Confirmation bias

Nassim Nicholas Taleb, writing in The Black Swan:

“Cognitive scientists have studied our natural tendency to look only for corroboration; they call this vulnerability to the collaboration error the confirmation bias.

The first experiment I know of concerning this phenomenon was done by the psychologist P. C. Wason. He presented the subjects with the three number sequence 2, 4, 6, and asked them to try to guess the rule generating it. There method of getting us to produce other three number sequences, to which the experimenter would respond “yes” or “No” depending on whether the new sequences were consistent with the rule. Once confident with their answers, the subjects would formulate the rule. … with the correct rule was “numbers in ascending order,” nothing more. Very few subjects discovered it because in order to do so I had to offer a series in descending order (what the experimenter word say “no” to). Wason noticed that the subjects had a role in mind, but gave him examples aimed at confirming it instead of trying to supply series that were inconsistent with their hypothesis. Subjects tenaciously kept trying to confirm the rules that they had made up.”

Peter Cathcart Wason‘s 2-4-6 problem proved that we have a tendency to seek out evidence which confirms our ideas rather than that which falsifies them.

Alvin Toffler echoed a sentiment, and borrowed a fair amount from Leon Ferstinger‘s concept of cognitive dissonance, 10 years later.

Nate Silver writing in The Signal and The Noise:

“Alvin Toffler, writing in the book Future Shock in 1970, predicted some of the consequences of what he called “information overload”. He thought our defence mechanism would be to simplify the world in ways that confirmed our biases, even as the world itself was growing more diverse and more complex.”

Silver later sums up the bias succinctly:

“The instinctual shortcut that we take when we have ‘too much information’ is to engage with it selectively, picking out the parts we like and ignoring the remainder.”