The Backfire Effect and Human Nature

Big Thing has an essay about the backfire effect, the name given to a well-established psychological phenomenon whereby people actually become more entrenched in a false belief when confronted with evidence that shows that belief to be incorrect.

This horrifying phenomenon known as the backfire effect was demonstrated once again recently by a study of the responses of parents to various different forms of evidence that vaccines are not dangerous. The randomized controlled trial drew from four CDC sources, all designed to use scientific evidence to demonstrate why children must be vaccinated…

In all four cases, none of the materials increased parents intentions to vaccinate their children. The effects of the straight forward information about measles, mumps and rubella were fairly neutral. The images of children with measles, mumps and rubella and the mother’s narrative about her hospitalized child both had the unintended effect of increasing beliefs in vaccine side effects. The images also somehow increased false beliefs that vaccines cause autism. The material that refuted the MMR-autism link successfully reduced false beliefs about the idea that vaccines cause autism but astoundingly actually reduced the intent to vaccinate in parents with the most anti-vaccine beliefs.

This isn’t the first time we’ve seen depressing findings from studies attempting to refute vaccine myths. A study described in a paper by Schwarz et al, found that a CDC flyer containing “facts and myths” about vaccines increased intentions to vaccinate immediately but had the opposite effect after only half an hour – when the participants began remembering the myths as facts. It seems we really are glorified goldfish when it comes to remembering the separation between fact and fiction. When the experimenters created a version of the flyer where myths were rephrased as facts the flyer successfully increased intention to vaccinate, this contrasted with the original CDC flyer which left participants off worse than when they started. Avoiding reference to myths is far from a perfect solution however, because it fails to directly address the myths that are in circulation.

As if things couldn’t get any more depressing, Norbert Schwarz the coauthor of the “facts and myths” paper suggests that when a respected institution such as the CDC weighs in and debunks a claim, this can actually end up lending credence to the claim in people’s minds. Schwarz cites as an example an internet rumor about flesh-eating bananas that was so prolific it was debunked by the CDC website. When this happened, the flesh-eating banana scare grew and began actually being attributed to the CDC!

What does this say about human cognition and our ability to use reason? Nothing good, I imagine, though I’m hardly learned enough in the psychological literature to address this particular phenomenon. I wonder if Dr. X and others with some training in psychology and cognitive neuroscience might weigh in on it?

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  • Doubting Thomas

    Explains why all my brilliant reasoning and logic and information fails to convince.

  • theschwa

    Speaking of backfires, have you seen the epic fail #myNYPD??

  • David C Brayton

    One thing I’ve always found frustrating is that I went to school for 21 (!) years and was praised for my accomplishments. Yet, rationality is not a highly valued trait in the real world. People will perform much better in the real world if they are funny and good looking instead of rational and logical


  • John Pieret

    What does this say about human cognition and our ability to use reason?

    Most likely that we have never been a “rational” species. We use reason only at the periphery … where it doesn’t affect our cherished beliefs … and that goes for all groups, theists, atheists, secularists and everything in between.

  • Jacob Schmidt

    The material that refuted the MMR-autism link successfully reduced false beliefs about the idea that vaccines cause autism but astoundingly actually reduced the intent to vaccinate in parents with the most anti-vaccine beliefs.

    I wonder if this effect is only short term.

  • richardelguru

    I’ve often thought that calling our species Homo sapiens or in extreme cases Homo sapiens sapiens has definite shades of “the lady doth protest too much, methinks” about it.

    (As a probably unwise aside: did you know that the ‘doth’ version of that quote is only in the second Quarto of Hamlet, the First Quarto and the otherwise authoritative First Folio are rather more modern and leave out the ‘doth’ but “the lady protests too much” ain’t Shakespearian enough for us, so, in a sort of ‘play-it-again-Sammy’ move, we go with the better quote rather than what might well be the real one. Perhaps we do that unwisely if not particularly well.

    And I really must stop doing all these silly asides, however Shakespearian they may be.)

  • marcus

    Ed “What does this say about human cognition and our ability to use reason?”

    It says we are fucking doomed.

    Oh well, maybe the next sentient species to step up will actually be rational..

  • cry4turtles

    Perhaps we can sum it up with a single-sentence philosophy that has stood the test of time: Common sense is not so common.

  • Pierce R. Butler

    … reduced the intent to vaccinate in parents with the most anti-vaccine beliefs.

    Wouldn’t that set of parents have had the closest-to-zero intent to vaccinate to begin with?

  • eric

    The material that refuted the MMR-autism link successfully reduced false beliefs about the idea that vaccines cause autism but astoundingly actually reduced the intent to vaccinate in parents with the most anti-vaccine beliefs.

    My bold. This does not particularly bother me. As with the fight aganist creationism, the point of sound science outreach and communication is not – and has never been – to change the minds of the die hard nuts on the fringe. Its to change the minds of the somewhat misinformed but generally open-minded middle of the road folks.

  • ragarth


    I wonder if this phenomenon is cross cultural, or if it’s modulated in certain cultures.

    To the SCIENCE cave, Robin!

  • John Pieret


    Keep up the asides. silly or not … even if the the lady doth protest too much! The funny thing about knowledge is that it often sneaks up on you when you are least expecting it.

  • comfychair

    Only a witch would say there’s no such thing as witches!!!1

  • richardelguru

    Thank you John, though I find that it has an unfortunate tendency (at least with me) to gallop, or thunder up rather than sneak.

  • thomaspenn

    I’ve always loved this quote on the purpose of reason.

    Balloon Juice

    Human rationality did not evolve in order to solve differential equations. That’s an epiphenomenon of little consequence. Human rationality evolved in order to invent ingenious ways of justifying crazy primate behavior to the rest of the tribe of murderous primates.

  • Modusoperandi

    Well, sure, but it doesn’t effect me. And the more you prove it does the more it doesn’t.

  • Chiroptera

    What does this say about human cognition and our ability to use reason?

    That’s a good question. Because despite the results of these studies, science has advanced pretty far; rather than stubbornly hold onto beliefs about the earth being flat, the sky being a solid dome, the stars going around the earth, life being maintained by a unique “vital force,” people allowed the evidence to change our beliefs about very fundamental ideas in the natural and social sciences.

    And as far as social justice is concerned, despite the slow pace of change and some of the retrograde movement recently, I think most people would agree that the modern US is a much better place than medievel Europe or even turn of the 19th century North America.

    I have no idea what these studies mean, since it is undoubtably true that people in real life do learn and change their beliefs about fundamental things.

  • Dr X

    I have A LOT to say about this subject, but my time s limited today, so I’m going to lift a chunk from a post I wrote back in 2008, speculating on why it is that partisan information processing shifts from rational to emotional when partisans are confronted with negative information about a candidate they support.

    Social psychologist Drew Westen conducted some research showing that political partisans don’t allow new negative information about a candidate to weigh against the candidate favored by the partisan. He found evidence that this is the case behaviorally and neurologically. The backfire effect (Brendan Nyhan’s work) may simply be an extension of that phenomenon, generalized to the level of tribe and tribal beliefs. The interesting question is: why are we set up to operate this way? Doesn’t the collapse of rationality adversely affect our ability to survive and thrive?

    If you think about Westen’s or Nyan’s findings as manifestations of neurological kludges, evolved, beneficial, neurological shortcuts/heuristics, you can see how emotions superseding reason might, on balance, actually be beneficial to survival and propagation of a genetic line.

    Why do political partisans go brain-blind to unsettling facts about their favorite politicians?

    Perhaps it has something to do with attachment and idealization. An idealizing capacity is intertwined with the ability to form our most intense, beneficial attachments and social alliances. Partial suspension of realism and rationality is required to forge and maintain these attachments. We must, to an extent, abandon full objectivity and ignore things that would undermine the formation of these vital relationships. After all, why should parents love their own babies so much more than all other babies? Why should babies and children feel so much more attached to their own parents? And why, indeed, should we fall in love with people who are not necessarily objectively better people than the rest of humanity?

    If the mechanisms that help us to form and maintain beneficial social attachments are in play when we form political loyalties, then it may be that we also have to go a little bit blind to fall for a political candidate.

    I’d add to what I wrote previously that we do something similar when we form tribal alliances and identifications. Why become emotionally attached to a tribe, a party, a community or a nation? Communities protect themselves from competing communities, so community loyalty is beneficial to survival. Anything that might undermine that loyalty could potentially undermine the survival of the community. An attack on my fellow tribesman or an attack on the beliefs that bind us together is an attack on me.

    Imagine in a war how appraisals that undermine loyalty to the person fighting beside you might adversely effect the survival of your group as a whole, and by extension the proliferation of the genetic lines in your clan. And in the situation opposite war, imagine how mutually beneficial cooperation might be undermined if rational appraisals of those with whom we form beneficial bonds, constantly undermine those bonds to the point that we couldn’t maintain important, beneficial social bonds.

    So consider the backfire effect in this light: When my candidate is attacked or when you challenge my belief, even quite rationally, you’re attacking me, threatening my survival. I don’t care so much about the bases for the attack. Instead, my more primitive defenses are mobilized (think fight or flight).

    All of this begs the question, how do you persuade people to change political alliances or beliefs associated with those alliances? Well, you don’t do it with reason. You have to make a connection at the emotional level, getting people to reformulate allegiances based on an understanding of allegiances as emotional phenomena.

    This can be very hard for hyperrational people (stereotypic non-emotional brainiacs) to grasp or accept because they may not have the phenomenological bases for appreciating the power of group bonds. A further question is why is there is so much variation in the distribution of this characteristic within populations? We have emotionally detached brainiacs on one end of the spectrum, and creatures of complete emotional loyalty on the other end of the spectrum.

    You don’t have think too hard to come up with reasons why variation within a large group could be beneficial to the group as a whole. Notice how there is a certain type of brainiac that has a great deal of trouble maintaining strong social bonds because they have to argue with everything they deem irrational or wrong. It could be difficult for that type of individual to maintain loyalties that protect the group. On the other hand, these same characters often make great contributions to the group through cold analyses. Sometimes people with great insights are the worst salespeople for those insights, but their insights are adopted by the group over the course of time, often because better salespeople adopted and promulgated their insights more effectively.

    Please excuse any ineloquence, spelling/grammar problems above. I wrote much more than I’d expected to write and I had to bang it out and post more quickly than I’d have liked if I had more time.

  • D. C. Sessions

    Rushed and “ineloquent” as may be, thank you Dr. X.

  • Dr X


    You’re welcome.

  • Michael Heath

    Dr. X. writes:

    All of this begs the question, how do you persuade people to change political alliances or beliefs associated with those alliances? Well, you don’t do it with reason. You have to make a connection at the emotional level, getting people to reformulate allegiances based on an understanding of allegiances as emotional phenomena.

    Republicans love to argue we have a moral obligation to reduce the deficit* in order that future generations won’t have to suffer from a punitive share of their tax revenues paying the interest on debt accumulated during our times. So why not use that same emotion-based argument regarding the threat climate scientists report on global warming?

    I have seen it used but not much. One reason why I don’t think it will work is because it doesn’t work on the deficits. That GOP talking point is just that, rhetoric. I observe no authentic Republican concern about future generations suffering from deficits generated now that adds to the long-term federal debt; instead Republicans are merely seeking to win an argument.

    So if we’re going to use emotion-based arguments to convince people who are in denial, we need to find arguments that actually work; where we can’t necessarily depend on emotion-based these same denialists use amongst each other.

    Perhaps the best emotion-based and rational “argument” I’ve seen that’s changed people’s minds is gay people coming out of the closet. That had led to increasing support to eradicate discrimination against gay people. I’m not sure who we use this benchmarking result to change “hearts” and minds on supporting policies that will mitigate the AGW threat.

    *As those who are economically literate know, Republicans don’t demonstrate any actual concern about the deficit, especially as it relates to GDP. Their proposed economic policies, both argued and implemented, not only increase the debt, but also guarantee that debt is a larger share of GDP.

  • Dr X


    My comment on how opinions might change was necessarily brief. I’d in no way suggest that you simply hit people at an emotional level and their opinions change. Rather, if you wish to move people at the margins, you have to understand allegiances as more complex networks of emotional phenomena, with everything that entails. Moving emotionally-driven group identifications is not a one shot deal and it can’t be parsed into changing opinions on individual subjects in isolation from the a network of beliefs associated with group identity. The deficit, states rights, attitudes on race, welfare, taxes and the like aren’t necessarily related in a logical sense, but they come as a binding package of group identity. It’s the emotionally-laden group identity that has to be eroded to open the specific beliefs to modification.

    In the examples you use of the deficit or climate change, the problem is that you don’t change these opinions in isolation, one at a time by emotional appeal. The broader emotional identifications have to change in a more wholesale way and that requires understanding the underlying reasons for the alliances that include the package of shared, binding beliefs.

    We do this in therapy and it’s a slow, difficult process full of pitfalls and wrong turns, but you don’t get there by rational persuasion or argument as your primary modality. Rational appeal can be tactically supplemental and useful in the right moments, but a strategy that recognizes broader, unconsciously-driven emotional identifications is essential.

    Think about a person who chronically feels like a victim. They have a victim identity. They view all challenges and problems from the victim perspective. The alteration of this pattern doesn’t come about by arguing over specific events and stories in which they see themselves as a victim. To the endless consternation of the people in their lives, arguing rationally with their victim take doesn’t bring about change. The alteration comes with a broader emotional erosion of the victim identity that frames their views of all events.

    IMO, in America politics, our most problematic challenge involves the powerful group identification of conservative, Southern white males and the package of immovable beliefs that binds them together. The problem is that this identify was forged in war, defeat and humiliation that is culturally embedded in a conservative Southern psyche. Its a group that has never gotten off its group warfare footing. Conservative strategists have been very good at capitalizing on this, emphasizing culture wars and an assortment of symbolic markers of group identity. Simple emotional appeals on policy by policy question don’t address the broader identification.

    I think that it’s exceedingly difficult to change this situation because of opportunities lost long ago. The South as a whole was never forced to confront the truth about the South and the war. There were no public reconciliation convenings, no Nuremberg trials, no genuine reckoning with the facts that would break the binding group allegiance that undergirds an us versus them paradigm. I think changing this situation, at this late stage in the game might not even be possible, but if we’re to succeed, we’ve got to reckon with the emotional dimensions of conservative, Southern white group identification.

  • Michael Heath

    Dr. X writes:

    I’d in no way suggest that you simply hit people at an emotional level and their opinions change.

    I never meant to insinuate you did. I was merely riffing off your post to point out that even if we used emotion-based arguments equivalent to those used by our political opponent, that’s still not necessarily sufficient to change those same “hearts” and minds. Thanks for then explaining the mechanics on why this is.

    I’ve long seen a strong behavioral relationship between southern white conservatives and Protestant German-Americans who immigrated here around or after WWII. Your description of the southern experience goes well with the German-Americans, except German-Americans avoided the Nuremberg trials’ findings or instead project that behavior only onto Nazis where they identify only as Germans – as if the two groups were distinct. Avoiding German complicity for WWII is very strong amongst this group, whereas the Germans who stayed seemed to have predominately confronted and since adapted to a far better place.

    Interestingly, an American civil war historian who became FDR’s ambassador to Germany in the early-1930s studied in Germany earlier that same century. William Dodd found very similar attitudes between southern Americans in the late-1900s who were bitter about the Civl War and Germany’s culture in the 1930s. He was able to take what he knew about southern white racists and come to conclusions about the threat of Nazism far quicker than most powerful Americans, though FDR was at the forefront of quickly recognizing this threat, which is exactly why he picked Dodd to be his ambassador when the Nazis first became politically dominant. Cite: (Erik Larson’s In the Garden of Beasts: Love, Terror, and an American Family in Hitler’s Berlin; link is to my review of the cite.)