Playing roulette (in a fair game), the ball lands on 9 black numbers in a row. Is the next spin more likely to be either black or red? Some players mistakenly think it must be red’s turn after seeing 9 blacks in a row, when infact it is equally more likely to be red or black. This fallacy may cause them to unnecessarily lose money, as they place bigger bets on red the more often they see blacks.
Definition of gambler’s fallacy
The gambler’s fallacy is the inaccurate idea that if an event has occurred more often in the past than they might expect, it will occur less often in the future. Alternatively, if an event has occurred less often in the past than they might expect, it will occur more often in the future.
The gambler’s fallacy in action in Monte Carlo in 1913
This fallacy is often also refered to as the Monte Carlo fallacy, as in August 1913 26 blacks occurred in a row on a roulette wheel at Monte Carlo Casino – while this happened, a lot of money was lost by players incorrectly thinking red was due and placing big bets.
The past is not an indicator of the future
The flaw with this idea is that every spin in roulette is independent – the game does not remember what has happened before. That is to say you cannot look at past results, and use this to predict the future. If the wheel lands on 5 black numbers in a row, the next spin is still equally likely to be either black or red. There are no patterns you can look out for, and base your betting system on.
Reverse gambler’s fallacy
The Reverse Gambler’s fallacy, is the idea that just because there has been 9 blacks in a row, the next spin is more likely to be black. Again, due to independence of every spin, if you decide to bet bigger than usual on the next spin being a black, this is a bad strategy.
However, given the next spin is 50-50 to be red or black if the equipment was fair, given the small chance there may be a problem with the equipment (or software), we would actually recommend betting on black in this case if you were going to be placing a bet anyway (this is a rational decision) – just don’t bet bigger than usual as that would be falling for the fallacy!
