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Does evidence change our views? Why Not? What can we do about it?

This is a 2-part series on what changes our views. Part 1 looks at why evidence is not effective in changing our views, and why is this is the case. Part 2 examines what we can do to change the minds of others (and ourselves) if evidence is ineffective.

When we see someone holding a view that is, to us, obviously wrong, our first response is typically to provide information and evidence that counteracts their view. But recall through your own experiences: does this really work? If it did, why are there people who still believe in horoscopes, that seeing a black cat is bad luck, in a flat-earth, in young-earth creationism, or that there is no man-made climate change? All of these are objectively wrong, with extensive evidence that can be easily found. Is evidence really useful to change people's minds?

Does evidence and expert opinion change your view? 
Cass R. Sunstein, S. Bobadilla-Suarez, S. Lazzaro, and Tali Sharot,

“How People Update Beliefs About Climate Change: Good News and Bad News,”

The experiment:

  • Climate Change Believers and Deniers were divided into 2 groups:


Each group was given different evidence

  • Group A was told that after recent evidence, scientists and experts have assessed that climate change is much more serious than previously thought​
  • Group B was told the opposite, that recent evidence shows climate change is much less serious than previously thought

  • What do you think the reactions were?


The results:​

  • People accepted the evidence only if it fits their original worldview

    • In group A, Deniers questioned the validity of the new evidence, while Believers became more disheartened and fearful.

    • In group B, Deniers felt triumphant that they were right, while it was the turn of the Believers to question the validity of the new evidence.

What's happening?

  • When presented with new information, we tend to quickly accept evidence that confirms our existing notions (prior beliefs) and cast a critical eye on counter-evidence, trying to find faults with it.

  • This finding is not unusual. A similar experiment was conducted to gauge the views of supporter for the 2016 American elections: 2 groups of participants, each with supporters of Hilary Clinton and Donald Trump. Group A was told that recent polls had Clinton leading, while Group B was told that recent polls had Trump leading. And the results is exactly the same 

  • In fact, presenting people with information that contradicts their opinion can cause them to come up with altogether new counterarguments that further strengthen their original view - this is known as the “boomerang effect.”  Curiously enough, the more intelligent people are (admittedly by traditional measures like IQ tests), the more and capable they are to rationalize and interpret information at will, and to creatively twist data to fit their opinions. Ironically, intelligence is used not to draw more accurate conclusions, but to find fault in data they are unhappy with.

Why does this happen?

There are 3 major reasons why evidence is not able to change our minds. 

  1.   Confirmation Bias: Confirmation bias is the tendency to look out for and favour information that confirms/supports our existing beliefs. Many of us actually experience this daily. If we have a favourite sports team, personality, political affiliation, view on something, we want and are likely to read and remember pieces of news that support what we support. In fact, when we read news which supports our view, there is actual biological effect - your brain produces dopamine which makes you feel good; it justifies that you are right, and being right is awesome.  But it also means that we tend to ignore or discount evidence that is contrary to our view.  I was once with 2 friends who were basketball fans, debating on who was the greatest player ever - Michael Jordan or Lebron James. They presenting selected clips, statistics, and accomplishments of the player they supported while ignoring what the other person was presenting. While they were busy "arguing", I ignored both of them and ate up all the food meant for 3. A great night. 

  2.   Cognitive Dissonance: Cognitive dissonance is the discomfort we feel when there is an internal conflict. This conflict can be caused by new information that runs counter to our existing beliefs. Or when behaviour is the opposite of what we believe in. Just like confirmation bias, cognitive dissonance generates pain that can be biologically observed - parts of your that deal with pain activate much more when you have dissonance. What we tend to do then is to try and soothe, avoid, or explain this pain.  In the experiment above, we might choose to avoid dissonance by accusing the new information of being biased, with a hidden agenda. Or we could explain behaviour that runs contrary to our beliefs that it is a one-off or an exception. An example of this is even though you don't need to answer to anyone, you come up with an excuse to yourself when you don't do what you set out to. Cognitive dissonance is a major reason why we sometimes struggle to admit when we are wrong. 

  3.   The Dunning Kruger Effect: The Dunning Kruger effect is best summarised by the old adage - "A little knowledge is the most dangerous". People with just a little knowledge about a certain area tend to overestimate what they know. Folks who simply do not know enough to know what they don't know are paradoxically very confident of their own view. 

  4.   Amygdala triggerThe Amygdala is the part of the brain that regulates fear, anger, anxiety, and aggression (side-note: The Amygdala is a very influential and important part of our brain, involved in regulating a lot of our behaviour.  You can read more about the Amygdala here). Two major features of the amygdala are key here:
    1) the amygdala is triggered very quickly and subconsciously (i.e. it is triggered before you are even aware of it - which had been vital for our survival in the past)
    2) once triggered, it causes your body to recognise that potential danger is coming and that the body needs to go on the defensive. This includes not just physical defensiveness, but mental as well. When someone attacks our point of view or our belief, we are heavily inclined to start defending ourselves. 

A very good example of how 3 factors come together is anti-vaxxers, people who are against vaccines believing they would cause side-effects. This is contrary to science and in fact common sense - almost everyone in the developed world is vaccinated against some diseases, and suffer no side-effects. But we can see the confirmation bias kicking in because anti-vaxxers disregard the entire body of scientific and focus on a few unproven hyopethsis and selected anecdotes. We see the cognitive dissonance kick in when anti-vaxxers reject what their own doctors(who have treated them in the past) tell them. And most of all, we see the activation of the amygdala. Anti-vaxxers generally get quite emotional when talking about the vaccination - someone would almost certainly point out that they are wrong, which makes them angry and defensive. But this anger has its origins in fear - anti-vaxxer parents genuinely worry about their children and want the best for them. (this is a really important observation: because the amygdala regulates both fear and anger, a lot of times when we see an angry person, he/she is actually also fearful about something).

So if facts don't change minds, what does? What is the best way to convince an anti-vaxxer that he/she is wrong,

and is endangering their own child? Find out more in part 2 of this series: What works best to change people's minds?

I leave you with 2 final videos, on the lighter side of how difficult it is to change someone's mind, even in the face of the strongest evidence. 


That's not Mr Bean!

Video is 1 min 18s long

Where was he born?

Where was Barack Obama born? Somehow, this became a multi-year debate with a large number of conspiracy theories. Even after his full birth certificate was released, polls showed that up till 20% of Americans still do not believe that their President was born in America. It even sparked off its own Wikipedia page, and provided us with hilarious interview segments(excerpt from the daily show, full video here


Video is 1 min 11 secs long 

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