Thinking Flaws

A collection of all thinking flaws - cognitive biases, fallacies, psychological weirdities and more.

Every cognitive bias is there for a reason - primarily to save our brains time or energy. If you look at them by the problem they’re trying to solve, it becomes a lot easier to understand why they exist, how they’re useful, and the trade-offs(resulting mental errors) that they introduce.

Cognitive Biases addresses these issues...

1. Information overload

Our brain filters out information that it thinks is not important. There is too much information available - its not practical to process all of it.

Notice only that are primed or repeated

  • Attentional bias: What we believe/want influences what we focus on/notice.
  • Availability Heuristic: You overestimate the probability of something that you hear more often/remember easily.
  • Context effect: We might not be able to recall information without memory aids/cues that we used at study.
  • Frequency illusion: Once you learn a new word/concept, you see it everywhere.
  • Hot-Cold Empathy Gap: There is a significant difference in how we act in an emotionally charged state(hot state) when compared to your normal state(cold).
  • Illusory truth effect: We believe incorrect information to be correct after repeated exposure.
  • Mere-Exposure Effect: Psychological phenomenon by which people tend to develop a preference for things merely because they are familiar with them.
  • Recency bias: More weightage is given to a recent event/data/evidence when compared to past events/data/evidence.

Bizarre/funny/visually-striking/anthropomorphic are more Noticeable

We generally skip information that's ordinary or expected.

Change is Noticed Prominantly

  • Anchoring Effect: Choices are affected by an anchor.
  • Framing effect: People's choices can change based on how the question is framed or worded.
  • Distinction bias: When evaluating between two options, we view them as very different - as compared to evaluating them separately(we would have evaluated them very close to each other).
  • Weber–Fechner law: Perceived difference is not the same as actual difference.

Drawn to details that confirms existing beliefs

And ignore/miss details that contridicts our beliefs

We notice flaws in others easier than in ourselves.

  • Bias blind spot: It's more difficult to notice biases in ourselves.
  • Naive Cynicism: Expecting others to be biased all the time.
  • Naive realism: Belief that our view of the world is objective, and people who disagree are irrational/biased/misinformed.

2. Not enough meaning

The world is too complex to understand fully. So we compensate by filling in the gaps of our understanding to make better sense of it - or at least have a belief that we have an understanding of the world. We assign meaning to the world - we do our own sensemaking.

We find patterns and meaning even with little data

Our brain needs to feel that it has a coherent model/story about the situation - even if we have too little information about it.

  • Anecdotal fallacy: We believe that personal experience/anecdotal examples trumps data or logical argument.
  • Anthropomorphism: Assigning human traits, attributes, emotions or agency to non-human things.
  • Clustering illusion: Belief that streaks or clusters in parts of random data are non-random.
  • Gambler’s fallacy: If an unlikely event(that's statistically independent) occurred multiple times, it's less likely to occur in the future.
  • Hot-hand fallacy: Belief that someone who has been successful will be more likely to be successful in future attempts.
  • Illusion of validity: Overestimation of ability to interpret and predict outcome when analyzing data that shows a consistent pattern.
  • Illusory correlation: Perceiving a relation between things(people, behaviors, events, etc) when no such relation exists.
  • Insensitivity to sample size: People tend to ignore sample size of data. They forget that variation is more likely in smaller sample sizes.
  • Confabulation: Memory error - people sometimes have wrong/distorted memories that they are confident about.
  • Neglect of probability: Tendency to ignore probability when making decisions in uncertain conditions.
  • Pareidolia: Seeing a pattern/meaning where there is none.

We jump to conclusions using stereotypes, generalities, past occurrences.

When we have only limited information/gap in knowledge we tend to fill in the gaps using best guesses from stereotypes and generalities. Once its done, we can't easily determine which part is real and which part is filled up.

  • Argument from fallacy: The idea that since an argument had a logical fallacy in it, it must be false.
  • Authority bias: We believe that the views of an authority figure(Eg. God, Govt, Parent) is more accurate - and let it influence our options.
  • Automation bias: Tendency to believe decisions from an automated decision making system have more accuracy. And even ignore contradictory information made without automation.
  • Bandwagon effect: Tendency to follow the crowd. Adopting behaviors, practices, attitudes, beliefs only because others are doing it.
  • Essentialism: Philosophical view that all things have a set of properties that are necessary to their identity.
  • Functional fixedness: Cognitive bias that limits your imagination of how an object can be used to only its traditional use.
  • Group attribution error: Belief that the characteristics of one person in a group must be there in all.
  • Just-world hypothesis: Belief that people will get what they deserve. Or Everything happens for a reason.
  • Moral credential effect: A previous 'good' behavior will make it easier to do 'bad' behavior.
  • Placebo effect: An inert pill can cure health issues if the patient believes that it will.
  • Stereotyping: General belief about a group of people - and expects that belief to be true of all individuals in the group.
  • Ultimate attribution error: Explains the negative behaviors of outgroup(others) to personality defects and negative behaviors of the ingroup(us) to external circumstances or chance.

Belief that liked or known things are better

Belief that people/things we like or familiar with are better than that we don't like/are familiar with.

Simplification of Probability and Numbers

Subconscious mind is bad at maths - and uses simplification to optimize decision making. This can get wrong results.

  • Appeal to probability fallacy: Belief that if it's possible, then it's probable.
  • Base rate fallacy: We tend to overvalue the specific information - rather than integrating it with general information like the base rate.
  • Conservatism: People don't easily change existing belief even when presented with new evidence.
  • Denomination effect: Less likely to spend a large denomination currency than the equal value in smaller notes.
  • Hofstadter’s law: It describes the widely experienced difficulty of accurately estimating the time it will take to complete tasks of substantial complexity.
  • Hofstadter’s law: It always takes longer than you expect, even when you take into account Hofstadter's Law. It describes the widely experienced difficulty of…
  • Magic number 7+-2: Number of items that can be held in short term memory: 7 +/- 2
  • Mental accounting: People tend to assign subjective value to money - this is susceptible to biases, thinking flaws.
  • Money illusion: People mistake the face value of money(the amount of money) with the real value(what it can buy).
  • Normalcy bias: The brain sometimes ignores multiple warnings signals.
  • Subadditivity effect: Belief that probability of the whole is lesser than the sum of probabilities of the parts.
  • Survivorship bias: Concentrating on the people/things that got past a selection point.
  • Swimmer’s body illusion: People confuse selection factors with results.
  • Time-saving bias: We underestimate time saved when moving from a relatively smaller speed to higher speed. Also, we overestimate time saved when moving from a relatively faster speed to even faster speed.
  • Zero sum bias: Belief that your situation is a zero sum situation and competing - even when there are unlimited resources.

We think we know what others think

We model the thinking of other people based on our own mind or a much simpler mind than ours.

  • Bystander effect: Individuals are less likely to offer help to a victim when there are other people present.
  • Curse of knowledge: When communicating with others, we assume that they have all the background information about the topic that we have already.
  • Extrinsic incentive error: We think other people are driven more by extrinsic motivators(like monetary reward) and we are driven more by intrinsic motivators(learning a new skill).
  • Illusion of asymmetric insight: Belief that we know other people better than the other person knows us.
  • Illusion of external agency: A belief that good/bad things happen to us because of external influences rather than personal actions.
  • Illusion of transparency: We think other people can understand our mental state fairly accurately.
  • Spotlight effect: We think we are noticed/thought about by others way more than we actually are.

Current mind state is projected to past and future

  • Declinism: Belief that a society or institution is becoming worse over time.
  • Impact bias: We **overestimate** duration and intensity of future emotional states.
  • Moral luck: Assigning praise or blame of an action based on outcome even if its not fully in their control.
  • Outcome bias: Evaluating the quality of a decision after the outcome is known.
  • Pessimism bias: We exaggerate the probability of bad things happening to us.
  • Hindsight Bias: People tend to think that events could have been easily predictable AFTER the outcome is clear.
  • Planning fallacy: We underestimate time required to finish a task.
  • Pro-innovation bias: If we see an innovation at work, we tend to believe that it can be applied everywhere without need of alterations.
  • Projection bias: We forecast our current preference on to a future event.
  • Restraint bias: We overestimate our ability to control impulsive behavior.
  • Rosy retrospection: We judge past events more positively than we do the present.
  • Self-consistency bias: We believe that we are consistent in our beliefs, behaviors, options, attitudes, etc.
  • Telescoping effect: Events in the past or future seems more distant(backward telescoping/time expansion) or nearer(forward telescoping) than they actually are.

3. We have to act fast

We evolved with the need to make quick decisions when faced with limited time and information. This programming continues in the present time in form of these thinking flaws.

To act, we should feel important and impactful

  • Barnum effect: We think that vauge and generic personality descriptions that can apply to a lot of people are very accurate and made specifically for them.
  • Defensive attribution hypothesis: We tend to believe theories about the cause of a mishap in a way that minimizes our own blame or threat in that mishap.
  • Dunning-Kruger Effect: Dunning–Kruger effect is a cognitive bias in which people with low ability at a task overestimate their ability.
  • Effort justification: If we put in a lot of effort into something, its value will go up in our mind.
  • Egocentric Bias: We overestimate our own perspective.
  • False consensus effect: We think our beliefs, behaviors, personal qualities are the norm.
  • Fundamental Attribution Error: We attribute the reason of our own(or of our friends) failures to the environment, but the failures of others(or our enemies) to their character.
  • Hard Easy Effect: Hard tasks makes you overconfident - and predict higher success probability while easier tasks makes you under confident - and predict lower success.
  • Illusion of control: We overestimate how much control we have over situations.
  • Illusory superiority: We overestimate our own qualities and abilities when compared to other people.
  • Optimism Bias: We exaggerate the probability of good things happening to us.
  • Overconfidence effect: We overestimate our performance, think our performance is better than that of others, and think we have more accurate beliefs.
  • Risk compensation: We adjust behavior according to perceived risk - we are more risk taking when we feel protected, and more careful when we sense greater risk.
  • Self serving bias: Our thinking and perception is distorted in ways to enhance our self esteem.
  • Social-desirability Bias: Survey respondents will give answers that be viewed favorably by others.
  • Third-person effect: We think that mass media affects other people more than it affects us.
  • Trait ascription bias: We think that our traits, attitudes, behaviors, moods are relatively variable(it can change as needed) - but other peoples traits are more predictable and static.

Favor immediate, known things over distant ones

We favor present over future. Stories about specific individuals over anonymous person.

  • Appeal to novelty: We believe that things are better just because they are new.
  • Hyperbolic discounting: We discount the value of a reward given later by a factor of the delay in getting the reward.
  • Identifiable victim effect: We are more willing to help a specific, identifiable person over a large but vaguely defined group with the same issue.

We want to finish things we have invested in

Helps us to finish things, even with difficult. Actions have inertia - once started its easier to continue.

  • Backfire effect: When we are presented with evidence against a pre-existing belief that we had, we sometimes reject the evidence and hold the belief even more strongly.
  • Disposition effect: When doing stock investing, we tend to sell off stocks that do well/increase in price - and keep the stock that is performing poorly.
  • Endowment effect: We want to keep a thing we own more than we want to get the same thing when we don't own it.
  • Generation effect: We remember things better if our own mind makes it up rather than when we just read it.
  • IKEA effect: We value things much higher if we created them(even partially).
  • Irrational escalation: When we get negative feedback for an outcome we are invested in, we increase effort towards it instead of altering course.
  • Pseudocertainty effect: We think of an outcome as certain - but in reality if we zoom out, it would be part of a multi-step process - which in entirety is not certain.
  • Sunk Cost Fallacy: People generally put in more investment into a failing thing to win back the investment that has already gone in.
  • Unit bias: We want to finish a unit of anything we are consuming - we don't want to stop in the middle.
  • Zero risk bias: We prefer to eliminate risks **completely** in a smaller part rather than reduce overall risk even if the second option reduces risk to a greater extend.

We want to have autonomy and status. Also, we want to avoid irreversable decisions

  • Abilene paradox: It is possible for a group to decide on something that is against most or all of the group members' preference.
  • Chesterton's fence: Ideally, we should not change something until we understand the purpose behind it.
  • Decoy effect: When deciding between two options, an unattractive third option can change the perceived preference between the other two.
  • Hippo Effect: Hippo - or Highest Paid Person's Opinion. In meetings, there might be a person who has the most experience or authority(usually the boss). Decisions they make might go unchallenged.
  • Law of the instrument: We tend to over-rely on a familiar tool.
  • Reactance: Reactance is the resistance we feel when there is a threat to our behavioral freedom.
  • Reverse psychology: Reverse psychology is a manipulation technique that asks someone to do something opposite to the action that is actually required.
  • Social comparison bias: We have a feeling of dislike and competitiveness towards people who we think are better than us.
  • Status quo bias: We prefer the current situation. We tend to think it is better than other alternatives.
  • System justification: We tend to defend the system we are in because it provides for many of our underlying needs.

We prefer simple or complete options over complex, ambiguous options

  • Ambiguity effect: We prefer options with known probability over options with unknown probability even if the payout is smaller in the known option.
  • Belief bias: We judge arguments based on the probability of the conclusion rather than how strongly the argument supports the conclusion.
  • Bike shed effect: We tend to spend more time on figuring out trivial things rather than spending time on the important things.
  • Conjunction fallacy: We think that specific conditions are more probable than a single general condition.
  • Delmore effect: We tend to have more defined and articulated goals about parts of our lives which has lower priority.
  • Information bias: We want to search for information even when it does not affect the decision.
  • Linguistic relativity: The languages you know influence your cognition and world view.
  • Occam's razor: The simplest explanation is often the best one.
  • Rhyme as reason effect: We believe that proverbs, sayings etc are more accurate if it rhymes.
  • Less-is-better effect: lesser option is preferred when evaluated separately.

4. What to remember

We have to prioritize what te remember and what to discard. We have a set of filters that will help us do this - but it can cause issues too.

We edit memories after the event

  • Broaden-and-build Theory: Negative emotions have immediate survival benefits. Positive emotions have long term benefits.
  • Cryptomnesia: We some times remember something that was forgotten - but we think that is an original thought that we made.
  • False memory: Memory error that can create slightly wrong or wildly inaccurate recollection that the person is very confident about.
  • Misattribution of memory: We tend to wrongly identify the source of a memory at point of recall.
  • Social identity theory: Social identity is the part of a person's self-concept that is made from their membership in a social group.
  • Spacing effect: Recollection of memory is better if we try to remember that information at specific intervals.
  • Suggestibility: Suggestibility is tendency to accept or act on the suggestion of others.

We discard specifics to create generalizations

  • Fading affect bias: Memories associated with negative emotions are forgotten more quickly than memories associated with positive emotions.
  • Implicit stereotype: We assign certain qualities to a member of an out group.
  • Prejudice: Prejudice is a preconceived(usually unfavorable) assignment of qualities to members of an out group.

We reduce events and lists to its key elements

We chose a few items to represent the whole.

  • Duration neglect: Our judgment of how unpleasant an experience is does not depend on the duration of the event - but on the peak(most intense part) and how quickly the pain reduces.
  • Leveling and sharpening: There are automatic functions of memory. Sharpening is when we remember small details in retelling of a memory. Leveling is when we leave out parts of the memory.
  • Memory inhibition: Memory inhibition is the ability **NOT** to remember irrelevant information.
  • Misinformation effect: Our memory can change and become less accurate based on information we get after the event.
  • Modality effect: Our memory of things we study is based on the presentations of the material.
  • Peak End Rule: We judge an experience based on what happens at either the peak(most intense part of the experience) or at the end of the event rather that the entire event.
  • Serial-position effect: We tend to recall the first(Primacy effect) and last items(Recency effect) in a series.
  • Serial recall: We are able to recollect items or events in the order they are given.
  • Suffix Effect: The [[Serial-position effect|Recency Effect]] ie. strong recall of last item of the list, will be impaired if there is an irrelevant item(that need not be remembered) at the end of the list.

We store memory differently based on how the experience was

Our brain will save things that it thinks is important. Importantce is judged based on the situation - not just the value of the information. Eg. Traumatic memories can be very strong.


I've stood on the sholders of gaints to create this site. Most of the heavy lifting was done by brilliant people before me...

  • Many Psycologists over the last few decades who did the original research.
  • All the wikipeda contributers for biases I have listed. Most of the source in the bias leads you to a wikipeda page.
  • Buster Benson for categorization and clustering.