Confirmation Bias


Once we have our minds made up about something we have a strange way of protecting our point of view.  Confirmation Bias addresses this powerful mind trick we play on ourselves.


What is Confirmation Bias

Confirmation Bias is the answer to all kind of seemingly amazing occurrences in daily life.  We explain a lot away as coincidence.  For example, seeing three other cars the same as yours on the way to work; but is this so?  Could this simply be that we notice cars the same as our own?

It goes much deeper than this, inadvertently we trick and mislead ourselves as we look for information to support our own preferences.  Having dropped your mobile telephone rushing to work, resulting in a smashed screen you then spend the morning researching new mobiles.  Of course, you find one you like, it’s a bit pricey, but there’s no option.  You need to have a phone today.

When a coworker suggests that your smashed screen could be repaired you have no interest.  You have fallen in love with the new one you saw online, and besides the shop in town has one in stock; you can get it today.  Your now, potentially annoying, coworker explains that the same shop does phone repairs.  They probably would do it today, saving you a big expense.

Consider this as a bystander and you know the coworker makes sense.  The problem gets solved today without such huge expense.

Step back in as the person who has looked at new phones and you want none of it.  What will you come up with?

  • The phone wasn’t that good anyway
  • Once repaired it might break again
  • They may not have the parts
  • I can’t hand someone my phone
  • I’ve been thinking about an upgrade anyway

At this point, you have forgotten how good your current phone is; the broken screen allowed for.  Also how the expense of a new phone is not in your budget.  Perhaps, if your coworker had been there at the time you dropped the phone and said, ‘this can be repaired at lunchtime’ and ‘it’s not that expensive.’  You would not have researched a replacement, but now you have, and found one you like none of that ‘sensible talk’ will change your mind.  This is confirmation bias at work.


Confirm, Disprove or Ignore

These are the three main ways of bringing confirmation bias to life when information is received.


This is nice and easy for our needs, fuel for our fire.  Information that confirms our original thought or opinion, or at least it does the way we read it.  There are many ways that we hear things the way we want to.  A comedy sketch had one person asking, ‘am I right?’  The retort would be, ‘ you’re not wrong.’  That is not quite the same thing.


You could be at risk of being proved wrong, best get on and discredit the information.  You may find yourself needing to comb through several details to find the one that means the evidence before you is false.  Perhaps the underside of a chair has not been varnished; that’s it, I told you Ikea sold rubbish.  When a news reporter pronounces a place name differently, you can’t believe what they say, they don’t even know the name of the place.


Applicable to small and large details that if left alone would prove you wrong.  Small details can be easily glossed over.  Larger details may take a bit more work but the principle is the same; if you didn’t hear it, it can’t mean anything.  Remember seeing three cars like yours on the way to work.  What about the three cars like your neighbours?  This works into how we think of coincidence being a sign or having significance; we only notice coincidences relevant to us.


Confirmation Bias in Science

The field of science is well aware of the trap that can be fallen into.  Good practice requires that a hypothesis is presented prior to experimentation.  When a hypothesis is proven to be correct, the opposite is tested.  Disproving false findings is equally important as making findings.  Evidence comes from asking questions that have potential to disprove what you think, rather than only looking to support your expectations.


Test your questioning

I have four counters and lay them out in front of you as in the picture below.


I then explain that each counter has a shape on one side, you can see the square and star.  And a colour on the other side, you can see blue and orange.  Now I suggest there may be a pattern;  that if there is a square on one side, the reverse of the counter in always coloured blue.

To test this rule, how many counters do you need to turn over and which ones are they?

Chances are you will say the square and perhaps also the blue.  It is correct that you need to turn over the square, any colour other than blue would prove the pattern wrong.  However turning over the blue is of no use.  The suggested pattern read, that if there is a square the reverse is always coloured blue.  It did not say that a blue counter always has a square on the reverse.   We needn’t think about the star; even if the other side is blue this does not affect the pattern.  We should, however, check the orange.  If the other side presents a square the rule is proved wrong.

It makes sense when explained, so assuming you picked the square and blue, why did you do that.  Confirmation Bias; you look to prove the pattern correct rather than question it.


Destructive Confirmation Bias

Confirmation bias provides comfort, it protects us from the information we don’t want to hear.  One of my most worrying examples came during an initial hypnotherapy consultation for smoking cessation.  The client, a man, explained to me how his grandparents had both smoked 40 a day since the age of 14 years and both lived into their nineties.  For him, this proved that smoking did not cause health issues.  For background, the question I asked was, ‘what are your thoughts on your current level of smoking?’  By the end of the intake session, we agreed not to work together.

With an idea in mind, we naturally look for evidence to support it.  I have been in this trap myself on several occasions.  Do you read online reviews before making purchases?  Do you take more notice of 1 poor review or 5 good ones?  The stage at which you read the reviews has some influence.  If you are in the early stages of research the poor review may quickly move you along to an alternative product.  However, if you have researched the product and pictured yourself using it, with all the benefits the blurb promises that one poor review is going likely to have less impact on you.

New procedures brought in to the workplace that mean changes for the workers; I think we know where this is going.  And that could be a missed opportunity; this, of course, crosses over with our general dislike of change.


Circular Reasoning

This is a fantastic construct, viewed from afar it is a baffling but common occurrence.  Circular reasoning can perpetuate brand loyalty, ask a loyal customer.

Why do you always buy Heinz Beans?

Because they’re the best Beans

How do you know they are the best Beans?

Because I always buy Heinz

This is madness, if anything it proves the opposite; by always buying Heinz Beans they haven’t experienced other brands.  This can answer why some people end up paying over the odds as they support brands they believe in.  I am not endorsing Heinz Beans or suggesting they are overpriced; I really do not know.

If the above looks rather irrational, take a look at another example.

Why do you think VW cars are the best?

Becuase I only buy VW cars

So how can you be sure if you haven’t owned others?

Becuase I know they are the best

Skipping the second and third lines would technically lose no amount of certainty, however, to the VW owner they give their opinion factual basis.



The construct of confirmation bias is self-propagating.  When we look for evidence to support our opinions we will find it.  When other present information that goes against our opinions we play tricks on ourselves to disprove or ignore it.