Cognitive bias

A cognitive bias is any of a wide range of observer effects identified in cognitive science and social psychology including very basic statistical, social attribution, and memory errors that are common to all human beings. Biases drastically skew the reliability of anecdotal and legal evidence. Social biases, usually called attributional biases affect our everyday social interactions. And biases related to probability and decision making significantly affect the scientific method which is deliberately designed to minimize such bias from any one observer.

Overview
Bias arises from various life, loyalty and local risk and attention concerns that are difficult to separate or codify. They were first identified by Amos Tversky and Daniel Kahneman as a foundation of behavioral economics. Tversky and Kahneman claim that they are at least partially the result of problem-solving using heuristics, including the availability heuristic and the representativeness heuristic.

Recently, some scientists (David Funder and Joachim Krueger) have raised doubt as to whether all of the 'biases' are in fact errors. Their theories hold that some so called 'biases' may in fact be 'approximation shortcuts', that aid humans in making predictions when information is in short supply. For example, the false consensus effect may be viewed as a reasonable estimation based on a single known data point, your own opinion, instead of a false belief that other people agree with you.

Types of cognitive biases
The following is a list of the more commonly studied cognitive biases
 * Hindsight bias sometimes called the "I-knew-it-all-along" effect, is the inclination to see past events as being predictable
 * Fundamental attribution error the tendency for people to over-emphasize personality-based explanations for behaviors observed in others while under-emphasizing the role and power of situational influences on the same behavior.
 * Confirmation bias the tendency to search for or interpret information in a way that confirms one's preconceptions.
 * 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.

There are of course several other cognitive biases, as people keep imagining more all the time. In fact, one might imagine that there is a cognitive bias that is a tendency to invent more cognitive biases. See the list of cognitive biases.