Are random events perceived as rare? On the relationship between perceived randomness and outcome probability

Many daily life events, from lotteries to coincidental encounters, occur partly or entirely randomly or “by chance.” Six experiments, in two different languages, explored how perceptions of randomness are related to the perceived probability of the same events—specifically, whether low-probability events were viewed as more random than similar events that were judged (rightly or wrongly) to be more likely. The experiments suggest that low-probability outcomes of stochastic events are indeed considered as being more random than medium and highly likely outcomes, even when all are produced by a “blind” (hence random) process. Degree of randomness involved in catching a bus was inversely related to the subjective probability estimates of the same event, both for correct and incorrect estimates. Unlikely coincidences were perceived to be more random than the same events presented in a more likely frame. The outcome of a match between two soccer teams was deemed to be more random when the weaker team wins than when the stronger team wins. Only extremely deviant outcomes—for instance, a top student who fails on two successive exams—made some people reject the randomness account, presumably believing that such extreme events must have a causal explanation. We conclude that people generally associate randomness with low-probability events, indicating outcomes that “cannot be predicted.”