About the SA Blog Network

Guest Blog

Guest Blog

Commentary invited by editors of Scientific American
Guest Blog HomeAboutContact

The perception gap: An explanation for why people maintain irrational fears

The views expressed are those of the author and are not necessarily those of Scientific American.

Email   PrintPrint

A number of wonderful books decry the public’s seemingly irrational perceptions of risk. Seth Mnookin’s The Panic Virus is the latest, and builds on Michael Specter’s Denialism and Chris Mooney’s Unscientific America. Strong as each book is, unfortunately none get to the heart of the matter, and describes not how we feel, but WHY. Why are some people too afraid of vaccines, or fluoride, or radiation from cell phones, or all the other modern bogeymen that science says aren’t all that dangerous? And why aren’t we more afraid of climate change or obesity or antibiotic resistant bacteria, or other perils that science has identified as huge imminent threats?

These books wisely observe the dangers that result when we are more afraid than the evidence warrants, or not afraid enough when the evidence screams "Beware." But to mitigate those dangers and close that Gap, we need to do more than just observe and lament that our fears don’t match the facts. We need to understand why we make these mistakes, and why these misperceptions arise. We need to understand the roots of risk perception if we want to figure out how to reduce the risk of what I call (in How Risky Is it, Really? Why Our Fears Don’t Always Match the Facts) The Perception Gap.

Each author takes a shot at this, but falls short. They rightly heap blame on the media, and poor risk communication by government and the scientific community, and there is even a bit of recognition of cognitive biases. Accurate as all that is, the body of evidence that helps explain the psychology of risk perception is far richer, and offers much more detailed explanations for why our fears so often don’t seem to match the facts. Here is just some of the research relative to the fear of vaccines.

Most importantly, risk perception is not, and can never be, purely rational. Risk can be measured and studied and factually described, but no matter what those facts say, our perception of those facts is intrinsically subjective. We subconsciously apply psychological and instinctive filters that help us quickly determine if that information might suggest danger, well before we have all the facts, forming the critical first judgment about how to stay safe, against which we interpret everything that follows. That helps explain why it doesn’t matter if Wakefield is debunked. It’s very hard to unwire the neural connections that represent our first assessment of how to protect ourselves. This system is rooted in the architecture and chemistry of the brain’s ‘fear’ systems. We are hard wired to respond to risk with a mix of facts and feelings.

And then there is four decades of research from psychology, which has revealed a common set of affective/emotional characteristics that make some risks feel scarier than others, the facts notwithstanding. Several help explain why some people are excessively afraid of vaccines;

* Uncertainty. When we are uncertain, as are parents with autistic kids, we grab on to anything that answers our questions, because that sense of knowing affords us a reassuring feeling of control. Control is vital to anyone who is afraid, worried, uncertain.

* Trust. When authority dismisses our fears, our trust in authority goes down and our resistance to it goes up. The parents of autistic kids were dissed by the establishment. By the governments that were supposed to keep them and their kids safe. By doctors. By science. The parents were called irrational, emotional, ignorant. That badly damaged trust, and when trust goes down, resistance to factual information from untrusted goes up.

* Choice. A risk imposed on us feels scarier than when we choose to take it ourselves. To many opponents vaccination feels involuntary though there are opt outs. As Barbara Loe Fisher, opponent of vaccination, said "The battle we are waging will determine what both health and freedom will look like in America." Freedom? Vaccines as a Tea Party issue? Yes, because of the psychological importance of choice.

* Human-made or Natural. Vaccines are human-made (though of course they are just manufactured versions of natural substances), and human-made risks scare us more than natural ones. A mother in a recent documentary on vaccination said she is less afraid of measles for her child "…because it’s natural."

* Risks versus Benefits. Fear of vaccines goes up as fear of the diseases they have all but eliminated (ergo the benefit of the vaccines) goes down. But where vaccination rates are so low that measles and whooping cough are coming back, the fear of those diseases is rising and pushing back against those who opt out of vaccination. This is a great example of how the same risk can lead to different perceptions not based just on the facts, but how we feel about the risks and benefits, the tradeoffs.

This is way more than an alarmist media or poor risk communication by government or poor science education in schools. The real reason why our fears sometimes don’t match the facts, about vaccines or any risk, is the primal emotional/instinctive psychology that helps us survive. Given the power of that imperative it’s small wonder that our perceptions of risk, informed by these instincts, are so fiercely held, and so deeply resistant to reason.

As powerful as this psychology is, and as deeply a part of being human as it is, describing it as right or wrong, rational or irrational, ignores (or arrogantly denies) the inescapable reality of the complex imperfect affective way humans perceive and respond to danger. Calling people who do this dumb is dumb. Instead, we need to accept that we will always be at risk from The Perception Gap. It is just part of who we are. Rather than lament it and try and fight it in the naive pursuit of perfect rationality, we need to use what we’ve learned about risk perception to manage the risk of our misperceptions, with policies and regulations and incentives and communication and education campaigns, that help us deal with this danger just as we already do so many other physical threats. We have to go beyond just observing that we get risk wrong, and use our knowledge of why, if we want to do a better job of getting risk right.

Some interesting reading:

* On the neuroscience of fear, the Emotional Brain, Joseph LeDoux

* On the intrinsically affective nature of our perceptions, Descartes Error, Antonio D’Amasio

* For more of the “Fear Factors” that make some risks feel scarier than others, Chapter Three of How Risky Is It Really? available free at


About the Author: David Ropeik is an Instructor at the Harvard Extension School and author of "How Risky Is It, Really? Why Our Fears Don’t Always Match the Facts".

The views expressed are those of the author and are not necessarily those of Scientific American.

Tags: , ,

Comments 20 Comments

Add Comment
  1. 1. jimmywat 11:29 am 02/3/2011

    Another unscientific article that claims that all scientists are in agreement on any of the above claims. Many climate professionals do not agree that whatever is happening is man made or extraordinary. Many scientists do not believe in the Big Bang. Many have questioned vaccines, floride, etc. Yet, without proof or reference to studies on both sides, you assert that "science has proved" in some very disputed fields. This is not scientific, but propaganda. Provide the facts and experts from all sides, not just your prejudice!

    Link to this
  2. 2. lamorpa 11:33 am 02/3/2011

    We all know vaccines cause Aujennymccarthytism. That fear is definitely justified.

    Link to this
  3. 3. sbscienceny 1:05 pm 02/3/2011

    Please, Mr. Ropeik do some research before posting nonsense.
    Too much fluoride is dangerous. There is now data on showing that cell phone radiation can damage DNA.
    Your vaccine knowledge is equally wrong: "Vaccines are human-made (though of course they are just manufactured versions of natural substances)" – you mean mercury and aluminum too? And of course, we "naturally" get injected by a concoction of antigens and other chemicals too? What an Ignoramus! Scientific American editors, please wake up and stop allowing such nonsense! You are losing credibility.
    Vaccines are useful but the real debate should be about when and how many vaccines to give! Please stop allowing to give space to journalists who are not qualified to judge the scientific merit of this issue.

    Link to this
  4. 4. sbscienceny 1:12 pm 02/3/2011

    Oops. I meant stop giving space to journalists who are not qualified to judge the scientific merit of this issue.

    Link to this
  5. 5. sbscienceny 1:16 pm 02/3/2011

    and your point is? She was able to help her kid, more than we can say about the scientific establishment.

    Link to this
  6. 6. lamorpa 1:50 pm 02/3/2011

    You’re not serious right? JMcC’s anti-vaccine tirade did not ‘help her kid’ and could be implicated in (just one case) the death of 8 children of whooping cough in California last year. Or is no harm done there because they were not her kids?

    Your comment actually demonstrates precicely what the article was stating. You bring up the old flouride, cell phone radiation, etc. ‘issues’ without attaching any meaningful detriment/benefit and probability analysis at all (or even suggest that it could be relevant – e.g. bananas must be eliminated; people have slipped and died on their peels). The article’s author can thank you for providing a real-world example.

    Link to this
  7. 7. sbscienceny 2:58 pm 02/3/2011

    What are you talking about? The author is using the fluoride, cell phone example as if those are proven cases of hyped fear and that is not the case. Too much fluoride IS dangerous, that is a scientific fact. Some states now have stopped supplementing it in the water because people are getting it from their toothpaste. Cell phone radiation causes DNA damage, and DNA damage can cause cancer. Do cell phones cause cancer? I don’t know but I would sure like to see more research on it since the DNA damage research opens up a mechanistic possibility. I sure want kids to spend as little time on cell phones as possible. Some of the brain sergeants are doing the same but I am sure you think they are just misguided. Do mercury, aluminum cause neurological damage? YES, that is also a scientific fact. Are the epidemiological studies sufficient to argue that they cannot cause harm in vaccines? NO. In California the major problem is that the teenage population is not protected against whooping cough anymore. But it is always easier to blame those who do not vaccinate. Look I know it is all about cost benefit analysis. It is easier for the government to roll out ever increasing number of vaccines than to provide quality care for all kids. Countries with less vaccines have lower under five mortality rates. That is a fact too. You can attack JM as much as you want but it is a cheap shot, not science.

    Link to this
  8. 8. lamorpa 3:26 pm 02/3/2011

    Skip the details and just insert ‘Standard Conspiracy Theory Argument 1, 1a, 1b, etc.’ It will save typing. 1) Too much flouride with crush you if 2,000 pounds of it are dumped on you. What’s your point? 2) Cell phones causing DNA damage that leads to cancer is very, very far from ‘proven’ (studies are ongoing, but initial results indicate it is an insignificant and/or undetectable factor) 3) Why do you keep putting mercury in the same sentances as vaccines? Mercury has been removed from domestic vaccines for decades. Do you think if you keep saying it over and over again, mercury will materialize? 4) "…the teenage population is not protected against whooping cough anymore. But it is always easier to blame those who do not vaccinate." As opposed to who? How do you think people end up being vaccinated? (Hint: By being vaccinated) 5) "It is easier for the government to roll out ever increasing number of vaccines than to provide quality care for all kids." This may be literally and practically true, but I think you mean this in more of a conspiracy theory tone. 6) "Countries with less vaccines have lower under five mortality rates." (Just to help you out here) No. But if you believe this, I think a rational discussion is over at this point.

    Link to this
  9. 9. sbscienceny 3:43 pm 02/3/2011

    I am not going to respond to everything because people can see who is trying to have a rational discussion here and who is talking nonsense.
    Mercury is still in flu shots that children and pregnant women get regularly. I also mentioned aluminum because mercury is the only possible culprit here.
    Teenage kids in California, who got their DTP or DTaP shots as babies and toddlers are not protected anymore because the vaccine does not give lifelong immunity so they can just as easily spread whooping cough as unvaccinated kids.
    The US is 33 or 34 in child mortality rates after a lot of European countries that give less shots, on average 18 as opposed to the 36 in the US.

    Link to this
  10. 10. lamorpa 5:34 pm 02/3/2011

    The mercury exposure in a flu vaccine is approximately 1/4 the dose you get from eating a can of tuna. I know anti-vaccs don’t like to have that fact brought up, but it’s still true. I do like the switch from the subject, childhood vaccines, to flu vaccines, to keep the mercury issue going. Mercury, mercury, mercury.

    Are you actually suggesting children shouldn’t get whooping cough vaccine because it may not give lifelong immunity? Why give any kind medical treatment at all? People always die in the end. Right?

    People in European coutries drive smaller cars on average, and play a lot more soccer. Should I decide this is the reason for their lower child mortality rates?

    ‘Nonsence’ is making causal inferences from merely correlated events. That’s where science ends. What else can I say?

    Link to this
  11. 11. writer1508 6:14 pm 02/3/2011

    Lamorpa, you are absolutely correct and as far as sbscienceny is concerned i have no idea where you get your information from be it empirical,statistical or whatever? Outcome studies so far as the ones i’ve seen show no evidence whatsoever that cancer can result from the use of cell phones! Additionally, America has fallen way down the list of countries that provide much better health care in 3rd world industrialized countries. I wouldn’t want to be the son,daughter,mother or father w/my health care needs dependent on you & end up dying fr. a flu bug because you were more worried about the ramifications of long term side effects from mercury being in my flu shot!

    Link to this
  12. 12. Matthewt69 8:24 pm 02/3/2011

    The interesting thing is that not everyone fails to assess risk rationally. So how do you persuade the people who consistently get it wrong without compromising on the facts of the matter? You can use the law in the same way that the law is used to enforce safe driving behaviour, and sometimes you can just allow people to make their own choices (in the cases when that isnt going to pose a high risk to other people)

    Link to this
  13. 13. nyscof 9:49 am 02/4/2011

    Apparently, this writer failed to read a better article in Scientific American "Second Thoughts About Fluoride" by award-winning investigative scientific journalist, Dan Fagin

    “Some recent studies suggest that over-consumption of fluoride can raise the risks of disorders affecting teeth, bones, the brain and the thyroid gland,”
    reports Scientific American editors
    “Scientific attitudes toward fluoridation may be starting to
    shift,” writes author Dan Fagin who reveals:

    There is no universally accepted optimal level for daily intake of fluoride. Some researchers even wonder whether the 1 mg/L added into drinking water is too much

    After 3 years of scrutinizing hundreds of studies, a National Research Council (NRC) committee “concluded that fluoride can subtly alter endocrine function, especially in the thyroid – the gland that produces hormones regulating growth and metabolism."

    a series of epidemiological studies in China have associated high fluoride exposures with lower IQ.

    epidemiological studies and tests on lab animals suggest that high fluoride exposure increases the risk of bone fracture, especially in vulnerable populations such as the elderly and diabetics

    Fagin interviewed Steven Levy, director of the Iowa Fluoride Study which tracked about 700 Iowa children
    for sixteen years. Nine-year-old “Iowa children who lived in communities where the water was fluoridated were 50 percent more likely to have mild fluorosis…
    than [nine-year-old] children living in nonfluoridated areas of the state,” writes Fagin. Levy is studying fluoride’s effects on their bones.

    genetic,environmental and even cultural factors appear to leave some people much more susceptible to the effects of fluoride.

    “What the [NRC]committee found is that we’ve gone with the status quo regarding fluoride … for
    too long… and now we need to take a fresh look,” NRC Fluoride Panel Chairman Dr. Doull says, ” In the scientific community, people tend to think that its settled… But when we looked at the studies that have been done, we found that many of these questions are unsettled and we have much less information than we should, considering how long this [fluoridation] has been going on. I think that’s why fluoridation is still being challenged so many years after it began, In the face of ignorance, controversy is rampant.”

    Link to this
  14. 14. dropeik 11:39 am 02/4/2011

    Just read the responses to my essay. Thanks. For essentially bearing out the point, that risk perception is subjective. Lots of different opinions about the same basic data. Dan Fagin’s article included. Note what I wrote;
    "As powerful as this psychology is, and as deeply a part of being human as it is, describing it as right or wrong, rational or irrational, ignores (or arrogantly denies) the inescapable reality of the complex imperfect affective way humans perceive and respond to danger. Calling people who do this dumb is dumb."

    There is no blame here. Just the observation, based on a lot of evidence from neuroscience and elsewhere, that the arguments we all make about risk, while seemingly based on the facts, are actually interpretations of those facts, which are based on deeper affective drivers.

    Link to this
  15. 15. notslic 8:59 pm 02/4/2011

    David, How nice to see an author of an article respond to comments. Your theory here can be extrapolated to a multitude of other issues, including religion, politics and science in general. People have different views, which affect their perceptions. But isn’t that what makes us human? Few, if any, other creatures view a specific idea differently than their peers. This will be what makes us ultimately immortal, or doomed.

    Cheers!? Jeff

    Link to this
  16. 16. hgrey 7:03 pm 02/5/2011

    As a clinician who works with children who exhibit a range of phobias and anxiety-related problems, I often see the disconnect between perception and reality. Many times, incorrect, outdated or incomplete thoughts have become embedded in a person’s psyche and drive the fear and anxiety. Emotional content from a memory often acts as "cement" for such thoughts. However, the author chooses a controversial topic–the fear of vaccines and their possible connection to autism–which raises an entirely different issue. How does the country decide on public health policy if everyone–from parents to celebrities to politicians–thinks they are an expert on such a complex topic. It IS "dumb" to allow such lay people to shape the debate about public health policy, and thus infect others with their opinions. Just because a TV personality has a child with autism does not make them an expert on the possible causes of autism; it makes them an expert on raising a child with autism.

    Link to this
  17. 17. bucketofsquid 12:05 pm 02/10/2011

    jimmy – Provide some facts and experts, etc. If you want to criticise, fine, just do so in an intelligent way and not via vague rumor. Otherwise it is just a case of the pot calling the kettle a cooking utensil.

    Link to this
  18. 18. bucketofsquid 12:09 pm 02/10/2011

    Mr. (or Dr.) Ropeik has better credentials than some semi-anonymous dolt on the forums. Your information is more than a decade out of date. Aluminum and mercury have been gone from vaccines for quite some time. Their removal coincides with an increase in autism rates. Maybe if you were not irrationally frightened you could make an intelligent arguement. Maybe not.

    Link to this
  19. 19. bucketofsquid 12:12 pm 02/10/2011

    Was she? How many children died because of her ignorant ranting based on a non-scientific study done to pad one man’s pockets? A study that pointed to mercury which is no longer in vaccines and yet the illness the study claimed to find the cause of is more common than ever now that mercury isn’t involved.

    Link to this
  20. 20. bucketofsquid 12:29 pm 02/10/2011

    I have an irrational fear of spiders because as a child a batch of spider eggs hatched in my room. They were a beautiful metallic green with bright red legs. I ended up with over 30 spider bites. Other than a bit of itchyness and pain, no harm was done. I will always hate and fear spiders.

    This does not mean I hunt and kill spiders or believe they are evil. Spiders in my house or car get relocated to the yard. Spiders in the yard get avoided. We don’t have to let our fears own us as their slaves.

    nyscof – I have followed the studies on cell phones, mercury and flouride with great interest. There is some evidence that there are risks involved with each. These risks have not been clearly identified so I reserve judgement until they are. I don’t use a flouride toothpaste. I don’t drink mercury any more (kids do dumb stuff). I minimize use of cell phones because I don’t like phones in general. Oddly enough, I’m not a paragon of health.

    Link to this

Add a Comment
You must sign in or register as a member to submit a comment.

More from Scientific American

Email this Article