Psycho Wednesday #2 Clustering illusion

Clustering Illusion



“Clustering illusion” is a natural people’s tendency to perceive some pattern or „cluster” of data, but in fact there is no pattern. Elements in some system are always in some relation, so if there is a lot of elements we can always find something proving kind of regular pattern.


Clustering illusion is a very important cognitive bias, even in user experience area.

  1. When you design some interface is good to rememeber that people naturally look for some patterns, e.g. Elements close to each other, similar or with the same colors can be linked together by users. It is important during tests with users.
  2. It is very importnat in research field, especially in quantitative research. When you use single choice survey always remember to mix proper answers. People generally recognize that a long string of letters is unlikely and often they choose the wrong answer only to break the series.
  3. As a UX Researchers we are exposed to clustering illusion when we analysis research data. We have to look for user behaviour patterns carefully and remember about this cognitive bias.


Can you describe some case from your life or work when the clustering illusion apears?


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