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Is the government covering up evidence of alien landings? Are powerful elites plotting a New World Order? Is a hoax? Are vaccines really the government's attempt at mass mind-control? Are lizard people taking over the planet?

There seems to be something inexplicably compelling about the nature of conspiracy theories—more than 50% of Americans believe in at least one. You might think that even though substantial minorities of people endorse these seemingly eccentric beliefs, conspiracy ideation is mostly harmless fun, food for those who are palpably out of touch with reality.

Think again.

In a new study, I find that mere exposure to a popular conspiracy theory can make you less pro-social—and less likely to accept established scientific principles.

In the experiment, I instructed people to watch a short two-minute video clip of a popular global-warming conspiracy movie. I randomly assigned people to one of three groups:

a) a "conspiracy" group, whose members watched the clip

b) a group that watched an "inspirational" United Nations video about taking action on global warming instead

c) a "neutral" control group.

Results clearly showed that those participants exposed to the conspiracy video were:

less likely to think that there is widespread scientific agreement on human-caused climate change. less likely to sign an online public petition to help stop global warming. less willing to donate or volunteer for a charity in the next six months.

I have termed this phenomenon the "conspiracy effect."

These findings are troubling. Consider the fact that 97% of leading climate scientists have independently concluded that human-caused global warming is real and happening. Yet, just watching a two-minute clip about how it all might be part of a global conspiracy appears to be enough to compel us to dismiss science and make us feel less inclined to engage with important societal issues in general, including helping others in need.

You might think, "Oh well, that's just global warming," (only the single most existential threat of our time).

Think again.

Other recent research has shown that belief in conspiracy theories is associated with the motivated rejection of science, i.e., denial of the other established scientific facts such as the link between HIV and AIDS, or between and lung cancer. Similarly, research has shown that reading about popular vaccination conspiracy theories can make people less willing to vaccinate their children, which poses a major public health risk. Refusing vaccinations based on belief in unproven conspiracy theories is not very pro-social; it means you are unnecessarily putting other children at risk of catching otherwise preventable life-threatening diseases.

The list does not end here. The spread of influential conspiracy propaganda can have serious societal consequences. For example, belief in some conspiracy theories has been associated with , right-wing extremism, racist attitudes against minority groups (e. ., anti-Semitism) and even political violence.

Most of these studies report associations for those who already believe in conspiracy theories. My experiment, however, illustrates that some of these effects might in fact apply to anyone after merely being exposed to a conspiracy theory.

I have written about the psychology of conspiracy theories before, yet I want to clarify an important point: Psychologists who study conspiracy theories do not investigate whether or not a particular conspiracy theory is true. Rather, we are interested in the social consequences and the psychological nature of widespread conspiracy ideation.

Moreover, it is a mistake to assume that these type of studies imply that believing that someone is conspiring against you means you must be crazy. That's not what this line of research suggests. Clearly, people and governments have conspired against each other, throughout human history. Healthy skepticism lies at the very heart of the scientific endeavor. Yet there is something fundamentally dangerous and unscientific about the nature of conspiracy theorizing. Here are two reasons it can be problematic:

1. It's never just about one conspiracy.

Conspiracy theorists rarely simply endorse a single conspiracy theory. Rather, belief in one often serves as evidence for belief in others, and this quickly turns into a worldview, i.e., a lens through which we view the world, with new information about world events processed not according to the weight of the evidence but rather in terms of how consistent it is with one's prior convictions. For example, studies have shown that people who believe in conspiracy theories often espouse mutually contradictory explanations about the same event, and are even eager to endorse entirely made-up conspiracy theories. In sum, it's not really about the actual evidence anymore, but rather about whether a theory is consistent with a larger conspiratorial worldview.

One reason people fall prey to conspiracy-mindsets is because of a reasoning error known as the "conjunction fallacy"—the tendency to think that specific events are more likely than general ones.

For example, which of the following do you think is more likely?

(A) 9/11 was an inside job

(B) Global warming is a hoax

(C) 9/11 was an inside job and global warming is a hoax

People are easily swayed by option C due to the false representativeness of the two events (i.e., they are both examples of conspiracy theories so they seem plausible when paired together). Yet, the undeniable laws of probability state that the likelihood of two independent events (i.e., their "conjunction" ) is always less likely (or equal) to the probability of either event (A) or (B) being true by itself. In other words, the more conspiracies one endorses, the less likely it is that they are all true at the same time.

2. The premise of (most) conspiracy theories is inherently unscientific.

You should be skeptical of any theory that starts out with the exact same premise every time: Some malevolent and ill-intentioned individual, group, or organization is somehow out to get you.

It is not wrong to have a hypothesis. What is suspicious, however, is when that hypothesis never changes. The interesting thing about conspiracy theories is that they start out with the need to confirm a particular premise (i.e., some evil actor must be responsible). This is what psychologists refer to as a fundamental attribution error—the tendency to overestimate the actions of others as being intentional rather than simply the product of (random) situational circumstances.

Unfortunately, many of us are uncomfortable with the notion of randomness, because it lacks meaning. The only thing it communicates to people is uncertainty and a lack of agency and control over what is happening in the world. It is easier, and much more comforting, to simply point our finger at someone. Conspiracy theories, therefore, serve an important role—they restore a false sense of certainty and control.

In contrast to scientific theories, conspiracy theories are also not revised or updated in light of new evidence. If there was evidence that something happened not because of some evil plan, but rather, simply because of an accident, a conspiracy theory is still unlikely to be revised. Instead, the evidence is rejected, usually on the basis that it must be part of the conspiracy. In short, conspiracy theories have a tendency to form a closed network of false beliefs that mutually support each other.

Source: DreSmith/DeviantArt

My advice: Misinformation spreads quickly and can do much more harm than you think. The next time someone tries to convince you of a popular conspiracy theory, beware of the conspiracy effect.

Further Reading

Abalakina‐Paap, M., Stephan, W. G., Craig, T., & Gregory, W. L. (1999). Beliefs in conspiracies. Political Psychology, 20(3), 637-647.

Darwin, H., Neave, N., & Holmes, J. (2011). Belief in conspiracy theories. The role of paranormal belief, paranoid ideation and schizotypy. and Individual Differences, 50(8), 1289-1293.

Jolley, D., & Douglas, K.M. (2014). The effects of anti-vaccine conspiracy theories on vaccination intentions. PLoS ONE 9(2), e89177.

Lewandowsky, S., Oberauer, K., & Gignac, G.E. (2013). NASA faked the moon landing—therefore, (climate) science is a hoax: An anatomy of the motivated rejection of science. Psychological Science, 24(5), 622-633.

Oliver, J.E., & Wood, T.J. (2014). Conspiracy theories and the paranoid style (s) of mass opinion. American Journal of Political Science, 58(4), 952-966.

Sunstein, C. (2014). Conspiracy Theories and Other Dangerous Ideas. New York, NY: Simon & Schuster.

Swami, V. (2012). Social psychological origins of conspiracy theories: the case of the Jewish conspiracy theory in Malaysia. Frontiers in Psychology, 3, 280.

van der Linden, S. (2013). What a Hoax: Why people believe in conspiracy theories. Scientific American Mind, 24(4), 40-43.

van der Linden, S. (2015). The conspiracy-effect: Exposure to conspiracy theories (about global warming) decreases pro-social behavior and science acceptance. Personality and Individual Differences, 87, 171-173.

Wood, M.J., Douglas, K.M., & Sutton, R.M. (2012). Dead and alive beliefs in contradictory conspiracy theories. Social Psychological and Personality Science, 3(6), 767-773.