What psychological phenomenon describes the misconception of probability when considering two events together rather than separately?

The conjunction fallacy is a psychological phenomenon wherein people incorrectly believe that the conjunction of two events is more probable than either event occurring alone. This is particularly evident when individuals ignore the basic principles of probability and fail to recognize that the likelihood of two specific conditions being true simultaneously must be less than or equal to the probability of either one being true on its own.

For instance, if presented with a scenario involving a character who is described in detail, many will mistakenly judge that this character is more likely to be a bank teller and a feminist than just a bank teller alone, despite the fact that the probability of both conditions being true cannot exceed the likelihood of just one. This misjudgment stems from how people assess information and make decisions based on representativeness rather than statistical reasoning.

The other options relate to different cognitive biases or principles. The law of large numbers pertains to the outcome of events as sample sizes increase, availability bias emphasizes how easily examples that come to mind influence perception of frequency, and the representativeness heuristic involves making judgments about the probability of an event based on how much it resembles typical cases. While relevant, none of these concepts directly capture the idea of perceiving the probability of jointly occurring events incorrectly, which is the essence of the conjunction