Looking for, remembering, noticing or giving more weight to data that supports an existing view. This includes rejecting new evidence that contradicts our current thinking.

Group thinking, going with the flow of the crowd or not thinking independently, and is often based on a conscious or unconscious desire to fit in.

Over-emphasising pleasing outcomes, whilst failing to identify limitations and weaknesses. This might come about through evaluating ambiguous information in a favourable light. It might also take the form of requiring a higher standard of evidence for a negative conclusion, whilst accepting a lower standard of evidence for a positive conclusion.

The opposite of optimism bias, where we over-emphasise negative events or outcomes. This can include ‘negativity bias’, where we perceive criticism or bad news as being more important, profound or trustworthy than praise or good news.

Where we prefer to do what we have always done simply because we have always done it that way (‘status quo bias’), or alternatively where we prematurely approve of a proposal simply because it is new and modern (the ‘appeal to novelty’ fallacy).

Claiming more personal responsibility for successes than for failures.

The tendency to overestimate the importance of small runs, streaks or clusters in large samples of random data. This is also known as seeing ‘phantom patterns’.

When we become aware of something, we start to see it everywhere and believe that it’s becoming more common or prevalent (when in fact it’s just that we are noticing it more).

The natural human desire not to ‘say the wrong thing’. This is particularly important to be aware of when collecting self-report data, using tools such as surveys, focus groups or interviews.