One of the aspects of investing that I have long enjoyed is looking at the many ways are wetware works against us. Despite what nearly half of America believes, we have evolved in a certain way, and that has significant repercussions for our analytical processes.
There are many ways our brain wiring fools us. I discussed a few in the Apprenticed Investor series — Know Thyself and Curb Your Enthusiasm — that are worth revisiting. And one of the favored books around here is Thomas Gilovich: How We Know What Isn’t So.
Many of the common foibles investors get themselves into can be tracked to our propensity for cognitive bias. What our minds commonly do to distort our own view of reality has an impact on our invement results.
So you can imagine my surprise and delight when I stumbled upon this Wikipedia list. Here are the 26 most studied and widely accepted cognitive biases:
- Bandwagon effect – the tendency to do (or believe) things because many other people do (or believe) the same. Related to groupthink, herd behaviour, and manias. Carl Jung pioneered the idea of the collective unconscious which is considered by Jungian psychologists to be responsible for this cognitive bias.
- Bias blind spot – the tendency not to compensate for one’s own cognitive biases.
- Choice-supportive bias – the tendency to remember one’s choices as better than they actually were.
- Confirmation bias – the tendency to search for or interpret information in a way that confirms one’s preconceptions.
- Congruence bias – the tendency to test hypotheses exclusively through direct testing.
- Contrast effect – the enhancement or diminishment of a weight or other measurement when compared with recently observed contrasting object.
- Déformation professionnelle – the tendency to look at things according to the conventions of one’s own profession, forgetting any broader point of view.
- Disconfirmation bias – the tendency for people to extend critical scrutiny to information which contradicts their prior beliefs and uncritically accept information that is congruent with their prior beliefs.
- Endowment effect – the tendency for people to value something more as soon as they own it.
- Focusing effect – prediction bias occurring when people place too much importance on one aspect of an event; causes error in accurately predicting the utility of a future outcome.
- Hyperbolic discounting – the tendency for people to have a stronger preference for more immediate payoffs relative to later payoffs, the closer to the present both payoffs are.
- Illusion of control – the tendency for human beings to believe they can control or at least influence outcomes which they clearly cannot.
- Impact bias – the tendency for people to overestimate the length or the intensity of the impact of future feeling states.
- Information bias – the tendency to seek information even when it cannot affect action.
- Loss aversion – the tendency for people to strongly prefer avoiding losses over acquiring gains (see also sunk cost effects)
- Neglect of probability – the tendency to completely disregard probability when making a decision under uncertainty.
- Mere exposure effect – the tendency for people to express undue liking for things merely because they are familiar with them.
- Omission bias – The tendency to judge harmful actions as worse, or less moral, than equally harmful omissions (inactions).
- Outcome bias – the tendency to judge a decision by its eventual outcome instead of based on the quality of the decision at the time it was made.
- 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.
- Pseudocertainty effect – the tendency to make risk-averse choices if the expected outcome is positive, but make risk-seeking choices to avoid negative outcomes.
- Selective perception – the tendency for expectations to affect perception.
- Status quo bias – the tendency for people to like things to stay relatively the same.
- Von Restorff effect – the tendency for an item that “stands out like a sore thumb” to be more likely to be remembered than other items.
- Zero-risk bias – preference for reducing a small risk to zero over a greater reduction in a larger risk.
Complete list of cognitive biases – Wikipedia