People with only a little knowledge of a subject tend to overestimate their skill, because the same knowledge they lack is what they would need to judge their own performance. As learning deepens, confidence collapses before slowly rebuilding on more honest footing. (The familiar “confidence curve” is a popular simplification of the original 1999 findings, but it captures the felt experience well.)
Overthinking a decision until no decision gets made. When every option is weighed against every possible outcome, the cost of choosing wrongly looms larger than the cost of not choosing at all, and the person stalls.
The tendency to return to a stable baseline of happiness after good or bad events. A raise, a new home or a prize feels wonderful at first, then becomes the new normal, and the desire for the next thing begins again.
The mental discomfort of holding two conflicting beliefs, or of acting against one’s own values. Leon Festinger described how people relieve the tension, often by changing a belief, adding a justification or avoiding the evidence, rather than facing the contradiction.
A situation in which most people privately doubt or reject a norm but assume everyone else accepts it, so no one speaks up. A classroom full of confused students who each think they are the only one is the textbook example.
The tendency to overestimate how much other people notice our appearance and mistakes. In a well-known study by Thomas Gilovich and colleagues, students made to wear an embarrassing T-shirt guessed that about twice as many people noticed it as actually did.
When recalling a list, people remember the first items (the primacy effect) and the last items (the recency effect) far better than the ones in the middle. Early items get rehearsed into long-term memory, and the latest are still fresh in short-term memory.
A temporary or permanent dissolution of the sense of a separate, fixed self. It is reported in deep meditation, in psychedelic experiences and in times of profound crisis, and is often described as terrifying and freeing in the same moment.
A persistent feeling of being a fraud despite evidence of real competence. People with it tend to credit their success to luck or timing, and live in fear of being “found out.”
Unwanted, involuntary thoughts or images that pop into the mind, often disturbing and out of character. They are extremely common. They become distressing when a person treats them as meaningful or tries hard to suppress them, which tends to make them return more often, as in obsessive-compulsive disorder.
Black-and-white thinking about oneself or other people, where someone is all good or all bad with nothing in between. It is a defence mechanism described in psychoanalytic theory and is especially associated with borderline personality disorder, where it can swing rapidly from idealising to devaluing.