cognitive bias / heuristic

Representativeness heuristic

This is not a diagnosis or a personality trait. A heuristic is a normal shortcut of the mind; a bias arises where it leads to a systematically wrong judgement. If you recognise yourself here, it is an invitation to gently check rather than to label yourself.

What it is

Membership in a category or a probability is judged by how closely a description resembles the typical image of that category.

How it arises and is maintained

The mind compares an object to a «type» stored in memory, instead of counting features or the base rate. This is a shortcut — it is fast. The distortion arises when resemblance to the image replaces probabilities and ignores the base rate. It is sustained because a vivid typical image comes to mind faster than dry figures.

How it may look

  • ««A quiet person with glasses is more likely a programmer than a salesperson», although there are many more salespeople.»
  • ««The description matches the image of success — so the outcome will be successful too».»

Soft signs in yourself

  • Judgement is built from resemblance to a type, without taking the base rate into account.
  • Resemblance to a vivid image outweighs the figures.
  • It is hard to account for the fact that there are simply fewer «typical» than «atypical» cases.
  • After a description, a category quickly appears, without checking the probability.

Questions for a Socratic dialogue

  1. What is the base rate of this category in reality?
  2. What in this description does not fit the type?
  3. If I set aside the resemblance to the image, what facts remain?
  4. What would change if I knew the category's share in the population?

Self-directed exercise

Account for the base rate

  1. Write down the description and the category you assigned it to.
  2. Estimate the base rate of this category in reality.
  3. List the features that do not fit the type.
  4. Formulate a judgement that takes both resemblance and base rate into account.

Core beliefs it may be linked to

  • ««Resembles the type — so belongs to that category».»
  • ««A vivid image is more accurate than figures».»
  • ««The base rate does not matter».»
  • ««If the description fits, the probability is high».»