Introduction
The mysteries of remembering and forgetting have fascinated humankind for hundreds, even thousands of years. In the late nineteenth century, memory was one of the areas of interest to early psychologists such as Hermann Ebbinghaus and William James. Ebbinghaus conducted an experiment in 1885 in which he tested his own memory, and he then graphed a forgetting curve, which illustrated how much information on a particular list he forgot over time. James wrote about the tip-of-the-tongue phenomenon in 1890, evocatively describing the gap that exists in the place of a name one is trying to recall as “intensely active” and containing the “wraith of the name” beckoning within it.
Though often reliable—and, at times, astoundingly accurate—human memory is fallible. Daniel Schacter, a prominent cognitive psychologist, has referred to this duality as “memory’s fragile power.” During the twentieth century, scientists who studied artificial intelligence occasionally clashed with neuroscientists on the relative merits of machine-based models of memory. Later, scientists uncovered the deleterious effects of some pharmaceutical compounds on memory, which suggests that drugs may help trauma victims reduce or erase their recollection of events, thereby lowering the risk of post-traumatic stress disorder (PTSD) or facilitating the treatment of PTSD.
Memory’s power is evident in what it makes possible in everyday life: a sense of personal history, knowledge of countless facts and subtle concepts, learning and mastery of complex skills, and even personal identity. The fragile side of memory is also quite apparent in both mundane and dramatic ways. Most people struggle to remember the names of others they have just met or of those they have not seen for some time. People forget events rapidly or gradually; even wonderful memories seem to fade in time. The past is distorted with sometimes surprising results that belie strongly held beliefs or deep-seated feelings.
Physical Causes
Research on the causes of memory failure has examined the range of forgetting, from the more normal tip-of-the-tongue phenomenon to total amnesia. Memory loss as a result of brain damage caused by disease and injury has also been the focus of research. Head injuries, for example, can cause difficulties remembering certain information. In cases of brain tumor, in which certain parts of the brain are removed, aspects of memory may be irreparably lost. Alcoholics who drink heavily for many years frequently encounter difficulties remembering; this condition is sometimes termed Wernicke-Korsakoff syndrome. Those who use drugs may also experience memory impairment; actual brain damage may occur in such cases. Strokes or internal injuries can also cause memory loss, as can epilepsy; during an epileptic seizure, oxygen is not getting to the brain, a condition that may result in brain damage and memory loss.
Older people with Alzheimer’s disease
or other types of dementia
have trouble remembering. For years, many believed that the hormonal changes associated with menopause produced memory impairment, but the evidence has not supported this as a causal factor. Aging itself seems to affect memory retrieval in a phenomenon once known as benign senescent forgetfulness, but later referred to as age-associated memory impairment (AAMI). The reasons for this fairly common condition are not completely understood but may include changes in brain physiology and diminished care, concern, or motivation. With the aging of the population, concern over the extent and social cost of Alzheimer’s disease has risen. Perhaps as a result, new medications known as cholinesterase inhibitors have been developed and marketed. Although these drugs do not cure or reverse the course of the disease, there is reliable evidence of their capacity to slow its associated declines.
It is not known exactly how people learn or why they remember or forget. Some psychologists posit that the brain’s chemical makeup and activity (particularly involving those substances known as neurotransmitters) are central to learning and remembering; others contend that the brain’s electrical activity is crucial in determining one’s memory. If there is either a chemical or an electrical abnormality in the brain, people may have difficulties in learning or in recalling information and events. With modern methodologies for brain scanning, including such noninvasive procedures as nuclear magnetic resonance (NMRI) spectroscopy, positron emission tomography (PET) scanning, and computed tomography (CT) scanning, researchers may be better able to probe various physiological reasons for forgetting. With functional magnetic resonance imaging (fMRI), it is possible to track changes in brain activity as someone, for example, attempts to remember a past event.
Theories of Normal Forgetting
One theory of forgetting holds that “forgotten” material was never learned in the first place. In other words, the information was never encoded. Another possibility is that such little importance was attached to the material that it was poorly learned—or encoded—and was subsequently forgotten. Sometimes people are overwhelmed by the sheer amount of information they must learn and are simply incapable of remembering the massive amount of material.
Another theory about forgetting suggests that material is never really forgotten; rather, people cannot find the key to retrieve the information from the brain’s filing system—its long-term memory. Nearly everyone has experienced the tip-of-the-tongue phenomenon (seeing someone at a party, for example, but being unable to remember the person’s name). Sometimes concentration aids memory retrieval; often association helps the process. At the same time, anxiety and depression can interfere with recall. Psychologists have also noted primacy and recency effects regarding memory; that is, people remember what is learned first and what is learned last most efficiently. Material that is presented in the middle tends to be more easily forgotten.
In William James’s “booming, buzzing confusion,” people frequently are unable to process adequately all the information encountered; forgetting some information is necessary. Moreover, people must often replace existing information with new information, as when a friend or family member relocates and acquires a new address and telephone number. Research on directed forgetting has shown that people are able to deal more effectively with large amounts of information by following instructions to treat some of the information as “to be forgotten.” In this way, interference is reduced and people are able to devote all of their resources to the remaining to-be-remembered information.
Other theories of normal forgetting attempt to explain the ways in which various types of interference affect people’s ability to remember material. If a student is taking classes at nine, ten, and eleven in the morning, for example, that person may have difficulty remembering material because the information from each of the three classes interferes with that of the other classes; this will be especially true if the subject matter is similar. This same process can affect memories of everything from movies to events in people’s own lives. The greater the number of similar films or events (such as dinners in the same type of restaurant) there have been, the more interference there may be. There are two types of interference, retroactive and proactive interference. In proactive interference, occurrences that come before an event or learning situation interfere with the ability to learn or remember; in retroactive interference, the occurrence that interferes with remembering comes after the event or learning situation.
People’s mental state, according to many psychologists, has much to do with the ability to learn, retain, and recall information. If people are suffering from depression, grief, or loss, the ability to remember will be severely impaired. Children who are abused often have difficulties learning and remembering because they are preoccupied with the worries and concerns caused by their traumatic home situation. People suffering from depression also may have problems remembering. Counseling or therapy will sometimes alleviate people’s emotional concerns and therefore result in better recall. Emotional problems that may be helped in this way include depression, anxiety, and fear of failure.
Psychologists have debated whether information stored in long-term memory is stored there permanently. Some memory theorists believe that a decay or fading factor is at work when people forget information. That is, memory traces naturally fade away and are lost simply because of the passage of time. If a person is a freshman in college, that student may remember many members of his or her high school senior class very well. In another ten years, however, that individual may be less able to remember high school classmates and may have forgotten some of those who were not close friends. In twenty years, more information will fade unless the person actively tries to rehearse or review the people who were in the class. For example, if people took out their high school yearbook every June for twenty years and reminisced about the people in it, they would be better able to recall the names at a twenty-fifth high school reunion.
Some theorists believe that if people can link or associate people, places, or events with other things, they may be able to recall past people or events more effectively. This theory holds that people’s minds normally tend to associate one thing with another. These “associationistic” theories are based on the idea that bonds are formed in the brain between places or bits of information. If the bonds are inadequately or poorly formed, then forgetting may occur; bonds must periodically be reformed to guard against forgetting.
The psychoanalytic (or Freudian) perspective on forgetting emphasizes the idea that people “forget” events that are emotionally traumatic. This is motivated, or purposeful, forgetting; the Freudian term for it is “repression.” An example would be a woman who, as a six-year-old girl, had been sexually molested by her father or another relative and who has since forgotten the incident. Interestingly, repression has been known to occur in both victims and perpetrators of violent crimes.
Forgetting as a By-Product of an Adaptive System
In The Seven Sins of Memory: How the Mind Forgets and Remembers (2001), Daniel Schacter presents a framework for classifying the various ways memory fails. He reviews decades of research evidence from social, cognitive, and clinical psychology, as well as later work using imaging methods that make it possible, for example, to observe changes in brain activity as someone retrieves previously learned information. Schacter suggests that like the biblical seven deadly sins—pride, anger, envy, greed, gluttony, lust, and sloth—the seven sins of memory occur frequently in everyday life.
Memory’s seven sins are transience, absentmindedness, blocking, misattribution, suggestibility, bias, and persistence. The first three are different types of forgetting. Transience involves decreasing accessibility of information, with recent evidence indicating that forgetting over time is best described mathematically as a power function; that is, the rate of forgetting slows down with the passage of time. Absentmindedness results from inattentive or shallow processing of information that in turn causes weak memories of ongoing events, such as forgetting where one recently placed an object. When absentminded lapses involve forgetting to carry out a planned action at some time in the future, such as picking up the dry cleaning on the way home from work, they are referred to as failures of prospective memory. Blocking refers to the temporary inaccessibility of information that is stored in memory. The tip-of-the-tongue phenomenon is a commonly experienced example of blocking; the incidence of this type of blocking appears to increase with aging.
The next three sins involve distortion or inaccuracy of memory. Misattribution occurs when a person attributes a recollection or idea to the wrong source, such as recalling having read something in the newspaper when, in fact, the person heard it on the radio. Another type of misattribution occurs when people falsely recall or recognize items or events that never happened. Suggestibility refers to memories that are implanted, for example, as a result of leading questions during attempts to elicit recall of past events. This phenomenon is closely related to the controversy concerning false and recovered memories of childhood sexual abuse. Bias occurs when memories of previous experiences are influenced or distorted by current knowledge, beliefs, or expectations, or by present mood and emotional states. A number of studies have identified a consistency bias in retrospection: People’s recollections tend to exaggerate the degree of similarity between their past and present feelings, attitudes, or beliefs.
The final sin, persistence, refers to intrusive recollections of traumatic events or obsessional thinking about negative symptoms and events or chronic fears. In other words, these are memories that people wish they could forget but cannot. Just as current feelings can distort recollections of past events or emotions, they can also increase the likelihood of persistence; for instance, memories whose affective tone matches a person’s current mood are more accessible.
Schacter asserts that it is wrong to view the seven sins as flaws in the design of the human memory system. Rather, they should be thought of as by-products of what he calls “otherwise adaptive features of memory.” Consider, for example, what would happen without blocking, the sin whereby information is temporarily inaccessible because of some inhibitory process. In a system without blocking, all information that is potentially relevant to what is sought would invariably and rapidly come to mind. The likely result would be massive confusion.
Ways to Minimize Forgetting
Two different types of tests are used to assess memory and learning; one type tests recognition, while the other tests recall. A multiple-choice test assesses the first type of memory, because in this type of test one needs to recognize the correct answer when one sees it. An essay examination tests recall—all the responsibility is on the learner to recall as much relevant information as possible.
Research on memory and forgetting can be applied in both academic and nonacademic settings. There are a number of things people can do to aid learning and protect against forgetting. Overlearning is one tactic that ensures that people have learned material and will remember it later. In this technique, students repeat the material by rehearsing it in their head to ensure later recall. If they need to learn a formula, they may repeat it over and over—perhaps writing it a hundred times. This can be tedious, which undoubtedly spurred the search for other options to learn and remember more effectively. Constant review is another strategy. In spaced practice, students study materials to be learned for one hour each night before the test. These students seem to remember the material better than those who spend eight hours studying the material the night before the test. (That type of study—“cramming”—is called massed practice.) For some students, cramming does work, but the material is easily forgotten immediately after the cramming session. Cramming also creates anxiety and fatigue, which may interfere with optimal performance. Some students with poor organizational skills need to expend extra effort to organize the material they have learned. They may employ index cards, for example, to help group and link relevant materials. Mnemonics are memory tricks or devices that help people recall information. The rhyme that begins “Thirty days have September, April, June, and November,” for example, helps people remember the number of days in each month. The word “homes” is frequently used as an acronym for the names of the Great Lakes: Huron, Ontario, Michigan, Erie, and Superior.
Note taking is one way to minimize forgetting; reviewing notes can help people prepare for an examination. For this to be most effective, however, people must be able to discriminate between useful and unimportant information at the time of writing the material down. The same holds true for underlining or highlighting material in books or notes. Recording lectures for later review is particularly useful in cases in which a lecturer speaks very rapidly, making effective note taking difficult.
Concentration is an important part of learning and remembering, and people often do not spend enough time concentrating intensely. It has been said that thirty minutes of concentrated, uninterrupted study is better than two hours of haphazard study. The minimizing of outside stimuli is also important; people should study in a quiet place with few distractions. Studying in the same place (and at the same time) every night is also thought to be important for optimal results. Learning should be active to minimize forgetting. Making decisions regarding material to be learned is a useful tool for facilitating learning; students may ask themselves questions about topics or subjects to learn or review. Students should be prompted to think about their own learning styles and to allot the necessary time to learn a given amount of material. Many people have their own preferred learning style. Some people learn better by seeing data and information; others assimilate information better by hearing it. Ideally, students should find and maximize their preferred mode. There are tests designed to determine a person’s preferred mode of learning.
If people are trying to assimilate too much information in too short a time, they may experience information overload. Students taking summer classes in which a semester’s worth of information is compressed into a few weeks experience this overload, as may those taking eighteen or more hours of classes in a semester. Overload may also affect someone beginning a new job that involves mastering a large amount of information or technical material. Material that is meaningful to the learner has been found to be easier to remember and recall.
Forgetting in the Courtroom
Forgetting is especially problematic when eyewitnesses are required to testify in courtroom settings. Some argue that given extensive trial preparation, the likelihood of false memories being implanted or the corruption of recall is significant. This has been a concern when prosecution is delayed, as in holocaust and war crimes. The seven sins of memory have particular relevance in this setting and have been helpful to forensic psychologists seeking to enhance the accuracy of courtroom testimony.
Bibliography
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