[2020] Ultimate List of Cognitive Biases with examples (Part 1 of 4)

Section One

Section Two

Section Three

Section Four

Section One

Too much info

There is just too much information in the world, we have no choice but to filter almost all of it out. Our brain uses a few simple tricks to pick out the bits of information that are most likely going to be useful in some way.

Chapter One

We notice things already primed in memory or repeated often

This is the simple rule that our brains are more likely to notice things that are related to stuff that’s recently been loaded in memory.

Availability heuristic

The tendency to overestimate the likelihood of events with greater “availability” in memory, which can be influenced by how recent the memories are or how unusual or emotionally charged they may be.

For a more in-depth understanding of the availability heuristic check out this article by kent hendricks.

Example – After seeing news stories about child abductions, people may judge that the likelihood of this event is greater.

This amazing illustration of the conjunction fallacy was made by @cartoonbias. Do check out their work on Instagram.

Attentional bias

The tendency of perception to be affected by recurring thoughts.

Example – Drug addiction is an example of attentional bias in that certain memories or objects can prompt intense cravings to one’s drug of choice.

This amazing illustration of the conjunction fallacy was made by @cartoonbias. Do check out their work on Instagram.

Illusory truth effect

A tendency to believe that a statement is true if it is easier to process, or if it has been stated multiple times, regardless of its actual veracity. These are specific cases of truthiness.

Example – During election campaigns, false information about a candidate, if repeated in TV commercials, can cause the public to believe it.

This amazing illustration of the conjunction fallacy was made by @cartoonbias. Do check out their work on Instagram.

Mere-exposure effect

The tendency to express undue liking for things merely because of familiarity with them.

Example – College-age students were asked to read an article on the computer while banner ads flashed at the top of the screen. The results showed that each group exposed to the “test” banner rated the ad more favorably than other ads shown less frequently or not at all.

Context effect

That cognition and memory are dependent on context, such that out-of-context memories are more difficult to retrieve than in-context memories (e.g., recall time and accuracy for a work-related memory will be lower at home, and vice versa).

Example – In “THE CAT” H and A could be written with the same symbol. Yet we have little trouble reading them as “H” and “A” in their appropriate contexts.

Cue-dependent forgetting

Cue-dependent forgetting, or retrieval failure, is the failure to recall information without memory cues.

Example – If John tries and fails to recollect the memories he had about a vacation he went on, and someone else mentions the fact that he rented a classic car during this vacation, this may make John remember all sorts of things from that trip, such as what he ate there, where he went and what books he read.

Mood-congruent memory bias

The improved recall of information congruent with one’s current mood.

Example – For a person who has only had positive interactions with the word ‘dog’, the person would subsequently connect to the emotional nodes that represented positive meanings such as dog = pet = happiness in childhood.

Frequency illusion 

The illusion in which a word, a name, or other thing that has recently come to one’s attention suddenly seems to appear with improbable frequency shortly afterwards (not to be confused with the recency illusion or selection bias). Also called Baader-Meinhof phenomenon.

Example – If someone close to a person dies that person may imagine the face or bodyshape of the recently deceased on people walking by.

Empathy gap

The tendency to underestimate the influence or strength of feelings, in either oneself or others.

Example – An inability to minimize one’s gap in empathy can lead to negative outcomes in medical settings (e.g., when a doctor needs to accurately diagnose the physical pain of a patient), and in workplace settings (e.g., when an employer needs to assess the need for an employee’s bereavement leave).

Omission bias

The tendency to judge harmful actions (commissions) as worse, or less moral, than equally harmful inactions (omissions).

Example – NBA statistics showcased referees called 50 percent fewer fouls in the final moments of close games.

Base rate fallacy

The tendency to ignore base rate information (generic, general information) and focus on specific information (information only pertaining to a certain case).

Example – Imagine running an infectious disease test on a population A of 1000 persons, in which 2% are infected. The test has a false positive rate of 5% (0.05) and no false negative rate. Only 20 of the 69 total people with a positive test result are actually infected.

Interoceptive bias

The tendency for sensory input about the body itself to affect one’s judgement about external, unrelated circumstances.

Example – Parole judges are more lenient when fed and rested. Their instincts for getting food activate. Which means that they whole body and thinking are now partly controlled by this mood.

Chapter Two

Bizarre, funny, visually striking, or anthropomorphic things stick out more than non-bizarre/unfunny things

Our brains tend to boost the importance of things that are unusual or surprising. Alternatively, we tend to skip over information that we think is ordinary or expected.

Bizarreness effect

Bizarre material is better remembered than common material.

Example – “Do ya see that pier out there on the lake? I built that pier with my own bare hands, driving each piling deep into ground so that it would last a lifetime. Do they call me McGreggor the pier builder? No. But ya fuck one goat.”

Humor effect

That humorous items are more easily remembered than non-humorous ones, which might be explained by the distinctiveness of humor, the increased cognitive processing time to understand the humor, or the emotional arousal caused by the humor.

Example – A funny scene from a movie may be brought up in a review as a memorable scene. Humor has a bizarreness effect as the punchline is often something unexpected that breaks the current thinking and mood.

Von Restorff effect

That an item that sticks out is more likely to be remembered than other items.

Example – If a person examines a shopping list with one item highlighted in bright green, he or she will be more likely to remember the highlighted item than any of the others. Additionally, in the following list of words – desk, chair, bed, table, chipmunk, dresser, stool, couch – chipmunk will be remembered the most as it stands out against the other words in its meaning.

Picture superiority effect

The notion that concepts that are learned by viewing pictures are more easily and frequently recalled than are concepts that are learned by viewing their written word form counterparts.

Example – This effect has been shown to occur in recognition memory tasks, where items studied as pictures are better remembered than items studied as words, even when targets are presented as words during the test phase.

Self-relevance effect

That memories relating to the self are better recalled than similar information relating to others.

Example – Older adults exhibit increased recall when using self-generated strategies that rely on personally relevant information (e.g., important birthdates) relative to other mnemonic strategies.


A cognitive process in which people have a difficult time making a decision when faced with many options.

Example – When USSR collapsed and introduced a more capitalist system people had a harder time picking goods in stores as now they went from having 1 soda option to 20.

Salience bias

The tendency to focus on items that are more prominent or emotionally striking and ignore those that are unremarkable, even though this difference is often irrelevant by objective standards.

Example – The bizarreness effect, but based on things that overall stand out.

“Thus, vivid and easily imagined causes of death (for example, tornadoes) often receive inflated estimates of probability, and less-vivid causes (for example, asthma attacks) receive low estimates, even if they occur with a far greater frequency (here, by a factor of twenty).” – Richard H. Thaler

Exaggerated expectation 

The tendency to expect or predict more extreme outcomes than those outcomes that actually happen.

Example – We imagine scenarios that are exaggerated to make sure we are prepared for anything. Similar to loss aversion.

Chapter Three

We notice when something has changed

And we’ll generally tend to weigh the significance of the new value by the direction the change happened (positive or negative) more than re-evaluating the new value as if it had been presented alone. Also applies to when we compare two similar things.


The tendency to rely too heavily, or “anchor”, on one trait or piece of information when making decisions (usually the first piece of information acquired on that subject).

Read more about anchoring here.

Example – The initial price offered for a used car, set either before or at the start of negotiations, sets an arbitrary focal point for all following discussions. Prices discussed in negotiations that are lower than the anchor may seem reasonable, perhaps even cheap to the buyer, even if said prices are still relatively higher than the actual market value of the car.


Conservatism or conservatism refers to the tendency to revise one’s belief insufficiently when presented with new evidence.

Example – “There are two bookbags, one containing 700 red and 300 blue chips, the other containing 300 red and 700 blue. Take one of the bags. Now, you sample, randomly, with replacement after each chip. In 12 samples, you get 8 reds and 4 blues. what is the probability that this is the predominantly red bag?”

Most subjects chose an answer around .7. The correct answer according to Bayes’ theorem is closer to .97.

Contrast effect

The enhancement or reduction of a certain stimulus’ perception when compared with a recently observed, contrasting object.

Example – Cognition example: A person will appear more or less attractive than that person does in isolation when immediately preceded by, or simultaneously compared to, respectively, a less or more attractive person.

Distinction bias

The tendency to view two options as more dissimilar when evaluating them simultaneously than when evaluating them separately.

Example – When televisions are displayed next to each other on the sales floor, the difference in quality between two very similar, high-quality televisions may appear great. A consumer may pay a much higher price for the higher-quality television, even though the difference in quality is imperceptible when the televisions are viewed in isolation.

Focusing effect

The tendency to place too much importance on one aspect of an event.

Example – Similar to anchoring.

Although negotiators can generally appraise an offer based on multiple characteristics, studies have shown that they tend to focus on only one aspect. In this way, a deliberate starting point can strongly affect the range of possible counteroffers.

Framing effect

Drawing different conclusions from the same information, depending on how that information is presented.

Read more about framing here.

Example – Treatment A was chosen by 72% of participants when it was presented with positive framing (“saves 200 lives”) dropping to 22% when the same choice was presented with negative framing (“400 people will die”).

This amazing illustration of the conjunction fallacy was made by @cartoonbias. Do check out their work on Instagram.

Money illusion 

The tendency to concentrate on the nominal value (face value) of money rather than its value in terms of purchasing power.

Example – Experiments have shown that people generally perceive an approximate 2% cut in nominal income with no change in monetary value as unfair, but see a 2% rise in nominal income where there is 4% inflation as fair, despite them being almost rational equivalents.

Weber-Fechner law

Difficulty in comparing small differences in large quantities.

Example – Psychological studies show that it becomes increasingly difficult to discriminate between two numbers as the difference between them decreases. This is called the distance effect.

Conservatism or Regressive bias

Tendency to remember high values and high likelihoods/probabilities/frequencies as lower than they actually were and low ones as higher than they actually were. Based on the evidence, memories are not extreme enough.

Example – Memory variant of conservatism. Probably should be seen as the same bias.

Chapter Four

We are drawn to details that confirm our own existing beliefs

This is a big one. As is the corollary: we tend to ignore details that contradicts our own beliefs.

Confirmation bias

The tendency to search for, interpret, focus on and remember information in a way that confirms one’s preconceptions.

Example – Probably the most well-known bias.

Experiments have found repeatedly that people tend to test hypotheses in a one-sided way, by searching for evidence consistent with their current hypothesis. The ebay marketing department spent millions on Google search advertisements and to prove that they made ebay a profit they just did a simple ads vs. sale figures correlation. But when scientists shut down these ads in some USA states it became clear that the ads were ineffectual and actually lost the company a great deal of money.

This amazing illustration of the conjunction fallacy was made by @cartoonbias. Do check out their work on Instagram.

Congruence bias

The tendency to test hypotheses exclusively through direct testing, instead of testing possible alternative hypotheses.

Example – Peter Wason gave subjects the number sequence “2, 4, 6”, telling the subjects that this sequence followed a particular rule and instructing subjects to find the rule underlying the sequence logic. Most subjects just thought it was “increasing by 2” and only tested for that and not alternative, but maybe more simple rules like “equal numbers”.

Post-purchase rationalization 

Choice-supportive bias or post-purchase rationalization is the tendency to retroactively ascribe positive attributes to an option one has selected and/or to demote the forgone options.

Example – We tend to like the item we selected from 2 items no matter which one we selected.

Choice-supportive bias

The tendency to remember one’s choices as better than they actually were.

Example – The Deese-Roediger-McDermott paradigm (DRM) consists of a participant listening to an experimenter read lists of thematically related words (e.g. table, couch, lamp, desk); then after some period of time the experimenter will ask if a word was presented in the list. Participants often report that related but non-presented words (e.g. chair) were included in the encoding series, essentially suggesting that they ‘heard’ the experimenter say these non-presented words (or critical lures). Incorrect ‘yes’ responses to critical lures, often referred to as false memories, are remarkably high under standard DRM conditions.

Selective perception 

The tendency for expectations to affect perception.

Example – Studies have shown that students who were told they were consuming alcoholic beverages (which in fact were non-alcoholic) perceived themselves as being “drunk”, exhibited fewer physiological symptoms of social stress, and drove a simulated car similarly to other subjects who had actually consumed alcohol. The result is somewhat similar to the placebo effect.

Observer-expectancy effect

When a researcher expects a given result and therefore unconsciously manipulates an experiment or misinterprets data in order to find it (see also subject-expectancy effect).

Example – The classic example of experimenter bias is that of “Clever Hans”, an Orlov Trotter horse claimed by his owner von Osten to be able to do arithmetic and other tasks. Hans answered correctly 89% of the time. However, when von Osten did not know the answers, Hans answered only 6% correctly.

Ostrich effect

Ignoring an obvious (negative) situation.

Example – In one experiment people in Scandinavia looked up the value of their investments 50% to 80% less often during bad markets.

This amazing illustration of the conjunction fallacy was made by @cartoonbias. Do check out their work on Instagram.

Subjective validation 

Perception that something is true if a subject’s belief demands it to be true. Also assigns perceived connections between coincidences.

Example – More specified confirmation bias.

If someone enjoys eating bacon and they were to come across an article that talks about how healthy bacon is for you, they will tend to believe it more because this “validates” eating more bacon.

Continued influence effect

The tendency to believe previously learned misinformation even after it has been corrected. Misinformation can still influence inferences one generates after a correction has occurred. Similar to Backfire effect.

Example – To defend their president and the attack on Iraq some conservatives said things like: “Immediately before the U.S. invasion, Iraq had an active weapons of mass destruction program, the ability to produce these weapons, and large stockpiles of WMD, but Saddam Hussein was able to hide or destroy these weapons right before U.S. forces arrived.”

Semmelweis reflex

The tendency to reject new evidence that contradicts a paradigm.

Example – The term derives from the name of a Hungarian physician, lgnaz Semmelweis, who in 1847 discovered that childbed fever mortality rates fell ten-fold when doctors disinfected their hands with a chlorine solution before moving from one patient to anotherUor, most particularly, after an autopsy. Despite the overwhelming empirical evidence, his fellow doctors rejected his hand-washing suggestions, often for non-medical reasons. For instance, some doctors refused to believe that a gentleman’s hands could transmit disease.

Overjustification effect

The overjustification effect occurs when an expected external incentive such as money or prizes decreases a person’s intrinsic motivation to perform a task. Overjustification is an explanation for the phenomenon known as motivational “crowding out.”

Example – Empirical evidence shows that expected financial rewards “crowd out intrinsic motivation, while the size of the monetary reward simultaneously provides extrinsic motivation. If the size of the monetary reward is not large enough to compensate for the loss of intrinsic motivation, overall engagement can decline.

False uniqueness bias

The tendency of people to see their projects and themselves as more singular than they actually are.

Example – The Wiki page for this bias is barely 2 lines long.

Default effect

When given a choice between several options, the tendency to favor the default one.

Example – Setting or changing defaults has been proposed as an effective way of influencing behavior. For example, with respect to deciding whether to become an organ donor, giving consent to receive e-mail marketing, choosing car insurance plans, choosing which food to eat, selecting which car options to purchase, choosing between different energy providers, or choosing the level of one’s retirement contributions. Setting defaults are an important example of nudges or soft paternalist policies.

Chapter Five

We notice flaws in others more easily than we notice flaws in ourselves

Yes, before you see this entire article as a list of quirks that compromise how other people think, realize that you are also subject to these biases.

Bias blind spot

The tendency to see oneself as less biased than other people, or to be able to identify more cognitive biases in others than in oneself.

Example – Experimenters explained cognitive bias, and asked the subjects how it might have affected their judgment. The subjects rated themselves as less susceptible to bias than others in the experiment (confirming the bias blind spot). When they had to explain their judgments, they used different strategies for assessing their own and others’ bias.

This amazing illustration of the conjunction fallacy was made by @cartoonbias. Do check out their work on Instagram.

Naïve cynicism 

Expecting more egocentric bias in others than in oneself.

Example – “I have had a philosophy for some time in regard to SALT, and it goes like this: the Russians will not accept a SALT treaty that is not in their best interest, and it seems to me that if it is their best interests, it can’t be in our best interest.”

Naïve realism 

The belief that we see reality as it really is U objectively and without bias; that the facts are plain for all to see; that rational people will agree with us; and that those who don’t are either uninformed, lazy, irrational, or biased.

Example – Though they looked at the same footage, fans from both schools perceived the game very differently. The Princeton students “saw” the Dartmouth team make twice as many infractions as their own team, and they also saw the team make twice as many infractions compared to what the Dartmouth students saw.

Next Section

Ultimate List of Cognitive Biases with examples (Part 2 of 4) – Not enough meaning