61 Behavioral Biases That Screw Up The Way You Think

1

Anchoring

The tendency to rely too heavily on one piece of information. For example when buying a used car, someone might focus too much on the odometer reading, rather than considering engine condition and other factors.

2 Attentional bias

When someone focuses on only one or two choices despite there being several possible outcomes

3Availability heuristic

Where people overestimate the importance of information that is available to them.

One example would be a person who argues that smoking is not unhealthy on the basis that his grandfather lived to 100 and smoked three packs a day, an argument that ignores the possibility that his grandfather was an outlier.

4 Availability cascade

A simple idea that gains popularity because of how simple it is, and then seems even more simple because of how popular it is. For example, claims that the earth is flat

5 Backfire effect

When you reject evidence that contradicts your point of view or statement, even if you know it's true.

6 Bandwagon effect

The probability of one person adopting a belief increases based on the number of people who hold that belief. This is a powerful form of groupthink.

7 Belief bias

A bias where people make faulty conclusions based on what they already believe or know. For instance, one might conclude that all tiger sharks are sharks, and all sharks are animals, and therefore all animals are tiger sharks.

8 Bias blind spots

If you fail to realize your own cognitive biases, you have a bias blind spot. Everyone thinks they're not as biased as people may think, which is a cognitive bias itself.

9 Choice-supportive bias

A bias in which you think positive things about a choice once you made it, even if that choice has flaws. You may say positive things about the dog you just bought and ignore that the dog bites people.

10 Clustering illusion

To conclude that data contains a "streak" or "cluster" when that set is actually random.

 For instance in basketball, the hot hand effect is the belief that a player who has hit several shots in a row is more likely to hit the next shot.

This is also called the gambler's fallacy, where one thinks a winning number is "due."

11 Confirmation bias

A tendency people have to believe certain information that confirms what they think or believe in.

12 Conservatism bias

Where people believe prior evidence more than new evidence or information that emerged. People were slow to accept the fact that the earth was round because they tended to believe earlier information that it was flat.

13 Curse of knowledge

When people who are smarter or more well informed can not understand the common man. For instance, in the TV show "The Big Bang Theory" it's difficult for scientist Sheldon Cooper to understand his waitress neighbor Penny.

14 Decoy effect

A phenomenon in marketing where consumers have a specific change in preference between two choices after being presented with a third choice.

15 Denomination effect

People are less likely to spend large bills than their equivalent value in small bills or coins.

16 Distinction bias

When you value two options differently when looking at them together rather than separately.

17

Duration neglect

When the duration of an event doesn't factor enough into a valuation. For instance we may remember momentary displeasure as strongly as protracted displeasure.

18 Empathy gap

Where people in one state fail to understand people in another state. If you are happy you can't imagine why people would be unhappy. When you are not sexually aroused, you can't understand how you act when you are sexually aroused.

19 Frequency illusion

Where a word, name or thing you just learned about suddenly appears everywhere. Now that you know what that SAT word means, you see it in so many places!

20 Galatea Effect

Where people succeed because they think they should.

21 Halo effect

Where we take one positive attribute of someone and associate it with everything else about that person or thing.

22 Hard-Easy bias

Where everyone is overconfident on easy problems and not confident enough for hard problems.

23 Herding

People tend to flock together, especially in difficult or uncertain times.

24 Hindsight bias

The tendency to see past events as predictable. "I knew all along Philip Phillips would win American Idol." Sure you did...

25 Hyperbolic discounting

The tendency for people to want an immediate payoff rather than a larger gain later on. Most people would rather take $5 now than $7 in a week.

26 Ideometer effect

Where an idea causes you to have an unconscious physical reaction, like a sad thought that makes your eyes tear up. This is also how Ouija boards seem to have minds of their own.

27 Illusion of control

The tendency for people to overestimate their ability to control events, like when a sports fan thinks his thoughts or actions had an effect on the game.

28 Illusion of validity

When weak but consistent data leads to confident predictions. Like one commenter noted on the MIT admissions blog:

Why is MIT's admissions process better than random? Say you weeded out the un-qualified (the fewer-than-half of applicants insufficiently prepared to do the work at MIT) and then threw dice to stochastically select among the remaining candidates. Would this produce a lesser class?

29 Information bias

The tendency to seek information when it does not affect action. More information is not always better.

30 Inter-group bias

We view people in our group differently than we would someone in another group.

31 Irrational escalation

Investing more money or resources into something based on prior investment, even if you know it's a bad one. "I already have 500 shares of Lehman Brothers, let's buy more even though the stock is tanking."

32 Just-world hypothesis

People wanting to believe that situations are guided by forces of justice, stability or order. People like to call this karma these days and call karma not nice names.

33 Less-is-more effect

With less knowledge, people can often make more accurate predictions.

34 Negativity bias

The tendency to put more emphasis on negative experiences rather than positive ones. People with this bias feel that "bad is stronger than good" and will perceive threats more than opportunities in a given situation.

This leads toward loss aversion.

35 bserver-expectancy effect

Our expectations unconsciously influence how we perceive an outcome. Researchers, for example, looking for a certain result in an experiment, may inadvertently manipulate or interpret the results to reveal their expectations. That's why the "double-blind" experimental design was created for the field of scientific research. 

36 Omission bias

The tendency to judge harmful actions as worse than equally harmful inactions. For example, we consider it worse to crash a car while drunk than to let one's friend crash his car while drunk.

37 Ostrich effect

The decision to ignore dangerous or negative information by "burying" one's head in the sand, like an ostrich.  

38 Outcome bias

Judging a decision based on the outcome over the quality of the decision when it was made. This is not accounting for the role luck plays in outcomes.

39 Overconfidence

We are too confident about our abilities, and this causes us to take greater risks in our daily lives.

40 Overoptimism

When we believe the world is a better place than it is, we aren't prepared for the danger and violence we may encounter. The inability to accept the full breadth of human nature leaves us vulnerable.  

41 Pessimism bias

This is the opposite of the overoptimism bias. Pessimists over-weigh negative consequences with their own and others' actions..

42 Placebo effect

A self-fulfilling prophecy, where belief in something causes it to be effective. This is a basic principal of stock market cycles.

43 Planning fallacy

The tendency to underestimate how much time it will it will take to complete a task.

44 Post-purchase rationalization

Making ourselves believe that a purchase was worth the value after the fact. 

45 Pro-innovation bias

When a proponent of an innovation tends to overvalue its usefulness and undervalue its limitations.

46 Procrastination

Deciding to act in favor of the present moment over investing in the future.

47 Reactance

The desire to do the opposite of what someone wants you to do, in order to prove your freedom of choice.

48 Recency

The tendency to weight the latest information more heavily than older data.

49 Reciprocity

The belief that fairness should trump other values, even when it's not in our economic and/or other interests.

50 Regression bias

People take action in response to extreme situations. Then when the situations become less extreme, they take credit for causing the change, when a more likely explanation is that the situation was reverting to the mean.

51 Restraint bias

Overestimating one's ability to show restraint in the face of temptation.

52 Salience

Our tendency to focus on the most easily-recognizable features of a person or concept. 

53 Seersucker Illusion

Over-reliance on expert advice. This has to do with the avoidance or responsibility. We call in "experts" to forecast, when in fact, they have no greater chance of predicting an outcome than the rest of the population. In other words, "for every seer there's a sucker." 

54 Selective perception

Allowing our expectations to influence how we perceive the world

55 Self-enhancing transmission bias

Everyone shares their successes more than their failures. This leads to a false perception of reality and inability to accurately assess situations.

56 Status quo bias

The tendency to prefer things to stay the same. This is similar to loss-aversion bias, where people prefer to avoid losses instead of acquiring gains

57 Stereotyping

Expecting a group or person to have certain qualities without having real information about the individual. This explains the snap judgments Malcolm Gladwell refers to in "Blink."  

58 Survivorship bias

An error that comes from focusing only on surviving examples, causing us to misevaluated a situation. For instance, we might think that being an entrepreneur is easy because we haven't heard of all of the entrepreneurs that have failed.

It can also cause us to assume that survivors are inordinately better than failures, without regard for the importance of luck.

.59 Tragedy of the commons

We overuse common resources because it's not in any individual's interest to conserve them. This explains the overuse of natural resources, opportunism, and any acts of self-interest over collective interest. 

60 Unit bias

We believe that there is an optimal unit size, or a universally-acknowledged amount of a given item that is perceived as appropriate. This explains why when served larger portions, we eat more.  

61 Zero-risk bias

The preference to reduce a small risk to zero versus achieving a greater reduction in a greater risk. 

This plays to our desire to have complete control over a single, more minor outcome, over the desire for more — but not complete — control over a greater, more unpredictable outcome.