List of Cognitive Biases.

This list of biases and heuristics can be considered your shopping list of insights that at any point you could pick up and start trying.

The Bias List

Adaptive Bias

When there is little information, a decision can be based on the cost of being wrong. The brain has evolved to reason adaptively, in an attempt to reduce the cost of cognitive errors, rather than the frequency.

Affect Heuristic

A decision making shortcut that relies on emotion over logic.

Affordance Cues

Cues that indicate how you might act, as a door handle indicates you can open the door.​

Ambiguity Aversion

This is the likelihood of choosing a known risk over an unknown risk.


An anchor is a piece of information that precedes a decision and acts as a starting point for the decision, even if the first piece of information is incorrect, illogical or unconnected.

Authority Bias

The tendency to give greater importance to the opinions or statements of those in authority, irrespective of their knowledge, skill or true authority.

Availability Heuristic

When creating a mental projection, people will use things that more easily come to mind, this is often the vivid, emotional or unusual stuff.

Base-Rate Fallacy

The tendency to disregard the 'base' information and instead focus on smaller more specific information.

Broken Window Effect

Signs of anti-social behaviour encourage more anti-social behaviour.​


A well-known term. This is being selective in the information that you choose to consider.

Choice Paralysis

When given a challenging selection of choices, it becomes very hard to make any decision at all. Here a short-cut decision is likely to be made (either do the 'default' thing or do nothing).​


It often has strong benefits to reduce large tasks into smaller, related chunks. Smaller chunks are seen as less daunting and are therefore more likely to be completed.

Clustering Illusion

Overestimating the importance of small patterns in large samples of random data.​

Cocktail Party Effect

Ever deep in conversation then you suddenly tune in to someone talking about you from across the room? This is the power of grabbing our attention with personalisation.

Cognitive Ease

Easy is better, nearly always. If there's a choice between easy and easier, easier is more likely to be the chosen direction.

Cognitive Dissonance

The state of inconsistent thoughts, beliefs or attitudes, beyond your present knowledge.​


We like to look committed. This has been used successfully with customer services that repeat a task back to a customer as a question, once they confirm, they're more likely to complete the task. "So you're able to complete that form?" "Yes" - gotcha!​


Perhaps unsurprisingly we process the concrete over the abstract with much greater ease. This means it's likely that 'Save £10' is a stronger message than 'Save money'.

Confirmation Bias

Interpreting information in a way that confirms your preconceptions.

Conjunction Fallacy

The assumption that specific conditions are more likely than general ones.

Contrast Effect

The change of perception in relation to contrasting objects.

Costly Signalling

The idea that because a communication strategy costs a lot of money (heavy weighted envelopes, large street ads...), it may increase the potential for the messaging to be a success as there is an assumption that only really good things are worth that amount. The cost can also be in time or energy/effort.

Default Effect

Choice paralysis; when given the choice, people favour the default option.

Effort Justification

The tendency to attribute a higher value to something that has or will take more effort than the truer value of the effort afforded.

Endowment Effect

Considering something to be your own leads to the tendency to create a higher worth for it than you'd give it if you didn't own it.

Whether you're trying to get customers to switch from a competitor, to buy a greater range of products or to pay a premium, businesses need to understand behaviour change.

Behavioural science - the study of how to effectively change behaviour - should therefore be a topic all businesses are interested in. There are many areas that behavioural science can be applied commercially, with music and atmosphere being some of the least exploited.

Startle are at the forefront in this area.

Richard Shotton

Consultant and author of the choice factory

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Richard Shotton

Extremeness Aversion

This is the propensity to avoid making what could be deemed an extreme choice as this would be of higher risk to your social credentials or safety.

Expectancy Theory

What we expect to experience can change our subjective evaluation of what we experiences. In short, expect it to the bad, you'll think it was bad, expect it to be great, you'll think it was great!

False-Consensus Effect

The tendency to overestimate how much other people agree with them.

Fear of Regret

What it says on the tin, the fear of regretting a decision.

Forer Effect

The tendency to propose a high accuracy to vague descriptions of 'them', that could, in fact, describe anyone. This is the basis of fortune telling and personality tests.


Using the context of information in a way as to create new meaning.

Fundamental Attribution Error

The tendency to overemphasise internal factors, such as personality, taste, emotional status for the reason behind a decision or action, rather than external factors that may indeed have a much greater impact on the decision or action.

Gambler's Fallacy

Ever got stuck on a roulette machine, thinking about your chances of winning next time around? This is the belief that past events have an influence on future probabilities.​

Goal Gradient

Ever noticed that you speed up the closer to completing a goal? Well, you do, so there.


The desire for harmony in a group, which leads to dysfunctional decision making.

Halo Effect

The knock-on of one positive impression to another potentially unconnected piece of information. This is also known as Source Effect, particularly in relation to influencer or celebrity endorsement.

The Hawthorne Effect / Observer Effect

People act differently when they are being watched. This can obscure test results and experiments. If you want to remove this effect (as best as possible) set up the research as a field or natural experiment.

Hyperbolic Discounting

You can have one sweet now, or the whole bag in 3 months. What do you choose? This is the tendency to prefer immediate payoffs relative to later payoffs.

Ikea Effect

Attaching a higher value to things you have made in part by your own efforts (actual or perceived).

Illusion of Attention

People falsely believe that they are taking in everything that happens in front of them, rather than just the information they are focusing on.

Illusion of Control

The overestimation of your control over external factors.

Illusion of Skill

Overestimating skill over chance.

Illusory Correlation

Seeing a correlation between two unconnected pieces of information.

Illusory Superiority

Overestimating your positive attributes and underestimating your less desirable qualities relative to other people. "I know I'm grumpy, but they're much more grumpy than me..." (says the grumpiest person you know).

Inductive Thinking

Perceiving universal 'truths' from individual observations.

In-Group Out-Group Bias

Favouring members of your own 'group' over members of other 'groups'. The definition of the group can be very arbitrary.

Introspection Illusion

The illusion that you have insight into your own mental states when this is often not true, and treating others introspections with scepticism.​

Labour Illusion

Going the extra mile. Classic sales technique. The reason being, we value things more highly when we perceive greater effort has been taken on your behalf.

Liking Bias

Being more susceptible to the ideas of someone you like.

Loss Aversion

The pain of giving up something is greater than the joy of acquiring something. Losses weigh heavier than gains.

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Measurability Bias

Being biased towards data due it being measurable, rather than it truly being of use. Just because it can be measured doesn't make it useful information. Of course, the opposite is also true.

Motivation Crowding

Outside awards or motivations such as money or punishments can undermine intrinsic motivations.

Neglect of Probability

Disregarding probability when making an uncertain decision.


To be obsessed with the new.

Not-Invented-Here Bias

An aversion to things or information that stems from a place considered 'other'.

Outcome Bias

Judging decisions on the outcome of the decision, rather than the depth and quality of the decision making process.

Peak-End Rule

The tendency to perceive an experience by an average of its climax and stand our moments, rather than on the whole.

Planning Fallacy

The underestimation on how long tasks may take to complete.​

The Pratfall Effect

We are actually more likely to trust, believe and like things that admit error or seem more fallible. Admitting a product downside could actually increase the likelihood of purchase as instead of wondering where the 'hidden downside' is (and whether it'll cause a big problem) a customer can easily overcome the known downside as it reduces the risk of it being bad (beyond the known risk).

Present Bias

Spend £20 now on some new shoes, or save £20 a month forever and have a better pension pot? We are more likely to favour shorter gains over longer-term gains. This makes pension savings a tough call.

Primacy and Recency Effects

In a long list of items, the things at the beginning and end are likely to be remembered most vividly. (So if you're reading this whole list of biases, this is the middle section that you're less likely to remember later on...)

The Query Effect

People are able to make up an opinion about anything when asked. It doesn't mean that their answer will truly represent their actions, intentions or decision-making processes. This can be the source of useless insight.


Feeling obliged to reciprocate.​

Regret Aversion

If you think there's a fair chance you'll regret a decision, you'll likely aim to reduce the chance of regret.​

Representativeness Heuristic

Judgements that are based on similar issues that are considered known quantities. The 'illogical' thought here is that like goes with like and that cause and effect should be the same.

Salience Effect/ Von Restorff Effect

Things that are distinctive stand out from their 'peers' and are more likely to be remembered.

Self-Serving Bias

The assumption that anything scarce is valuable.

Scarcity Error

The tendency to stake more of a claim to successes than failures.

Social Proof/ Herd Instinct

Baa! This is the tendency to follow the crowd. 🐑

Story Bias

The power of a narrative to elevate information.

Subjective Validation

Giving the status of truth to something that is really belief-based thought, this can give meaning to unrelated or coincidental occurrences.

Sunk Cost Fallacy

In investment terms, people tend to justify further investment into something based on having already invested (even though this original investment may have been wrong). In for a penny, in for a pound!

Zeigarnik Effect

This is where-
This is where interrupted or incomplete tasks can be better-
This is where interrupted or incomplete tasks can be better remembered than complete ones, potentially as the status of being incomplete causes tension.

Long list Fatigue Effect!

Okay, that's not a real one. But if you've gone through this whole list you deserve a Mars bar and a coffee.