Repräsentativitätsheuristik

Repräsentativitätsheuristik, often translated as representativeness heuristic, is a mental shortcut that people use to estimate the probability of an event. It involves judging the likelihood of something based on how well it matches a stereotype or a typical example of that category. People tend to believe that if something is similar to a prototype, it is more likely to occur or be a member of that category.

This heuristic can lead to several biases. One common bias is the neglect of base rates. Base rates refer to the overall frequency of an event in a population. For example, if someone is described as quiet, introverted, and enjoys reading, people might assume they are more likely to be a librarian than a salesperson, even though there are significantly more salespeople than librarians in the general population. The judgment is based on the stereotype of a librarian, not the statistical reality.

Another consequence is the conjunction fallacy. This occurs when people judge the probability of two events occurring together as greater than the probability of either event occurring individually. For instance, if presented with a scenario, people might rate the probability of "Linda is a bank teller and active in the feminist movement" as higher than "Linda is a bank teller," because the added detail aligns with a stereotype, despite the logical impossibility of this being true.

The representativeness heuristic is a useful and efficient cognitive tool, but its reliance on similarity and stereotypes can lead to systematic errors in judgment and decision-making. Understanding this heuristic helps explain why people sometimes make seemingly irrational probabilistic assessments.