Fallacies of Thinking No.3 - ‘Gambler's Fallacy’

Humans are less than perfect decision makers. There are a number of ‘fallacies’ of thinking we fall prone to. Today we take a look at a phenomenon called ‘Gambler's Fallacy.’

A tossed coin has a 50/50 chance of landing on either ‘heads’ or ‘tails’.

But what is the chance of a coin that has landed ‘heads-up’ nine times in a row landing on ‘heads’ the tenth time it is tossed?

Exactly the same.

50/50.

Like me, you were probably thinking that it was far more likely for the next toss to land ‘tails-up’ right?

The past series of results, though, has no effect on the probability of the various possible outcomes of the next coin toss.

This is known as the ‘Gambler’s Fallacy.’

Next time you’re having a flutter at the casino remember that previous results have nothing to bear on what will happen next.

As the French mathematician Joseph Bertrand wryly said, "The coin has neither memory nor consciousness." 

Learn about more fallacies of thinking by checking out our previous post on the ‘Neglect of the absent’ and the ‘Bandwagon Fallacy’.