The Seven Sins of Memory

Transience refers to the general deterioration of a specific memory over time. Much more can be remembered of recent events than those further in one's past. This is especially true with episodic memory, because every time an episodic memory is recalled, it is re-encoded within the hippocampus, altering the memory each time one recalls it. Transience is caused because of interference. There are two types of interference: proactive interference (old information inhibits the ability to remember new information), and retroactive interference (new information inhibits the ability to remember old information).

One of Schacter's examples [2] of transience is a study[3] of how well undergraduates remembered how they found out about the O. J. Simpson trial verdict immediately after, 15 months, and 32 months later. After three years, fewer than 30 percent remembered accurately, and nearly half had major errors.

This form of memory breakdown involves problems at the point where attention and memory interface. Common errors of this type include misplacing keys or eyeglasses, or forgetting appointments because at the time of encoding sufficient attention was not paid to what would later need to be recalled.

Blocking is when the brain tries to retrieve or encode information, but another memory interferes with it. Blocking is a primary cause of Tip of the tongue phenomenon (a temporary inaccessibility of stored information).

Misattribution entails correct recollection of information with incorrect recollection of the source of that information. For example, a person who witnesses a murder after watching a television program may incorrectly blame the murder on someone he or she saw on the television program. This error has profound consequences in legal systems because of its unacknowledged prevalence and the confidence which is often placed in the person's ability to impart correctly information critical to suspect identification.

One example Schacter gives[4] of eyewitness misattribution occurred in connection with the Oklahoma City bombing in 1995. Two days before, the bomber rented a van, but an employee there reported seeing two men renting it together. One description fit the actual bomber, but the other description was soon determined to be of one of a pair of men who also rented a van the next day, and were unconnected with bombing.

Schacter also describes how to create misattribution errors using the DRM procedure. Subjects are read a list of words like sharp, pin, sewing, and so on, but not the word needle. Later subjects are given a second list of words including the word *needle*, and are asked to pick out which words were on the first list. Most of the time, subjects confidently assert that *needle* was on the first list.[5]

Suggestibility is somewhat similar to misattribution, but with the inclusion of overt suggestion. It is the acceptance of a false suggestion made by others. Memories of the past are often influenced by the manner in which they are recalled, and when subtle emphasis is placed on certain aspects which might seem likely to a specific type of memory, those emphasized aspects are sometimes incorporated into the recollection, whether or not they occurred. For example, a person sees a crime being committed by a redheaded man. Subsequently, after reading in the newspaper that the crime was committed by a brown-haired man, the witness "remembers" a brown-haired man instead of a redheaded man.

Loftus and Palmer's work into leading questions is an example of such suggestibility.

The sin of bias is similar to the sin of suggestibility in that one's current feelings and worldview distort remembrance of past events. This can pertain to specific incidences and the general conception one has of a certain period in one's life. Memories encoded with a certain amount of stimulation and emotion are more easily recalled. Thus, a contented adult might look back with fondness on his or her childhood, induced to do so by positive memories from that time, which might not be representative of his/her average mood during his/her childhood.

This failure of the memory system involves the unwanted recall of information that is disturbing. The remembrance can range from a blunder on the job to a truly traumatic experience, and the persistent recall can lead to formation of phobias, post-traumatic stress disorder, and even suicide in particularly disturbing or intrusive instances.