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When Evidence Backfires
Don't read this blog post. Definitely don't read it to the end. Didn't I tell you not to read this blog post? You're still doing it... We can laugh at our inherent ability to be contrary, but unfortunately something similar can happen when we give a human being scientific evidence that debunks misinformation. One of the most depressing paradoxes of science communication is that not only can misinformation often spread faster and wider than the truth (just take the ubersuccessful but often not so factual "uberfacts" or the success of the paragons of science misinformation Natural News if you need examples); but even worse, combating misinformation with evidence can often have the complete and utter opposite of the desired effect. 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:
4. CDC Images of children with measles, mumps and rubella:
Image Credit: U.S. Centers for Disease Control and Prevention
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 worse off 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!
In an another study a similar backfire effect was found in Conservative voters who believe that Iraq possessed weapons of mass destruction. After receiving a correction that Iraq did not have weapons of mass destruction they became more likely to believe that Iraq had weapons of mass destruction than controls. The very same thing happened when Conservatives were presented with evidence that Bush's tax cuts failed to stimulate economic growth - in this case the percentage agreeing with the statement that Bush's tax cuts increased government revenue leapt from 36% to 67%, while the same evidence moved the views of non-conservatives in the other direction (from 31% to 28%).
Worryingly, the backfire effect has been shown to be particularly profound in older people who it is believed may remember a statement but forget the contextual information that the statement is untrue. Worse still, repeating that a claim is false can actually leave an even stronger impression that the claim is true. In one study, "the more often older adults were told that a claim was false, the more likely they were to remember it erroneously after a 3 day delay. The size of this effect is far from negligible. After 3 days, older adults misremembered 28% of false statements as true when they were told once that the statement was false but 40% when told three times that the statement was false". Interestingly, in this study the effect was the precise opposite in younger people - reinforcing that the claim was false made them less likely to believe the claim.
While younger adults became less likely to misremember a false claim as true after being told three times that it was false, older adults became more likely to misremember the claim as true. (Skurnik et al, 2005)
It seems that unless we are extremely careful, by trying to convince the most hardened cynics of the evidence we may end up doing more harm than good. The dire and seemingly growing need to combat misinformation on the MMR issue is one I've discussed at length on this blog. The intuitive and somewhat cliché response is often that we need to combat misinformation with better education. It seems however that at present some views are so entrenched that education alone just isn't cutting it. One study of views about global warming found that education doesn't seem to be as important a factor as political beliefs in determining agreement or disagreement with scientific consensus. The study concluded that "cultural worldviews explain more variance than science literacy and numeracy". In those with a "hierarchical individualist" worldview, scientific literacy was actually correlated with decreased beliefs in climate change, while scientific literacy was correlated with an increased belief in climate change amongst those with an "egalitarian communitarian" worldview.
The perniciousness of this problem can't be underestimated and we will without a doubt see much research in the field of tackling misinformation over coming years. It's an area I myself have become particularly interested in and I would genuinely like to hear your ideas. Hopefully if we can understand how we've gone wrong in the past we can have a better idea of how to stop ourselves going wrong again in the future. For now, the best simple resource that I have come across for understanding how best to handle misinformation is the Debunking Handbook (PDF) by John Cook and Stephan Lewandowsky, it's a five minute rollercoaster that (if you're anything like me) will leave you thinking long and hard.
Kahan D.M., Peters E., Wittlin M., Slovic P., Ouellette L.L., Braman D. & Mandel G. (2012). The polarizing impact of science literacy and numeracy on perceived climate change risks, Nature Climate Change, 2 (10) 732-735. DOI: 10.1038/nclimate1547
Nyhan B., Reifler J., Richey S. & Freed G.L. (2014). Effective Messages in Vaccine Promotion: A Randomized Trial., Pediatrics, PMID: 24590751
Nyhan B. & Reifler J. (2010). When Corrections Fail: The Persistence of Political Misperceptions, Political Behavior, 32 (2) 303-330. DOI: 10.1007/s11109-010-9112-2
Skurnik I., Yoon C., Park D. & Schwarz N. (2005). How Warnings about False Claims Become Recommendations, Journal of Consumer Research, 31 (4) 713-724. DOI: 10.1086/426605
Schwarz N., Sanna L.J., Skurnik I. & Yoon C. Metacognitive Experiences And The Intricacies Of Setting People Straight: Implications For Debiasing And Public Information Campaigns, Advances In Experimental Copyright 2007, Elsevier Inc. Social Psychology, 39 127-161. DOI: 10.1016/S0065-2601(06)39003-X
Why mega-eruptions like the ones that covered North America in ash are the least of your worries.
- The supervolcano under Yellowstone produced three massive eruptions over the past few million years.
- Each eruption covered much of what is now the western United States in an ash layer several feet deep.
- The last eruption was 640,000 years ago, but that doesn't mean the next eruption is overdue.
The end of the world as we know it
Panoramic view of Yellowstone National Park
Image: Heinrich Berann for the National Park Service – public domain
Of the many freak ways to shuffle off this mortal coil – lightning strikes, shark bites, falling pianos – here's one you can safely scratch off your worry list: an outbreak of the Yellowstone supervolcano.
As the map below shows, previous eruptions at Yellowstone were so massive that the ash fall covered most of what is now the western United States. A similar event today would not only claim countless lives directly, but also create enough subsidiary disruption to kill off global civilisation as we know it. A relatively recent eruption of the Toba supervolcano in Indonesia may have come close to killing off the human species (see further below).
However, just because a scenario is grim does not mean that it is likely (insert topical political joke here). In this case, the doom mongers claiming an eruption is 'overdue' are wrong. Yellowstone is not a library book or an oil change. Just because the previous mega-eruption happened long ago doesn't mean the next one is imminent.
Ash beds of North America
Ash beds deposited by major volcanic eruptions in North America.
Image: USGS – public domain
This map shows the location of the Yellowstone plateau and the ash beds deposited by its three most recent major outbreaks, plus two other eruptions – one similarly massive, the other the most recent one in North America.
The Huckleberry Ridge eruption occurred 2.1 million years ago. It ejected 2,450 km3 (588 cubic miles) of material, making it the largest known eruption in Yellowstone's history and in fact the largest eruption in North America in the past few million years.
This is the oldest of the three most recent caldera-forming eruptions of the Yellowstone hotspot. It created the Island Park Caldera, which lies partially in Yellowstone National Park, Wyoming and westward into Idaho. Ash from this eruption covered an area from southern California to North Dakota, and southern Idaho to northern Texas.
About 1.3 million years ago, the Mesa Falls eruption ejected 280 km3 (67 cubic miles) of material and created the Henry's Fork Caldera, located in Idaho, west of Yellowstone.
It was the smallest of the three major Yellowstone eruptions, both in terms of material ejected and area covered: 'only' most of present-day Wyoming, Colorado, Kansas and Nebraska, and about half of South Dakota.
The Lava Creek eruption was the most recent major eruption of Yellowstone: about 640,000 years ago. It was the second-largest eruption in North America in the past few million years, creating the Yellowstone Caldera.
It ejected only about 1,000 km3 (240 cubic miles) of material, i.e. less than half of the Huckleberry Ridge eruption. However, its debris is spread out over a significantly wider area: basically, Huckleberry Ridge plus larger slices of both Canada and Mexico, plus most of Texas, Louisiana, Arkansas, and Missouri.
This eruption occurred about 760,000 years ago. It was centered on southern California, where it created the Long Valley Caldera, and spewed out 580 km3 (139 cubic miles) of material. This makes it North America's third-largest eruption of the past few million years.
The material ejected by this eruption is known as the Bishop ash bed, and covers the central and western parts of the Lava Creek ash bed.
Mount St Helens
The eruption of Mount St Helens in 1980 was the deadliest and most destructive volcanic event in U.S. history: it created a mile-wide crater, killed 57 people and created economic damage in the neighborhood of $1 billion.
Yet by Yellowstone standards, it was tiny: Mount St Helens only ejected 0.25 km3 (0.06 cubic miles) of material, most of the ash settling in a relatively narrow band across Washington State and Idaho. By comparison, the Lava Creek eruption left a large swathe of North America in up to two metres of debris.
The difference between quakes and faults
The volume of dense rock equivalent (DRE) ejected by the Huckleberry Ridge event dwarfs all other North American eruptions. It is itself overshadowed by the DRE ejected at the most recent eruption at Toba (present-day Indonesia). This was one of the largest known eruptions ever and a relatively recent one: only 75,000 years ago. It is thought to have caused a global volcanic winter which lasted up to a decade and may be responsible for the bottleneck in human evolution: around that time, the total human population suddenly and drastically plummeted to between 1,000 and 10,000 breeding pairs.
Image: USGS – public domain
So, what are the chances of something that massive happening anytime soon? The aforementioned mongers of doom often claim that major eruptions occur at intervals of 600,000 years and point out that the last one was 640,000 years ago. Except that (a) the first interval was about 200,000 years longer, (b) two intervals is not a lot to base a prediction on, and (c) those intervals don't really mean anything anyway. Not in the case of volcanic eruptions, at least.
Earthquakes can be 'overdue' because the stress on fault lines is built up consistently over long periods, which means quakes can be predicted with a relative degree of accuracy. But this is not how volcanoes behave. They do not accumulate magma at constant rates. And the subterranean pressure that causes the magma to erupt does not follow a schedule.
What's more, previous super-eruptions do not necessarily imply future ones. Scientists are not convinced that there ever will be another big eruption at Yellowstone. Smaller eruptions, however, are much likelier. Since the Lava Creek eruption, there have been about 30 smaller outbreaks at Yellowstone, the last lava flow being about 70,000 years ago.
As for the immediate future (give or take a century): the magma chamber beneath Yellowstone is only 5 percent to 15 percent molten. Most scientists agree that is as un-alarming as it sounds. And that its statistically more relevant to worry about death by lightning, shark, or piano.
Strange Maps #1041
Got a strange map? Let me know at email@example.com.
Measuring a person's movements and poses, smart clothes could be used for athletic training, rehabilitation, or health-monitoring.
In recent years there have been exciting breakthroughs in wearable technologies, like smartwatches that can monitor your breathing and blood oxygen levels.
But what about a wearable that can detect how you move as you do a physical activity or play a sport, and could potentially even offer feedback on how to improve your technique?
And, as a major bonus, what if the wearable were something you'd actually already be wearing, like a shirt of a pair of socks?
That's the idea behind a new set of MIT-designed clothing that use special fibers to sense a person's movement via touch. Among other things, the researchers showed that their clothes can actually determine things like if someone is sitting, walking, or doing particular poses.
The group from MIT's Computer Science and Artificial Intelligence Lab (CSAIL) says that their clothes could be used for athletic training and rehabilitation. With patients' permission, they could even help passively monitor the health of residents in assisted-care facilities and determine if, for example, someone has fallen or is unconscious.
The researchers have developed a range of prototypes, from socks and gloves to a full vest. The team's "tactile electronics" use a mix of more typical textile fibers alongside a small amount of custom-made functional fibers that sense pressure from the person wearing the garment.
According to CSAIL graduate student Yiyue Luo, a key advantage of the team's design is that, unlike many existing wearable electronics, theirs can be incorporated into traditional large-scale clothing production. The machine-knitted tactile textiles are soft, stretchable, breathable, and can take a wide range of forms.
"Traditionally it's been hard to develop a mass-production wearable that provides high-accuracy data across a large number of sensors," says Luo, lead author on a new paper about the project that is appearing in this month's edition of Nature Electronics. "When you manufacture lots of sensor arrays, some of them will not work and some of them will work worse than others, so we developed a self-correcting mechanism that uses a self-supervised machine learning algorithm to recognize and adjust when certain sensors in the design are off-base."
The team's clothes have a range of capabilities. Their socks predict motion by looking at how different sequences of tactile footprints correlate to different poses as the user transitions from one pose to another. The full-sized vest can also detect the wearers' pose, activity, and the texture of the contacted surfaces.
The authors imagine a coach using the sensor to analyze people's postures and give suggestions on improvement. It could also be used by an experienced athlete to record their posture so that beginners can learn from them. In the long term, they even imagine that robots could be trained to learn how to do different activities using data from the wearables.
"Imagine robots that are no longer tactilely blind, and that have 'skins' that can provide tactile sensing just like we have as humans," says corresponding author Wan Shou, a postdoc at CSAIL. "Clothing with high-resolution tactile sensing opens up a lot of exciting new application areas for researchers to explore in the years to come."
The paper was co-written by MIT professors Antonio Torralba, Wojciech Matusik, and Tomás Palacios, alongside PhD students Yunzhu Li, Pratyusha Sharma, and Beichen Li; postdoc Kui Wu; and research engineer Michael Foshey.
The work was partially funded by Toyota Research Institute.
How imagining the worst case scenario can help calm anxiety.
- Stoicism is the philosophy that nothing about the world is good or bad in itself, and that we have control over both our judgments and our reactions to things.
- It is hardest to control our reactions to the things that come unexpectedly.
- By meditating every day on the "worst case scenario," we can take the sting out of the worst that life can throw our way.
Are you a worrier? Do you imagine nightmare scenarios and then get worked up and anxious about them? Does your mind get caught in a horrible spiral of catastrophizing over even the smallest of things? Worrying, particularly imagining the worst case scenario, seems to be a natural part of being human and comes easily to a lot of us. It's awful, perhaps even dangerous, when we do it.
But, there might just be an ancient wisdom that can help. It involves reframing this attitude for the better, and it comes from Stoicism. It's called "premeditation," and it could be the most useful trick we can learn.
Broadly speaking, Stoicism is the philosophy of choosing your judgments. Stoics believe that there is nothing about the universe that can be called good or bad, valuable or valueless, in itself. It's we who add these values to things. As Shakespeare's Hamlet says, "There is nothing either good or bad, but thinking makes it so." Our minds color the things we encounter as being "good" or "bad," and given that we control our minds, we therefore have control over all of our negative feelings.
Put another way, Stoicism maintains that there's a gap between our experience of an event and our judgment of it. For instance, if someone calls you a smelly goat, you have an opportunity, however small and hard it might be, to pause and ask yourself, "How will I judge this?" What's more, you can even ask, "How will I respond?" We have power over which thoughts we entertain and the final say on our actions. Today, Stoicism has influenced and finds modern expression in the hugely effective "cognitive behavioral therapy."
Helping you practice StoicismCredit: Robyn Beck via Getty Images
One of the principal fathers of ancient Stoicism was the Roman statesmen, Seneca, who argued that the unexpected and unforeseen blows of life are the hardest to take control over. The shock of a misfortune can strip away the power we have to choose our reaction. For instance, being burglarized feels so horrible because we had felt so safe at home. A stomach ache, out of the blue, is harder than a stitch thirty minutes into a run. A sudden bang makes us jump, but a firework makes us smile. Fell swoops hurt more than known hardships.
What could possibly go wrong?
So, how can we resolve this? Seneca suggests a Stoic technique called "premeditatio malorum" or "premeditation." At the start of every day, we ought to take time to indulge our anxious and catastrophizing mind. We should "rehearse in the mind: exile, torture, war, shipwreck." We should meditate on the worst things that could happen: your partner will leave you, your boss will fire you, your house will burn down. Maybe, even, you'll die.
This might sound depressing, but the important thing is that we do not stop there.
Stoicism has influenced and finds modern expression in the hugely effective "cognitive behavioral therapy."
The Stoic also rehearses how they will react to these things as they come up. For instance, another Stoic (and Roman Emperor) Marcus Aurelius asks us to imagine all the mean, rude, selfish, and boorish people we'll come across today. Then, in our heads, we script how we'll respond when we meet them. We can shrug off their meanness, smile at their rudeness, and refuse to be "implicated in what is degrading." Thus prepared, we take control again of our reactions and behavior.
The Stoics cast themselves into the darkest and most desperate of conditions but then realize that they can and will endure. With premeditation, the Stoic is prepared and has the mental vigor necessary to take the blow on the chin and say, "Yep, l can deal with this."
Catastrophizing as a method of mental inoculation
Seneca wrote: "In times of peace, the soldier carries out maneuvers." This is also true of premeditation, which acts as the war room or training ground. The agonizing cut of the unexpected is blunted by preparedness. We can prepare the mind for whatever trials may come, in just the same way we can prepare the body for some endurance activity. The world can throw nothing as bad as that which our minds have already imagined.
Stoicism teaches us to embrace our worrying mind but to embrace it as a kind of inoculation. With a frown over breakfast, try to spend five minutes of your day deliberately catastrophizing. Get your anti-anxiety battle plan ready and then face the world.
A study on charity finds that reminding people how nice it feels to give yields better results than appealing to altruism.