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Cognitive biases: challenging the way we think

02 August 2019 - By Paul Sills

Part 2

"A man sees what he wants to see, and disregards the rest"
— Paul Simon

Cognitive biases play a vital part in our daily decision-making processes. Due to the complexity of our brains, there is much contention surrounding how many cognitive biases there actually are. The number sits between 50 and 150 – all contributing to our everyday thinking. The five focused on in this and the next article are a selection of the main biases which appear most frequently throughout or lives.

This article will discuss the confirmation and anchoring biases. Evidence of these two biases are found not only in our everyday lives but within the law and areas of dispute resolution. Therefore, it is relevant and particularly interesting that we investigate these cognitive biases in order to better ourselves both professionally and as members of society.

Confirmation bias

American psychologist Raymond Nickerson defined confirmation bias asthe seeking or interpreting of evidence in ways that are partial to existing beliefs, expectations, or a hypothesis in hand”.

This occurs when we ‘cherry pick’ information which supports our preconceived beliefs, rather than researching and evaluating information from a range of sources and viewpoints. The failure to analyse information in an objective way often results in serious mis-judgements and uneducated decisions.

We are often so set on what we already believe that we only select and store information which supports that belief – we are not as open to information which challenges us as we think we are.

Confirmation bias in the law

Confirmation bias is prevalent in the criminal justice system. During the investigation process, it is easy for investigators to hone in on particular data and evidence which supports their theories, rather than exploring all possible alternatives. Their belief in their own intuition is often dangerous in that this confirmation bias allows for mistakes to be made, thus wrongful convictions.

Arrows drawn on post it notes

The conviction of Teina Pora can be used as a clear illustration of confirmation bias at play. The investigation and subsequent conviction of Mr Pora indicated a determination to legitimise pre-existing beliefs regardless of their validity.

Critics have argued that the police sought to build a case on his words rather than methodically evaluating the evidence and investigating other suspects. Police focused on Teina Pora from the beginning, ignoring other viable theories or evidence which disproved their preconceptions.

Despite the flaws in Mr Pora’s confession; being unable to identify Susan Burdett’s house, providing an incorrect description of her appearance and there being no physical evidence of Mr Pora’s presence in the house, police still persisted with their theory, determined to cement a conviction.

The quashing of Teina Pora’s conviction and Government apology in 2015 reinforces the part that confirmation bias played in the investigation and his conviction.

Why do good people make bad decisions?

The presence of confirmation bias in criminal investigations can be viewed on a wider scale to establish why good people often make poor decisions. There are two key reasons why people subconsciously use confirmation bias when making decisions:

  1. Confirmation bias is often evident because the human brain cannot carefully process all the information at hand. It is often the most efficient way to interpret information from one’s own viewpoint. Confirmation bias is instinctive, acting as a reflex in tough situations. Selecting and basing our decisions on information we have pre-stored in our brains saves time and energy, Therefore, when we are under a time constraint, confirmation bias shines through.
  2. Protection of self-image and self-esteem is another reason why confirmation bias is evident in our decision-making. It is important for our self-esteem that we ensure our preconceived ideas be proven to be correct – to be disproved can mean a blow to our confidence and egos. Therefore, we seek to find information which justifies our preconceptions in order to achieve self-gratification.

As a society, we are highly concerned with how we appear in the eyes of our peers. It is important to us that we are respected and taken seriously. Therefore, to appear to be making a quick, confident decision could be seen as being a depiction of strength and power.

Anchoring bias

Anchoring is the second significant cognitive bias I want to discuss.

This occurs where a person tends to rely on one form of data received, using this to shape their decision making. When we see something in a store which is on special, the original price is the ‘anchor’ thus – when we see it for 50% off we see ourselves as ‘winning’.

Psychologists have found that people tend to rely too heavily on one piece of information when making decisions rather than adopting a wider range. We see this in a variety of decision-making contexts from judicial sentencing, negotiations and medical diagnosis – it has been proven that people rarely make decisions which are very different from their starting (anchoring) point.

“People make estimates by starting from an initial value that is adjusted to yield the final answer” said Amos Tversky and Daniel Kahneman, reinforcing anchoring’s existence as being a limitation on our accurate decision-making processes.

Like all cognitive biases, anchoring comes as a result of the way our brains have been conditioned to process/store information. The primary cause stems from this need to begin with a starting point in our decision-making. It is easier for us to start with a figure or idea and base our decisions on that. Anchoring therefore prevents us from exploring and researching a variety of factors to come to a conclusion. In saying this, research has shown that even when branching out to explore alternatives, we still come back to our original anchors.

Furthermore, anchoring is caused by uncertainties. Decision-making is full of uncertainties and is a daunting task. As humans, we do not like making decisions without an influence of some sort.

It is preferable that our brains always have a starting point – a place to work from in our decision-making. Therefore, when making difficult decisions, prior values, memories and similar decisions become anchoring points to ease this uncertainty.

Often these prior occurrences/information which act as our ‘anchor points’ have little relevance to the situation at hand resulting in poor or unfulfilling decisions.

Anchoring appears in mediation when the opening ‘anchoring’ number offered in negotiation is used as a starting point for further discussion. Problems arise in this situation when the anchoring point is not an accurate valuation based on the facts of the case.

Studies have shown that the initial ‘anchoring’ number set out in negotiations have a substantial impact on the outcome of the negotiation. Those who make the first offer – setting the ‘anchor’ – end up being more successful over their opposition, ‘anchoring’ the discussions in their favour. This occurs even when the ‘anchoring number’ is seen by the other party(s) as being extreme.

It is evident that confirmation bias and anchoring have a substantial effect on our decision-making. It is vital that we recognise our biases in order to improve and enrich our thought processes. The next article will discuss the bandwagon effect, over-confidence bias, optimism bias and negativity bias as further key cognitive biases which affect our daily lives.


Paul Sills paul.sills@paulsills.co.nz is an Auckland barrister and mediator, specialising in commercial and civil litigation. He is an AMINZ Mediation Panel member. This is the second in a series of articles about Cognitive Biases. Read part one, part three and part four.

Last updated on the 2nd August 2019