Opinion-hasty-often can incline to the wrong side, and then affection for one's own opinion binds, confines the mind - Dante

If you are a leader in an organisation then it is likely that the effectiveness of your work is defined by the value of your decisions. And while most leaders try to be informed as possible (nobody actively wishes to make ill-informed decisions) the likelihood is, that you are constantly (and silently) beleaguered by blind spots.

What you may not know is that, in many cases, these blind spots are made in your own image.

A confirmation bias is the tendency to confirm, rather than falsify, your own hypothesis. Since Peter Watson conducted pioneering research in the 1960s, we know that humans put far more emphasis on evidence that corroborates their own beliefs, and pay far less attention to evidence that disputes them. The result is that their belief is always strengthened - regardless of its validity.

This would mean that a person who strongly believes that 'women are worse drivers' or that 'Americans are less polite' is (consciously or unconsciously) willing to only ever accept evidence that confirms these beliefs. And if blanket prejudice weren't enough, history has shown that when key decision makers are affected by confirmation biases, it can have disastrous effects for everyone involved.

1. Being clever

A common reason leaders suffer from confirmation biases is that, often, they just haven't accepted that they themselves can be susceptible.

We are all susceptible.

Testing has shown that confirmation biases are prevalent in all levels of intelligence. In fact, some psychologists even think that intelligent people are more susceptible.

A historical example of this is pre-scientific medicine. Bloodletting (the process of bleeding to relieve all manner of diseases and ailments) was prescribed by countless historical doctors and wise men. Bloodletting was almost never effective (and often did more harm than good). But confirmation biases meant that the failures were ignored and the successes (often the patient recovering naturally) were celebrated as vindications of the practice.

2. Memory failure

Let's try a thought experiment. In your own mind, answer the following question:

Based on the last year, on a scale of 1 - 10, how stressful is your job?

Hold on to the answer. We will come back to it shortly.

A large reason for confirmation biases in leaders is related to how we encode and recall memory. Testing has shown that our memory is naturally skewed to recall memories which confirm our thoughts and feelings, especially if those thoughts and feelings are felt particularly strongly at that moment in time.

When asked, how stressful is your job - depending on how stressed or satisfied you are at the current moment- you are likely to recall memories which confirm your current feelings. This means that your ability to neutrally recall memory to support or falsify beliefs will always be subjective.

3. Early evidence preference

A type of confirmation bias nearly all leaders are guilty of is the process by which we give undue weight to early evidence. By accepting early information, we risk creating a bias which affects our view of any later evidence. Some testing has shown that even when early evidence is later proven to be false, we still retain the original bias and our outlook is continually skewed.

This type of bias is particularly problematic in long complex court cases, and even in some police investigations. David Camm (now acquitted after 13 years in jail) was an unfortunate example of a police investigation and subsequent court case where early evidence was given preferential treatment and a subsequent bias was retained.

4. Discomfirmation bias

How often have you heard climate change-deniers claim that there isn't enough evidence to support global warming; or creationists who cite 'the missing link' as an argument against evolution? The fact is, the evidence for climate change is overwhelming, and the 'missing link' isn't so much a burning hole in the theory of evolution but a vastly misrepresented phrase that Charles Darwin used to convey a point over 150 years ago.

A disconfirmation bias is when we are presented with evidence which disputes our beliefs, and we then hold that evidence to a higher standard. We suddenly start to dispute the thoroughness or the impartiality of evidence, in a way we would never do for evidence which does not dispute our pre-conceived beliefs.

A disconfirmation bias is particularly tricky to spot because, in your own mind, it can give you the impression that you are indeed being thorough and scientific (just in an unfair way!)

5. Lies, damned lies and illusory correlation

Particularly problematic for leaders who have to spot trends in their organisation, a common confirmation bias comes in the form of line graphs and bar charts.

Humans are pattern-seeking mammals - and for the most part, this is a good thing. Being able to spot trends and relationships in the natural world is one of the reasons our species is so good at survival. However, this ability to see patterns sometimes misfires.

Illusory correlation describes a process by which we support our beliefs with non-existent correlations in any given set of data. Famous (albeit light-hearted) examples of this include a claim that the decline in Jack Sparrow-style pirates has resulted in the increase of global warming, and the rise in the sales of rock music has sparked the growth in the world's population.

The ability to shrewdly process data can set a leader ahead of the field. But sometimes even the most seemingly obvious correlations will always need further testing.

Avoiding confirmation biases

It should be stated that in all cases confirmation biases exist because we attempt to confirm our beliefs rather than falsify them. Adopting the scientific method and attempting to disprove yourself will normally negate most biases - but how do leaders ensure that they avoid biased decisions?

Common Purpose believes that the best leaders do this is by surrounding themselves with smart people who disagree with them - who cause them to question their decisions and why they have made them. Embracing diversity, and the heated debates and disagreements that diversity brings, is a sure-fire way of addressing biases within your own decision making.

How do you personally avoid confirmation biases? Or has a confirmation bias caused you to make a bad decision in the past? Let us know in comments below.

Common Purpose runs leadership development programmes that enable people from different backgrounds, sectors and geographies to work together to solve common problems. In the process, we give participants the inspiration, skills and connections to become better leaders, both at work and in society.

Founded in 1989 as a not-for-profit social enterprise, Common Purpose now runs local courses for leaders in cities across the world, and global programmes for leaders from over 100 countries across six continents. Each year, 4,000 leaders become Common Purpose alumni. Find out more