Memory Errors
Memories are fallible. They are reconstructions of reality filtered through people's minds, not perfect snapshots of events. Because memories are reconstructed, they are susceptible to being manipulated with false information. Memory errors occur when memories are recalled incorrectly; a memory gap is the complete loss of a memory.
Schemas
In a 1932 study, Frederic Bartlett demonstrated how telling and retelling a story distorted information recall. He told participants a complicated Native American story and had them repeat it over a series of intervals. With each repetition, the stories were altered. Even when participants recalled accurate information, they filled in gaps with false information. Bartlett attributed this tendency to the use of schemas. A schema is a generalization formed in the mind based on experience. People tend to place past events into existing representations of the world to make memories more coherent. Instead of remembering precise details about commonplace occurrences, people use schemas to create frameworks for typical experiences, which shape their expectations and memories. The common use of schemas suggests that memories are not identical reproductions of experience, but a combination of actual events and already-existing schemas. Likewise, the brain has the tendency to fill in blanks and inconsistencies in a memory by making use of the imagination and similarities with other memories.
Leading Questions
Much research has shown that the phrasing of questions can also alter memories. A leading question is a question that suggests the answer or contains the information the examiner is looking for. For instance, one study showed that simply changing one word in a question could alter participants' answers: After viewing video footage of a car accident, participants who were asked how "slow" the car was going gave lower speed estimations than those who were asked how "fast" it was going. Children are particularly suggestible to such leading questions.
Intrusion Errors
Intrusion errors occur when information that is related to the theme of a certain memory, but was not actually a part of the original episode, become associated with the event. This makes it difficult to distinguish which elements are in fact part of the original memory. Intrusion errors are frequently studied through word-list recall tests.
Intrusion errors can be divided into two categories. The first are known as extra-list errors, which occur when incorrect and non-related items are recalled, and were not part of the word study list. These types of intrusion errors often follow what are known as the DRM Paradigm effects, in which the incorrectly recalled items are often thematically related to the study list one is attempting to recall from. Another pattern for extra-list intrusions would be an acoustic similarity pattern, which states that targets that have a similar sound to non-targets may be replaced with those non-targets in recall. The second type of intrusion errors are known as intra-list errors, which consist of irrelevant recall for items that were on the word study list. Although these two categories of intrusion errors are based on word-list studies in laboratories, the concepts can be extrapolated to real-life situations. Also, the same three factors that play a critical role in correct recall (i.e., recency, temporal association, and semantic relatedness) play a role in intrusions as well.
Types of Memory Bias
A person's motivations, intentions, mood, and biases can impact what they remember about an event. There are many identified types of bias that influence people's memories.
Fading-Affect Bias
In this type of bias, the emotion associated with unpleasant memories "fades" (i.e., is recalled less easily or is even forgotten) more quickly than emotion associated with positive memories.
Hindsight Bias
Hindsight bias is the "I knew it all along!" effect. In this type of bias, remembered events will seem predictable, even if at the time of encoding they were a complete surprise.
Illusory Correlation
When you experience illusory correlation, you inaccurately assume a relationship between two events related purely by coincidence. This type of bias comes from the human tendency to see cause-and-effect relationships when there are none; remember, correlation does not imply causation.
Mood Congruence Effect
The mood congruence effect is the tendency of individuals to retrieve information more easily when it has the same emotional content as their current emotional state. For instance, being in a depressed mood increases the tendency to remember negative events.
Mood-State Dependent Retrieval
Another documented phenomenon is mood-state dependent retrieval, which is a type of context-dependent memory. The retrieval of information is more effective when the emotional state at the time of retrieval is similar to the emotional state at the time of encoding. Thus, the probability of remembering an event can be enhanced by evoking the emotional state experienced during its initial processing.
Salience Effect
This effect, also known as the Von Restorff effect, is when an item that sticks out more (i.e., is noticeably different from its surroundings) is more likely to be remembered than other items.
Self-Reference Effect
In the self-reference effect, memories that are encoded with relation to the self are better recalled than similar memories encoded otherwise.
Self-Serving Bias
When remembering an event, individuals will often perceive themselves as being responsible for desirable outcomes, but not responsible for undesirable ones. This is known as the self-serving bias.
Source Amnesia
Source amnesia is the inability to remember where, when, or how previously learned information was acquired, while retaining the factual knowledge. Source amnesia is part of ordinary forgetting, but can also be a memory disorder. People suffering from source amnesia can also get confused about the exact content of what is remembered.
Source Confusion
Source confusion, in contrast, is not remembering the source of a memory correctly, such as personally witnessing an event versus actually only having been told about it. An example of this would be remembering the details of having been through an event, while in reality, you had seen the event depicted on television.