Investor Minute
Pigeons, Monte Hall, and the cost of bias
It’s pretty obvious that birds have much smaller brains than humans. In fact, calling someone a birdbrain is considered an insult.
Yet, research has shown that even though birds lack the analytical abilities of humans, they are superior to people in certain kinds of decision making. The evidence is in how our two species perform when solving the “Monte Hall” problem.
Monte Hall was the host of the long running gameshow “Let’s Make A Deal.” During the show a contestant would be presented with three doors. Behind one was a valuable prize. Behind the other two were goats. The items were placed randomly behind the doors and stayed there throughout the game. After the contestant made a guess, Hall would open one of the doors he knew did not conceal the prize. This would leave two closed doors, one with the prize, the other with a goat. The contestant would then be given the chance to change their original door number guess.
Most people would opt to stay with their initial choice, despite the fact that switching actually doubled their chances of winning.
It’s simple probability. The odds of getting their first choice correct is 1 out of 3, which doesn’t change after the host opens a wrong door. If the probability of the first choice being correct remains the same, and there are now two doors left, then by choosing again, the odds of getting the correct door go up to 2 out of 3.
Even though simple computer modeling shows this to be true every time, most people find this strategy completely illogical. Pigeons, on the other hand, can grasp the concept relatively quickly.
In a study that had pigeons repeatedly trying to solve the Monte Hall problem for food, within a month they learned that changing their second guess improved their chances of winning. Human subjects playing the game a similar number of times did not.
The reason for this, researchers found, is that people tend to be biased against switching. It violates a basic rule of thumb we use as a shortcut to solving logical problems. Pigeons, however, have no such bias and so are able to approach the problem empirically—meaning they learn the solution after looking at repeated outcomes.
Why is this useful to know?
You probably won’t end up as a contestant on “Let’s Make A Deal,” but you will face situations as you invest for retirement where the disciplined strategy seems to go against common sense and decades of empirical evidence. When markets are volatile and temporarily declining, your emotions will be telling you to take action, but your plan, your best chance for long-term success, should remind you to follow the evidence and stay the course.
Your trusted advisor can give you an unbiased perspective on what’s best for your unique situation, as well as help you make decisions that are in your best financial interest. Schedule a free call with us today.