Important cognitive biases

Social Cognition Biases

Correspondence Bias: The tendency to infer that people's behavior corresponds to their disposition (personality). Actor/Observer Difference: The tendency to see other people's behavior as dispositionally caused but focusing more on the role of situational factors when explaining one's own behavior. Self-Serving Attributions: Explanations for one's successes that credit internal, dispositional factors and explanations for one's failures that blame external, situational factors. Belief in a Just World: The assumption that bad things happen to bad people and good things happen to good people. Own-Race Bias: The fact that people are better at recognizing faces of their own race than those of other races. Ultimate Attribution Error: The tendency to make dispositional attributions about an entire group of people. In-group bias: The tendency to reserve positive feelings and special treatment to people we have defined as being part of our in-group (the group with which a person identifies and of which he or she feels a member), and negative feelings and unfair treatment to people we have defined as being part of our out-group (groups which an individual does not identify with). Out-group homogeneity bias: The perception that those in the out-group are more similar (homogenous) to each other than they really are, as well as more similar than the members of the in-group are (i.e., the belief that “they’re all alike”). Illusory Correlation: The tendency to see relationships, or correlations, between events that are actually unrelated; this is one way stereotypes form and endure. False Consensus Effect: The tendency for people to overestimate the extent to which others agree with them.

Reasoning Biases

Representativeness Heuristic: The tendency for people to use similarity or representativeness as a proxy for probabilistic thinking; this can lead to base-rate neglect, the tendency for people to insufficiently take into account the overall frequency (base rate) of an event in a population. Hindsight Bias: The tendency for people to exaggerate how much they could have predicted an outcome after knowing that it occurred. Projection Bias: The tendency for people to exaggerate the degree to which their future tastes will resemble their current tastes. Impact Bias: The tendency to overestimate the intensity and duration of our emotional reactions to future negative events. Conjunction Fallacy: The tendency to assume that specific conditions are more probable than general ones. Gambler's Fallacy: The false belief that in a sequence of independent draws from a distribution, an outcome that has not occurred for a while is more likely to come up on the next draw. Hot-Hand Fallacy: The false or exaggerated belief that a person's performance varies systematically over the short run. Availability Heuristic: The tendency for people to assess the frequency of a class or the probability of an event by the ease with which instances or occurrences can be brought to mind. Anchoring and Adjustment Heuristic: The tendency for people to answer a question by starting at some first-pass guess based on memory or the environment, and adjust that guess until they are satisfied with the answer. Curse of Knowledge: If you know something, you can't appreciate what it's like not to know it.

Memory Biases: The serial position effect refers to the finding that recall accuracy varies as a function of an item's position within a study list. Primacy Effect: the tendency to weigh initial events more than subsequent events. People tend to recall items that were at the beginning of a list rather than items that were in the middle of a list. [[Recency Effect]: the tendency to weigh recent events more than earlier events. People tend to recall items that were at the end of a list rather than items that were in the middle of a list.|Recency Effect]: the tendency to weigh recent events more than earlier events. People tend to recall items that were at the end of a list rather than items that were in the middle of a list.]]

Source: http://www.quora.com/Psychology/What-are-the-most-important-cognitive-biases-to-be-aware-of