# On Confirmation Bias

Last week I ran a simple experiment on Twitter, inviting people to find a pattern in a three-number sequence. The numbers were 6–12–18. In order to solve it, people had to do two steps. First, propose their *own *sequence of three numbers that would conform to the pattern they thought I was thinking of. They could propose as many three number sequences as possible, and for each one I would tell them if it fit the pattern I had in mind or if it didn’t. When they were satisfied that they understood the pattern, they could guess what it was, but only got one guess.

As I predicted, people had an extraordinarily difficult time guessing the pattern that I was thinking of. Over the course of about four hours, I’d say about 40 people sent me DMs with guesses. Nearly all of them submitted three-number sequences that worked. All but two of them guessed patterns that were wrong.

The pattern I had in mind was simple: any three numbers in ascending order. Overwhelmingly, people who submitted answers suggested it was something more complex: intervals of 6, multiples of 6, the third number being the sum of the first two, etc. Almost everyone only submitted a single number of sequence of their own before attempting to guess the pattern. Since their submissions all fit the simpler pattern I had in mind, they all assumed their more complex pattern was right, and then nearly all of them processed to…