35+ Cognitive Biases That Shape the World Around You

This is a collection of the top 35 Cognitive Biases I’ve come across and put in my notes.

Keep these in mind as you navigate through your daily life and understand that other people are “falling victim” to these cognitive biases unknowingly. Cut them some slack – humans are flawed.

Being aware of when you’re up against a cognitive bias doesn’t fix the problem, but it is extremely helpful.

– J



Ambiguity effect – The tendency to avoid options for which missing information makes the probability seem “unknown.”


Availability cascade – A self-reinforcing process in which a collective belief gains more and more plausibility through its increasing repetition in public discourse (or “repeat something long enough and it will become true”).


Bandwagon effect – The tendency to do (or believe) things because many other people do (or believe) the same. Related to groupthink and herd behavior.


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.


Confirmation bias – The tendency to search for or interpret information in a way that confirms one’s preconceptions. (“You find what you want to see”)


Conjunction fallacy – The tendency to assume that specific conditions are more probable than general ones. (Remember your true audience, don’t tailor the user experience to a specific use case, always remember the broad audience is who you build for.)


Curse of knowledge – When better-informed people lose the ability to understand lesser-informed people.


Decoy effect – Preferences change when there is a third option that is asymmetrically dominated. (Fun tricks with pricing to be done here.)


Denomination effect – The tendency to spend more money when it is denominated in small amounts (e.g. coins) rather than large amounts (e.g. bills).


Endowment effect – The fact that people often demand much more to give up an object than they would be willing to pay to acquire it.


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


Gambler’s fallacy – The tendency to think that future probabilities are altered by past events, when in reality they are unchanged. Results from an erroneous conceptualization of the Law of large numbers. For example, “I’ve flipped heads with this coin five times consecutively, so the chance of tails coming out on the sixth flip is much greater than heads.”


Hindsight bias – Sometimes called the “I-knew-it-all-along” effect, the tendency to see past events as being predictable at the time those events happened. ( Sometimes phrased as “Hindsight is 20/20″)


Irrational escalation – The phenomenon where people justify increased investment in a decision, based on the cumulative prior investment, despite new evidence suggesting that the decision was probably wrong. (“Cut your losses”)


Loss aversion – The disutility of giving up an object is greater than the utility associated with acquiring it.


Mere exposure effect – The tendency to express undue liking for things merely because of familiarity with them.


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


Negativity bias – The tendency to pay more attention and give more weight to negative than positive experiences or other kinds of information.


Overconfidence effect – Excessive confidence in one’s own answers to questions. For example, for certain types of questions, answers that people rate as “99% certain” turn out to be wrong 40% of the time.


Planning fallacy – The tendency to underestimate task-completion times.


Post-purchase rationalization – The tendency to persuade oneself through rational argument that a purchase was a good value.


Pro-innovation bias – The tendency to reflect a personal bias towards an invention/innovation, while often failing to identify limitations and weaknesses or address the possibility of failure.


Reactance – The urge to do the opposite of what someone wants you to do out of a need to resist a perceived attempt to constrain your freedom of choice. (Reverse Psychology)


Restraint bias – The tendency to overestimate one’s ability to show restraint in the face of temptation.


Rhyme as reason effect – Rhyming statements are perceived as more truthful. (Marketing.)


Social comparison bias – The tendency, when making hiring decisions, to favor potential candidates who don’t compete with one’s own particular strengths.


Status quo bias – The tendency to like things to stay relatively the same (also called loss aversion, endowment effect, and system justification).


Zero-risk bias – Preference for reducing a small risk to zero over a greater reduction in a larger risk.


Actor-observer bias – the tendency for explanations of other individuals’ behaviors to overemphasize the influence of their personality and underemphasize the influence of their situation (see also Fundamental attribution error), and for explanations of one’s own behaviors to do the opposite (that is, to overemphasize the influence of our situation and underemphasize the influence of our own personality).


Dunning–Kruger effect – An effect in which incompetent people fail to realize they are incompetent because they lack the skill to distinguish between competence and incompetence.


Egocentric bias – Occurs when people claim more responsibility for themselves for the results of a joint action than an outside observer would.


Illusion of transparency – People overestimate others’ ability to know them, and they also overestimate their ability to know others.


Illusory superiority – Overestimating one’s desirable qualities, and underestimating undesirable qualities, relative to other people.


Ingroup bias – The tendency for people to give preferential treatment to others they perceive to be members of their own groups.


Self-serving bias – The tendency to claim more responsibility for successes than failures. It may also manifest itself as a tendency for people to evaluate ambiguous information in a way beneficial to their interests


System justification – The tendency to defend and bolster the status quo. Existing social, economic, and political arrangements tend to be preferred, and alternatives disparaged sometimes even at the expense of individual and collective self-interest.


– J