In psychology and cognitive science, a memory bias is a cognitive bias that either enhances or impairs the recall of a memory (either the chances that the memory will be recalled at all, or the amount of time it takes for it to be recalled, or both), or that alters the content of a reported memory. There are many types of memory bias, including:

Name Description
Bizarreness effect Bizarre material is better remembered than common material.
Choice-supportive bias In a self-justifying manner retroactively ascribing one’s choices to be more informed than they were when they were made.
Change bias After an investment of effort in producing change, remembering one’s past performance as more difficult than it actually was.
Childhood amnesia The retention of few memories from before the age of four.
Conservatism or Regressive bias Tendency to remember high values and high likelihoods/probabilities/frequencies as lower than they actually were and low ones as higher than they actually were. Based on the evidence, memories are not extreme enough.
Consistency bias Incorrectly remembering one’s past attitudes and behaviour as resembling present attitudes and behaviour.
Context effect That cognition and memory are dependent on context, such that out-of-context memories are more difficult to retrieve than in-context memories (e.g., recall time and accuracy for a work-related memory will be lower at home, and vice versa)
Cross-race effect The tendency for people of one race to have difficulty identifying members of a race other than their own.
Cryptomnesia A form of misattribution where a memory is mistaken for imagination, because there is no subjective experience of it being a memory.
Egocentric bias Recalling the past in a self-serving manner, e.g., remembering one’s exam grades as being better than they were, or remembering a caught fish as bigger than it really was.
Fading affect bias A bias in which the emotion associated with unpleasant memories fades more quickly than the emotion associated with positive events.
False memory A form of misattribution where imagination is mistaken for a memory.
Generation effect (Self-generation effect) That self-generated information is remembered best. For instance, people are better able to recall memories of statements that they have generated than similar statements generated by others.
Google effect The tendency to forget information that can be found readily online by using Internet search engines.
Hindsight bias The inclination to see past events as being more predictable than they actually were; also called the “I-knew-it-all-along” effect.
Humor effect That humorous items are more easily remembered than non-humorous ones, which might be explained by the distinctiveness of humor, the increased cognitive processing time to understand the humor, or the emotional arousal caused by the humor.
Illusion of truth effect That people are more likely to identify as true statements those they have previously heard (even if they cannot consciously remember having heard them), regardless of the actual validity of the statement. In other words, a person is more likely to believe a familiar statement than an unfamiliar one.
Illusory correlation Inaccurately remembering a relationship between two events.
Lag effect See spacing effect.
Leveling and Sharpening Memory distortions introduced by the loss of details in a recollection over time, often concurrent with sharpening or selective recollection of certain details that take on exaggerated significance in relation to the details or aspects of the experience lost through leveling. Both biases may be reinforced over time, and by repeated recollection or re-telling of a memory.
Levels-of-processing effect That different methods of encoding information into memory have different levels of effectiveness.
List-length effect A smaller percentage of items are remembered in a longer list, but as the length of the list increases, the absolute number of items remembered increases as well.
Misinformation effect Memory becoming less accurate because of interference from post-event information.
Modality effect That memory recall is higher for the last items of a list when the list items were received via speech than when they were received through writing.
Mood-congruent memory bias The improved recall of information congruent with one’s current mood.
Next-in-line effect That a person in a group has diminished recall for the words of others who spoke immediately before himself, if they take turns speaking.
Part-list cueing effect That being shown some items from a list and later retrieving one item causes it to become harder to retrieve the other items.
Peak–end rule That people seem to perceive not the sum of an experience but the average of how it was at its peak (e.g. pleasant or unpleasant) and how it ended.
Persistence The unwanted recurrence of memories of a traumatic event.
Picture superiority effect The notion that concepts that are learned by viewing pictures are more easily and frequently recalled than are concepts that are learned by viewing their written word form counterparts.
Positivity effect That older adults favor positive over negative information in their memories.
Primacy effect, Recency effect & Serial position effect That items near the end of a sequence are the easiest to recall, followed by the items at the beginning of a sequence; items in the middle are the least likely to be remembered.
Processing difficulty effect That information that takes longer to read and is thought about more (processed with more difficulty) is more easily remembered.
Reminiscence bump The recalling of more personal events from adolescence and early adulthood than personal events from other lifetime periods.
Rosy retrospection The remembering of the past as having been better than it really was.
Self-relevance effect That memories relating to the self are better recalled than similar information relating to others.
Source confusion Confusing episodic memories with other information, creating distorted memories.
Spacing effect That information is better recalled if exposure to it is repeated over a long span of time rather than a short one.
Spotlight effect The tendency to overestimate the amount that other people notice your appearance or behavior.
Stereotypical bias Memory distorted towards stereotypes (e.g., racial or gender), e.g., “black-sounding” names being misremembered as names of criminals.
Suffix effect Diminishment of the recency effect because a sound item is appended to the list that the subject is not required to recall.
Suggestibility A form of misattribution where ideas suggested by a questioner are mistaken for memory.
Telescoping effect The tendency to displace recent events backward in time and remote events forward in time, so that recent events appear more remote, and remote events, more recent.
Testing effect The fact that you more easily remember information you have read by rewriting it instead of rereading it.
Tip of the tongue phenomenon When a subject is able to recall parts of an item, or related information, but is frustratingly unable to recall the whole item. This is thought an instance of “blocking” where multiple similar memories are being recalled and interfere with each other.
Verbatim effect That the “gist” of what someone has said is better remembered than the verbatim wording. This is because memories are representations, not exact copies.
Von Restorff effect That an item that sticks out is more likely to be remembered than other items.
Zeigarnik effect That uncompleted or interrupted tasks are remembered better than completed ones.


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