Noise: A Flaw in Human Judgment

by Daniel Kahneman

also changes how you think.

Being in a good mood is a mixed blessing, and bad moods have a silver lining.

The costs and benefits of different moods are sit...

negotiators who shift from a good mood to an angry one during the negotiation often achieve good results—

good mood makes us more likely to accept our first impressions as true without challenging them.

People who are in a good mood are more likely to let their biases affect their thinking.

propensity to find meaning in such statements is a trait known as bullshit receptivity.

Inducing good moods makes people more receptive to bullshit and more gullible in general;

eyewitnesses who are exposed to misleading information are better able to disregard it—and to avoid false testimony—when they are in a bad mood.

important truth: you are not the same person at all times.

In short, you are noisy.

prime suspects: stress and fatigue.

Even the weather has a measurable influence on professional judgments.

Another source of random variability in judgment is the order in which cases are examined.

implicit frame of reference.

lean toward restoring a form of balance:

a cognitive bias known as the gambler’s fallacy: we tend to underestimate the likelihood that streaks will occur by chance.

are not always the same person, and you are less consistent over time than you think.

“We were struck by how much variability remained after removing the effects of our predictor variables.”

the moment-to-moment variability in the efficacy of the brain is not just driven by external influences, like the weather or a distracting intervention.

our neurons never operate in exactly the same way.

Every day, similar groups make very different decisions,

because of group dynamics, groups can add noise,

proposition holds whether we are speaking of noise across similar groups or of a single group whose firm judgment on an important matter should be seen as merely one in a cloud of possibilities.

testing for a particular driver of noise: social influence.

The key finding was that group rankings were wildly disparate: across different groups, there was a great deal of noise.

song benefited from early popularity,

success in the social influence condition was more unpredictable than in the independent condition.”

popularity is self-reinforcing.

The result was that most of the unpopular songs became quite popular, and most of the popular songs did very poorly.

single exception is that the very most popular song

For the most part, however, the inverted ranking helped determine the ultimate ranking.

groups might end up making very different judgments simply because of who spoke first

initial burst of popularity is self-reinforcing, and if a proposal attracts little support on the first day, it is essentially doomed.

political positions can be just like songs, in the sense that their ultimate fate can depend on initial popularity.

You might well think that after hundreds or thousands of visitors and ratings, a single initial vote on a comment could not possibly matter. That is a sensible thought, but it is wrong.

you take a large group of people and ask them a question, there is a good chance that the average answer will be close to the target.

independence is a prerequisite for the wisdom of crowds.

social influences are a problem because they reduce “group diversity without diminishing the collective error.”

studies we are describing involve informational cascades.

That is the central finding of the music download experiment (and its cousins).

truculent,

they do not want to look disagreeable or silly.

Their agreement might be a product of social pressures, not of conviction.

Very similar groups can end up in divergent places because of social pressures.

study of juries uncovers a distinct kind of social influence that is also a source of noise: group polarization.

Internal discussions often create greater confidence,

greater

unity, and greater e...

frequently in the form of increase...