
The representativeness heuristic occurs when we estimate the probability of an event based on how similar it is to a known situation. In other words, we compare it to a situation, prototype, or stereotype we already have in mind.
Representativeness heuristic example
You are sitting at a coffee shop and you notice a person in eccentric clothes reading a poetry book. If you had to guess whether that person is an accountant or a poet, most likely you would think that they are a poet. In reality, there are more accountants in the population than poets, which means that such a person is more likely to be an accountant.
Although representativeness provides a quick and efficient way to make decisions, it can cause us to overlook important information and draw incorrect conclusions.
The representativeness heuristic is a type of cognitive bias or mental shortcut. Just like other types of heuristics, such as the availability heuristic and anchoring bias, it can help us reduce the time and effort needed to make reasonably good judgments. At the same time, it can lead us astray because we only pay attention to a subset of information: in this case, similarity.
Under the representativeness heuristic, we estimate the probability of something belonging to a specific category based on the degree to which it resembles (or is representative of) the typical or average member of the category. This is called a prototype.
Example: Representativeness heuristic and prototypes
For many people, a stereotypical English literature professor is someone composed, with gray hair and a tweed jacket with elbow patches. If, on the first day of class, a person in jeans and a t-shirt comes in and introduces themselves as your new English literature professor, you might feel surprised. This is because they don’t resemble the image or stereotype of a professor you have in mind.
The problem with the representativeness heuristic is that we are unlikely to consider probabilistic or logical relationships between A and B when we have to answer questions like “What is the likelihood that A belongs to/originates from/generates B?” Rather, we judge based on whether A is representative of (meaning “similar to”) B.
In other words, the representativeness heuristic uses similarity instead of more complex probabilistic and logical explanations. For this reason, it can lead us to irrational biases, such as prejudice and stereotyping.
There are a few reasons that can explain why we draw on the representativeness heuristic to make judgments:
Under the representativeness heuristic, specific scenarios appear more likely than general ones because they are more representative of how we imagine particular events.
Example: Representativeness heuristic and detailed scenarios
Consider the following personality sketch:
Tom is 34 years old. He is intelligent but rather unimaginative, and he collects old jazz records. In school, he was strong in mathematics but weak in social sciences and humanities.
Which statement is more probable:
A. Tom is an accountant that plays the trumpet as a hobby
B. Tom plays the trumpet as a hobby
Given the description, you might feel that A is a more accurate answer. However, this violates a fundamental rule of probability. The conjunction, or co-occurrence, of two events (e.g., “accountant” and “trumpet player”) cannot be more likely than the probability of either event alone.
As the amount of detail in a scenario increases, its probability can only decrease steadily, but its representativeness (and thus its apparent likelihood) may increase.
This particular problem of representativeness is also known as the conjunction fallacy.
Although both the representativeness heuristic and the availability heuristic play a role in our decision-making and help us estimate how likely something is, they are two different types of heuristics.
In other words, representativeness causes us to miscalculate probability by paying more attention to similarity, while availability causes us to focus on ease of recall.