One of the doors you didn’t pick is opened, let’s say the red door, to reveal no prize.
You now have a choice. Stick with yellow? Or swap for the blue door?
It seems counter-intuitive but switching doors doubles your chance of winning.
Researchers in America found that humans rarely changed their minds – even after they had been trained and given explanations – and therefore performed poorly, whereas pigeons learned to adopt this strategy to optimise their “winnings”. (Journal of Comparative Psychology Vol 124 No 1)
Originally posted May 28 2010