Memory fails us in multiple ways. Daniel Schacter, former chair of
http://en.wikipedia.org/wiki/Seven_deadly_sins
Schacter asserts: "Memory's malfunctions can be divided into seven fundamental transgressions. These are transience, absent-mindedness, blocking, misattribution, suggestibility, bias, and persistence. The first three are described as sins of omission. These omissions result is a failure to recall an idea, fact, or event. The other four sins (misattribution, suggestibility, bias, and persistence) are sins of commission. After committing these mistakes while encoding and storing an information, event or a fact there is a form of memory present. But it is not of the desired fidelity or the desired fact, event, or ideas. It is a falsified memory. Let us look at each one of these omissions and commissions.
Transience
Transience refers to the general deterioration of a specific memory over time. As time passes memory of an event or information fades and ultimately it would be lost irretrievably. In this case the information fails to be transferred into long-term memory store. Repetition or rehearsal is the way to avoid loss of memory by transience.
Absent-mindedness
Absent-mindedness is a mental condition in which the subject experiences low levels of attention and frequent distraction. The breakdowns in attention prevent encoding the event in short-term memory in the first place. It may occur in normal persons due to inattention or distraction while hearing or doing something. But there is an abnormal condition called Attention Deficit Disorder [ADD]. Usually this condition is associated with incessant hyperactivity or hyper kinesis. Then the condition is called Attention Deficit Hyperkinetic Disorder [ADHD]. Until recently the notion among psychiatrists was ADHD occurs in children only. But there are adult cases also. Persons under stress cannot pay attention to a particular information or event.
Blocking
Blocking is when the brain tries to retrieve or encode information, but another memory interferes with it. Blocking is a primary cause of “on the tip of the tongue” phenomenon (a temporary inaccessibility of information stored in long-term memory).
Transience, absent-mindedness and blocking are all sins of omission, malfunctions that result in a loss of memory for information that we would like to remember. There are also sins of commission, in which we remember incorrect information or correct information that we would very much like to forget.
Misattribution
Misattribution of the source of a memory can cause a person to confuse an event that he or she saw in a movie or even dreamed with an event actually experienced. For example, a person who witnesses a murder after watching a television program may incorrectly blame the murder on someone she saw on the television program. This kind of 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 know the source of information important to suspect identification.
Suggestibility
Suggestibility refers to our tendency to become confused in our recollections because of comments made by others or reports in the media about what really happened. For example, a person sees a crime being committed by a redheaded man. 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. Eyewitness testimony about a crime can be incorrect because of misattribution and suggestibility, causing miscarriages of justice in our legal system.
Bias
Bias refers to the way in which our current beliefs affect our reconstruction of the past. Retrieval from the long term is biased by the way we think and feel now about the event being remembered. Thus, a contented adult might look back with fondness on their childhood, induced to do so by positive memories from that time which might not actually be representative of their average mood during their childhood.
Persistence
Persistence is not a distortion of memory, but rather an unwelcome imposition of the past in full detail. Repeated retrieval of painful memories that we would much prefer to forget is another sin of commission that we are all familiar with. 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 especially disturbing and intrusive instances.
