15 cognitive biases

People are faced with a large amount of information, some of which are reliable, and some illuminate the area of ​​interest one-sidedly, and sometimes deliberately distorted.

This article is about how to distinguish reliable information from distorted information, and how to present information correctly to convince other people.

To begin with, people do not always think rationally. This is a given, which is due to the principles of our intellect, developed in the process of evolution. Conventionally, imagine a mind divided into two Systems. The structure of the mind is not so clear, but the simplification described will allow us to understand the causes of distortion. The first system generates solutions and hypotheses quickly "if we touch a hot object, we will pull our hand away." The second one makes decisions by logical reasoning. The first system generates hypotheses, and the second accepts or rejects them. This way of thinking is slow and energy intensive. Logical reasoning is less commonly used by people and requires a lot of effort. This is the cause of most cognitive biases.

So, the check mark “by default I agree” allowed to increase the number of donor consenters to 86% in Sweden, whereas in Denmark, where you need to consent yourself when obtaining rights, that is, to make an informed choice, the number of consent to donation is 4%.

Consider some of the cognitive biases:


Context forms the direction of thought. If the conversation is about food, recipes, taste, etc., then the word "m ... o" most people will continue as meat than as soap. Experiments show that if people are shown images or words associated with old age, people begin to walk more slowly. Money-minded people begin to act independently and selfishly, and are less likely to help others. This is due to the fact that the image gives rise to associations that form our behavior. The priming effect is used in branding. Call without hesitation the name of a fast food restaurant, or the most fashionable mobile phone.

The illusion of truth

The more recognizable the image, the more assertion is associated with security and truth. Thus, the frequent repetition of lies makes deceit believable. Truth is like a familiar sensation. Recognizable = ease. The more contrasting the color, the simpler the perception, the more plausible the statement. Simple words convince better than complex ones. Poems are perceived as information containing deep meaning. Font and rhythm of prose affect the feeling of credibility.

Cognitive stress mobilizes System 2. If you want people to start analyzing information, use poorly readable text, blurry pictures, etc.

Context sets credibility. Answer the question, "How many animals of each species with him on the ark did Moses take?" Most will answer 2, not noticing that Noah built the ark, and Moses is present in another biblical story. If you put Steve Jobs in the place of Moses, people will immediately notice the inconsistency.

Binding effect

The reference point affects our assessment. If you ask 2 questions to groups of people: “The height of the sequoia is greater or less than 365 meters, and what is the height, in your opinion?” and “The height of the sequoia is greater or less than 55 meters, and what is the height, in your opinion?” people will give differing grades. The numbers 365 and 55 are taken randomly. Those who have been given a snap of 365 will give an average of 257 meters, and those who have given a binding of 55 will answer 86 meters.

An example of a binding is the restriction of the offer "no more than X units of goods in one hand."

Retrospective distortion

People change their point of view with a shift to the perception of the past. If an event has occurred, a person overestimates the likelihood of his own forecast in the past and vice versa. The illusion of understanding the past gives rise to the illusion of a predicted future. People are perplexed as to how such an obvious mistake could be made, forgetting that at the time the decision was made, the mistake was not obvious.

Ignoring statistics and random events

People strive to find cause and effect relationships even where there is no connection. The sequence of events is endowed with a causal relationship. The illusion of skill, caused by the success of brokers in the stock market, is perceived as professionalism. When tossing a coin, the sequences O, O, O, O, P and O, P, O, P, P are equally probable, but it seems to people that the second sequence is more likely. “He had daughters 3 times, now a boy will be born” or “He has a light hand, Sergey has already scored 2 goals today, I will give him a pass to score the third.”

Regression to mean

The result consists of 2 factors: professionalism and luck. If the athlete performed very well, then with a great deal of confidence, we can say that he is a professional and the day was very successful, and vice versa. But the level of luck tends to the average with an increase in the number of attempts. In the following attempts, the likelihood that the athlete will perform worse than on a good day is greater, and vice versa. This explains the illusion of the effectiveness of punishment. It seems to people that punishment affects the improvement of the future result, although this is simply a regression to the average.

Distortion of probabilistic events

Rare events causing vivid images and associations attract more attention and people exaggerate the likelihood of their occurrence. Examples are air crashes, terrorist attacks, cataclysms, etc. The media play a role in invoking such images. People see less benefit in products that seem risky and are willing to overpay to minimize the risk of rare events. If a rare event does not cause vivid images, then it is ignored. A rare event must be “overloaded with details” so that we introduce it and give more weight.

People ignore a priori probability and judge by stereotype or reason. Man does not derive the particular from the general, but derives the general from the particular. An associative image prevails over statistics. Probability is harder to estimate than the value of "how much of."

Imagine a young man named Sergey. Sergey wears glasses, is an introvert, versed in technology and has Linux on his computer. Arrange the assumptions about Sergey in descending order: 1) Sergey designer 2) Sergey graduated from technical university and programmer 3) Sergey waiter 4) Sergey programmer. Points 2 and 4 are important here. Most will place answer 2 above 4, but this is a mistake. Programmers who graduate from a technical university make up only part of the programmers. Therefore, the probability that Sergey is simply a programmer is higher. People ignore a priori probability and choose a vivid description, since a vivid description is easier to imagine.

A common mistake is to manipulate small samples. As a result of the study, it was found that small schools prevail among high-performance schools. Casual explanations were found for this, and a large amount of money was invested in the creation of such schools. The mistake was that with a small sample (number of students), “abnormal situations” are more likely. All students are more likely to be smart or stupid. A similar picture exists among oncological diseases. Both the most healthy and the least healthy are residents of small towns, but this is due to the likelihood of an event on a small sample, and not clean air or hard work.

The significance of the unlikely events is exaggerated, while the highly probable ones are understated.

Psychologically, the transition 0–5% (the appearance of a chance) and 99–100% (the onset of certainty) are more significant than the transition 50–55%.

Distortion average scores. Better less and better.

If people are offered 2 service sets, where one consists only of items without defects, and the other of the same number of items without defects, to which objects with small defects are added, then most will appreciate a large set more expensive than a small one. But if you evaluate separately, people will appreciate a large service containing defects cheaper than a small one. This is due to the fact that people estimate the cost, not based on the principle of integrating the value of individual objects, but on the basis of the average cost of parts. So, a set of expensive pen + Chinese pen will be less valuable than just an expensive pen.

Reference point and loss effect

The unwillingness to lose is stronger than the desire to win. So, for games related to money, the coefficient of the ratio of gain from losses is 2. For health issues, the coefficient is 50, which shows sensitivity to losses. People are less likely to take risks to win and tend to take risks with inevitable losses. This is the basis of the business insurance model. Danger is more important than opportunity. Due to the difference in the price of losses, the poor are more likely to buy insurance from the rich, “negotiate” the price of concessions in negotiations, etc. A game with many attempts minimizes the effect of aversion to losses (it is easier to do business if it is known that there will be a second chance).

The expected value does not depend linearly with the increase in gain. This is described by a logarithmic scale. It is important not the quantitative state, but the degree of change. Growth from $ 1 to $ 10 million is emotionally more substantial than growth from $ 10 to $ 20 million, but is comparable to growth from $ 10 to $ 100 million.

The effect of ownership is that things intended for personal use and evoke an emotional response cause a greater sense of loss. How much are you ready to sell your favorite mug or tickets to a concert of your favorite band? But if the item was originally intended for sale or exchange, a feeling of loss does not arise. So, if a person is offered an equivalent choice, an additional salary or vacation, after the first choice, changing the position is more difficult, since there is a reference point and the change is perceived as loss plus gain, where the loss has more weight.

Error of irreparable losses - it is easier to continue investing in a unpromising business than to fix a loss.

Regret is stronger if caused as a result of action rather than inaction (Sergey sold dollars and bought rubles in June 1998 or Sergey did not buy dollars). The unusual situation increases regret (Sergey decided to give a ride to a fellow traveler, although he never did and was robbed).

Optimist mistake

Own experience is understandable. Because of this, a planning error occurs, people plan on the basis of available data, and not statistical facts. The mistake of opinion is that people consider themselves smarter than others. Neglect of competition is due to the effect of exclusivity. Due to the fact that their own experience is understandable, people tend to exaggerate their own contribution to the common cause. A useful technique for overcoming the optimist’s mistake is the “lifetime epicrisis” during which failure is presented and the reasons that led to it are analyzed.

Halo effect

People project an assessment of the known qualities of an object onto unknown qualities. A good speaker is perceived as a professional, a person who is pleasant in communication seems frank, etc. Thus, competence is associated with strength and reliability, and people with a pronounced chin and a slight smile are perceived as more competent. Properties are also projected onto surrounding objects, so in order to increase the rating of a politician, it is beneficial to meet with champions and prize winners and avoid debates with unpopular colleagues. The professionalism of the manager is evaluated by the financial performance of the company, although according to research, the correlation between leadership skills and success of the company is 0.3. Competent management guarantees success with a 60% probability.

Information Presentation Effect

An accuracy of 90% is perceived more positively than a 10% error statement.
The wording changes perception. Imagine 2 essentially identical statements of the question “will you agree to the game with a 10% probability of winning $ 95 and a 90% probability of losing 5” or “Will you pay $ 5 for a lottery where 10% of tickets win $ 100?”.

People are more likely to refuse a "discount for ..." than agree to a "surcharge for ...".

A kilometer per liter of gasoline distorts the consumption (the practice of counting in the USA). It is more correct to count in liters per kilometer.

A reminder that people are being watched makes them behave better.

People feel free from responsibility if they think others are aware of the situation.

Confidence in the statement falls with the number of arguments.

Better to "save 50%" than to "lose 50%" from the state.

Better "95% patient survival" than "5% patient mortality."

Neglecting and ranking importance

When deciding on importance, people ignore quantitative indicators. When conducting a charity campaign, raising money to save 100 tigers or 10,000 tigers will not affect the average amount of donations.

People tend to determine significance based on the location of the image within the category. Tigers occupy a high place of significance within the category of “animals”, and people suffering from migraines among other sick people occupy a low position of significance (although migraines spoil people's lives more often than other “significant”, but rare diseases). If a fundraising campaign is conducted for endangered tigers and people with migraines independently, the average donation for tigers will be higher. But if you put both of these proposals in one context, then donations for people will become higher, since the position of the category “people” is higher than the position of the category “animals”.

The effect of neglecting the denominator is that it is psychologically better to have 8 chances out of 100 than 1 out of 10. The risk of a child’s death of 0.001% is felt less worthy of attention than the death of ten out of a million children. A disease that kills 186 people out of 1,000 seems more dangerous than a disease that kills 24% of people and than kills 24 out of 100. The expression "insane people kill 1,000 people every year" has a greater effect than "the risk of death at the hands of an insane 0,00036%, which is comparable to the risk of death at the hands of a normal person. "

Substitution of Questions

Complex questions are replaced by simple ones. When people are asked "are you happy?", The person answers the question "what is my mood." “Will the company be successful?” replaced by "whether you like the technology, team, etc.". The response is affected by the priming effect if you ask “how many dates did you have?” And then “are you happy?” then the second question will be replaced by the first.

People tend to replace the general with the private.
The illusion of focus creates a distortion in favor of goods and attractive occupations at the beginning (car, phone) than occupations that take more time and experience (dancing). The focusing effect enhances the defamatory effort directed at the weak spot of the subject.

Ignoring Duration

Experiments have shown that people ignore the duration of exposure. In evaluating the pleasure or suffering received, only the peak value of the impact and sensation at completion plays a role. People’s score is the average between the sensations at the peak and the end.
The rule applies to impressions of stories heard, including stories of biographies. A short bright life is perceived better than a short bright life at the beginning and a less bright additional segment.


The article considers a number of examples of cognitive distortions due to the way we think. People in a state of fatigue, engaged in another matter, in high spirits, exhausted by self-control, or endowed with power, are at a greater risk of cognitive distortion. Therefore, if you are a boss who is tired at work, trying to impress partners and think about vacation, try to postpone fateful decisions until tomorrow!

You can familiarize yourself with this area, research, and approaches in detail by reading Daniel Kahneman's book “Think Slowly ... Decide Slowly”, which served as the basis for writing the article.