The Gambler's Fallacy

On August 18, 1913, at a casino in Monte Carlo, the ball on a roulette wheel landed on black twenty-six times in a row. As the streak grew longer, gamblers at the table grew convinced that a run on red was overdue, and many bet heavily on red, certain the wheel was due to correct itself. Some players lost considerable sums before the streak finally broke. This behavior illustrates what is now known as the gambler's fallacy: the mistaken belief that if an independent random event has deviated from its typical pattern recently, the opposite outcome becomes more likely in order to balance things out. In reality, for a fair roulette wheel or a fair coin, each spin or flip is statistically independent of every previous one. The wheel has no memory of the twenty-six previous spins, so the probability of black or red remains essentially the same on the twenty-seventh spin as it was on the first. Psychologists studying decision-making later identified this same reasoning pattern well beyond casinos, noting its influence on investors who assume a stock is "due" for a reversal after a long streak, and on everyday judgments about weather and sports outcomes, where people intuitively expect randomness to self-correct even when each event remains independent.