murder, and the Meaning of Life: A psychologist investigates how evolution, cognition, and complexity are revolutionizing our view of human nature. The book was recently chosen as a monthly selection by Scientific American Book Club. He claims to have no connections to the illuminati.


Abalakina-Paap, M., Stephan, W. G., Craig,T., & Gregory, W. L. (1999). Beliefs inconspiracies. Political Psychology, 20,637–647.

Atran , S. , & Norenzayan , A. ( 2004 ). Religion’s evolutionary landscape: Counterintuition, commitment, compassion, communion . Behavioral and Brain Sciences, 27 , 713 –770.

Boyer, P. (2003). Religious thought and behavior as by-products of brain function. Trends in Cognitive Science, 7, 119-124.

Nesse, R. M. (2005). Evolutionary psychology and mental health. In D. Buss (Ed.), Handbook of evolutionary psychology (pp. 903–930). Hoboken, NJ: Wiley.

Haselton, M. G., & Nettle D. (2006). The paranoid optimist: An integrative evolutionary model of cognitive biases. Personality and social psychology Review, 10, 47–66.

Lord, C. G., Lepper, M. R., & Preston, E. (1984). Considering the opposite: A corrective strategy for social judgment. Journal of Personality and Social Psychology, 47, 1231–1243.

Lord, C. G., Ross, L., & Lepper, M. R. (1979). Biased assimilation and attitude polarization. Journal of Personality and Social Psychology, 37, 2098–2109.

Schaller, M., Park, J. H., & Mueller, A. (2003). Fear of the dark: Interactive effects of beliefs about danger and ambient darkness on ethnic stereotypes. Personality & Social Psychology Bulletin,29, 637–649.

Goertzel, T. (2010). Conspiracy theories in science. EMBO reports, 11, 493-499.

von Hippel, W. & Trivers, R. (2011). The evolution and psychology of self- deception. Behavioral and Brain Sciences, 34, 1-16.

Image source: Take Chicagoist’s Obama Conspiracy Theory Quiz.

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