It would seem that someone who followed the advice so far in this chapter would have a hard time forgetting things. Encoding information efficiently, practicing deep processing, relying on rehearsal strategies, and so on, should make memories resistant to fading. Of course many people do have excellent memories, and that can be a real advantage for them. But as it turns out, forgetting is also adaptive: We need to forget some things if we wish to remember efficiently. Piling up facts without distinguishing the important from the trivial is just confusing. Nonetheless, most of us forget more than we want to and would like to know why. Let's take a look at some of the reasons why information gets lost over time by focusing on the major explanations for forgetting.

In the early days of psychology, in an effort to measure pure memory loss independent of personal experience, Hermann Ebbinghaus (1885/1913) memorized long lists of nonsense syllables—such as bok, waf, or ged—and then tested his retention over a period of several weeks. Most of his forgetting occurred soon after the initial learning and then leveled off (see Figure10.8a). Generations of psychologists adopted Ebbinghaus's method of studying memory, but his method did not tell them much about the kinds of memories that people care about most.

Figure 10.8

Two Kinds of Forgetting Curves

A century later, Marigold Linton decided to find out how people forget real events rather than nonsense syllables. Like Ebbinghaus, she used herself as a subject, but she charted the curve of forgetting over years rather than days. Every day for 12 years she recorded on a 4- by 6-inch card two or more things that had happened to her that day. Eventually, she accumulated a catalog of thousands of discrete events, both trivial (“I have dinner at the Canton Kitchen: delicious lobster dish”) and significant (“I land at Orly Airport in Paris”). Once a month, she took a random sampling of all the cards accumulated to that point, noted whether she could remember the events on them, and tried to date the events. Linton (1978) expected the kind of rapid forgetting reported by Ebbinghaus. Instead, as you can see in Figure10.8b, she found that long-term forgetting was slower and proceeded at a much more constant pace, as details gradually dropped out of her memories.

Of course, some memories, especially those that mark important transitions, are more memorable than others. But why did Marigold Linton, like the rest of us, forget so many details? Psychologists have proposed four mechanisms to account for forgetting: decay, replacement of old memories by new ones, interference, and cue-dependent forgetting.

Decay One commonsense view, the decay theory, holds that memories simply fade with time if they are not accessed now and then. We have already seen that decay occurs in sensory memory and that it occurs in short-term memory as well unless we keep rehearsing the material. However, the mere passage of time does not account so well for forgetting in long-term memory. People commonly forget things that happened only yesterday while remembering events from many years ago. Indeed, some memories, both procedural and declarative, can last a lifetime. If you learned to swim as a child, you will still know how to swim at age 30, even if you have not been in a pool or lake for 22 years. We are also happy to report that some school lessons have great staying power. In one study, people did well on a Spanish test some 50 years after taking Spanish in high school, even though most had hardly used Spanish at all in the intervening decades (Bahrick, 1984). Decay alone cannot entirely explain lapses in long-term memory.

Replacement Another theory holds that new information entering memory can wipe out old information, just as writing over the contents of a hard drive will obliterate the original material. In a study supporting this view, researchers showed people slides of a traffic accident and used leading questions to get them to think that they had seen a stop sign when they had really seen a yield sign, or vice versa (see Figure10.9). People in a control group who were not misled in this way were able to identify the sign they had actually seen. Later, all the participants were told the purpose of the study and were asked to guess whether they had been misled. Almost all of those who had been misled continued to insist that they had really, truly saw the sign whose existence had been planted in their minds (Loftus, Miller, & Burns, 1978). The researchers interpreted this finding to mean that the subjects had not just been trying to please them and that people's original perceptions had been erased by the misleading information.

Figure 10.9

The Stop-Sign Study

A final perspective on forgetting is concerned with amnesia, the loss of memory for important personal information. Amnesia most commonly results from organic conditions such as brain disease or head injury, and is usually temporary. In psychogenic amnesia, however, the causes of forgetting are psychological, such as a need to escape feelings of embarrassment, guilt, shame, disappointment, or emotional shock. Psychogenic amnesia begins immediately after the precipitating event, involves massive memory loss including loss of personal identity, and usually ends suddenly, after just a few weeks. Despite its frequent portrayal in films and novels, it is quite rare in real life (McNally, 2003).

Psychologists generally accept the notion of psychogenic amnesia. Traumatic amnesia, however, is far more controversial. Traumatic amnesia allegedly involves the burying of specific traumatic events for a long period of time, often for many years. When the memory returns, it is supposedly immune to the usual processes of distortion and confabulation, and is recalled with perfect accuracy. The notion of traumatic amnesia originated with the psychoanalytic theory of Sigmund Freud, who argued that the mind defends itself from unwelcome and upsetting memories through the mechanism of repression, the involuntary pushing of threatening or upsetting information into the unconscious.

Most memory researchers reject the argument that a special unconscious mechanism called “repression” is necessary to explain either psychogenic or traumatic amnesia (Rofé, 2008). Richard McNally (2003) reviewed the experimental and clinical evidence and concluded, “The notion that the mind protects itself by repressing or dissociating memories of trauma, rendering them inaccessible to awareness, is a piece of psychiatric folklore devoid of convincing empirical support.” The problem for most people who have suffered disturbing experiences is not that they cannot remember, but rather that they cannot forget: The memories keep intruding. There is no case on record of anyone who has repressed the memory of being in a concentration camp, being in combat, or being the victim of an earthquake or a terrorist attack, although details of even these horrible experiences are subject to distortion and fading over time, as are all memories.

Furthermore, repression is hard to distinguish from normal forgetting. People who seem to forget disturbing experiences could be intentionally keeping themselves from retrieving their painful memories by distracting themselves whenever a memory is reactivated. Or they may be focusing consciously on positive memories instead. Perhaps, understandably, they are not rehearsing unhappy memories, so those memories fade with time. Perhaps they are simply avoiding the retrieval cues that would evoke the memories. But a reluctance to think about an upsetting experience is not the same as an inability to remember it (McNally, 2003).

The debate over traumatic amnesia and repression erupted into the public arena in the 1990s, when claims of recovered memories of sexual abuse began to appear. Many women and some men came to believe, during psychotherapy, that they could recall long-buried memories of having been sexually victimized for many years, often in bizarre ways. For therapists who accepted the notion of repression, such claims were entirely believable (Brown, Scheflin, & Whitfield, 1999; Herman, 1992). But most researchers today believe that almost all of these memories were false, having been evoked by therapists who were unaware of the research we described earlier on the power of suggestion and the dangers of confabulation (Lindsay & Read, 1994; Lynn et al., 2015; McNally, 2003; Schacter, 2001). By asking leading questions, and by encouraging clients to construct vivid images of abuse, revisit those images frequently, and focus on emotional aspects of the images, such therapists unwittingly set up the very conditions that encourage confabulation and false memories.

Since the 1990s, accusations based on “recovered memories” have steadily declined and many accusers have reconciled with their families (McHugh et al., 2004). Yet the concept of repression lingers on. Many of its original proponents have turned to the term “dissociation” to account for memory failures in traumatized individuals, the idea being that upsetting memories are split off (dissociated) from everyday consciousness. But reviews of the research have found no good evidence that early trauma causes such dissociation (Giesbrecht et al., 2008; Huntjens, Verschuere, & McNally, 2012).

Of course, it is obviously possible for someone to forget a single unhappy or deeply unpleasant experience and not recall it for years, just as going back to your elementary school might trigger a memory of the time that you did something embarrassing in front of your whole class. How then should we respond to an individual's claim to have recovered memories of years of traumatic experiences that were previously “repressed”? How can we distinguish true memories from false ones?

Clearly, a person's recollections are likely to be trustworthy if corroborating evidence is available, such as medical records, police or school reports, or the accounts of other people who had been present at the time. But in the absence of supporting evidence, we may have to tolerate uncertainty because a person might have a detailed, emotionally rich “memory” that feels completely real but that has been unintentionally confabulated (Bernstein & Loftus, 2009). In such cases, it is important to consider the content of the recovered memory and how it was recovered.

Thus, given what we know about memory, we should be skeptical if the person says that he or she has memories from the first year or two of life; as we will see in the next section, this is not possible, physiologically or cognitively. We should be skeptical if, over time, the person's memories become more and more implausible; for instance, the person says that sexual abuse continued day and night for 15 years without ever being remembered and without anyone else in the household ever noticing anything amiss. We should also be skeptical if a person suddenly recovers a traumatic memory as a result of therapy or after hearing about supposed cases of recovered memory in the news or reading about one in a best-selling autobiography. And we should hear alarm bells go off if a therapist used suggestive techniques—such as hypnosis, dream analysis, “age regression,” guided imagery, and leading questions—to “recover” the memories (Lynn et al., 2015) These techniques are all known to increase confabulation.

A curious aspect of autobiographical memory is that most adults cannot recall any events from earlier than age 2; and even after that, memories are sketchy at best until about age 6 (Jack & Hayne, 2010). A few people can vaguely recall significant events that occurred when they were as young as 2 years old, such as the birth of a sibling, but not earlier ones (Fivush & Nelson, 2004; Usher & Neisser, 1993). As adults, we cannot remember taking our first steps, or uttering our first halting sentences. We are victims of childhood amnesia (sometimes called infantile amnesia).

Childhood amnesia is disturbing to many people, so disturbing that some adamantly deny it, claiming to remember events from the second or even the first year of life. But like other false memories, these are merely reconstructions based on photographs, family stories, and imagination. The “remembered” event may not even have taken place. Swiss psychologist Jean Piaget (1952) once reported a memory of nearly being kidnapped at the age of 2. Piaget remembered sitting in his pram, watching his nurse as she bravely defended him from the kidnapper. He remembered the scratches she received on her face. He remembered a police officer with a short cloak and white baton who finally chased the kidnapper away. But when Piaget was 15, his nurse wrote to his parents confessing that she had made up the entire story. Piaget noted, “I therefore must have heard, as a child, the account of this story . . . and projected it into the past in the form of a visual memory, which was a memory of a memory, but false.”

Of course, we all retain procedural memories from the toddler stage, when we first learned to use a fork, drink from a cup, and pull a wagon. We also retain semantic memories acquired early in life: the rules of counting, the names of people and things, knowledge about objects in the world, words and meanings. Moreover, toddlers who are only 1 to 2 years old often reveal nonverbally that they remember past experiences (e.g., by imitating something they saw earlier); and some 4-year-olds can remember experiences that occurred before age 2½ (Bauer, 2002; McDonough & Mandler, 1994; Tustin & Hayne, 2010). What young children do not do well is encode and retain their early episodic memories—memories of particular events—and carry them into later childhood or adulthood. They cannot start doing this consistently until about age 4½ (Fivush & Nelson, 2004).

Freud thought that childhood amnesia was a special case of repression, but memory researchers today think that repression has nothing to do with it, and they point to better explanations (Bauer, 2015):

1. Brain development. The prefrontal cortex, and other parts of the brain involved in the formation or storage of events, are not well developed until a few years after birth (McKee & Squire, 1993; Newcombe, Lloyd, & Balcomb, 2012). In addition, the brains of infants and toddlers are busily attending to all the new experiences of life, but this very fact makes it difficult for them to focus on just one event and shut out everything else that's going on—the kind of focus necessary for encoding and remembering (Gopnik, 2009).

2. Cognitive development. Before you can carry memories about yourself with you into adulthood, you have to have a self to remember. The emergence of a self-concept usually does not take place before age 2 (Howe, Courage, & Peterson, 1994). In addition, the cognitive schemas used by preschoolers are very different from those used by older children and adults. Only after acquiring language and starting school do children form schemas that contain the information and cues necessary for recalling earlier experiences (Howe, 2000). Young children's limited vocabularies and language skills also prevent them from narrating some aspects of an experience to themselves or others. Later, after their linguistic abilities have matured, they still cannot use those abilities to recall earlier, preverbal memories because those memories were not encoded linguistically (Simcock & Hayne, 2002).

3. Social development. Preschoolers have not yet mastered the social conventions for reporting events, nor have they learned what is important to others. As a result, they focus on the routine aspects of an experience rather than the distinctive ones that will provide retrieval cues later, and they encode their experiences far less elaborately than adults do. Instead, they tend to rely on adults' questions to provide retrieval cues (“Where did we go for breakfast?” or “Who did you go trick-or-treating with?”). This dependency on adults may prevent them from building up a stable core of remembered material that will be available later on (Fivush & Nelson, 2005). But as children get older, their conversations with parents help them develop their own autobiographical memories, and thus play an important role in ending childhood amnesia (Reese, Jack, & White, 2010).

Nonetheless, our first memories, even when they are not accurate, may provide useful insights into our personalities, current concerns, ambitions, and attitudes toward life. What are your first memories—or, at least, what do you think they are? What might they tell you about yourself?