Memory Errors and Forgetting

Everyone forgets things—birthdays, names, where we left our keys—because memory is not a perfect recording system. It is fragile, reconstructive, and shaped by attention, meaning, context, and time. Psychologists study forgetting to understand why memory sometimes fails and how these errors occur.

Encoding Failure

Sometimes forgetting happens before a memory is even stored. This is called encoding failure. If you didn’t pay attention to details in the first place, they were never encoded—so there’s nothing to retrieve later.

Can you accurately recall what the front of a U.S. nickel looks like? When researchers Raymond Nickerson and Marilyn Adams (1979) asked this question, they found that most Americans don’t know which one it is. The reason is most likely encoding failure. Most of us never encode the details of the nickel. We only encode enough information to be able to distinguish it from other coins.

If we don’t encode the information, then it’s not in our long-term memory, so we will not be able to remember it.

Show Answer

The correct nickel is (c).

Encoding and Recoding

The process of encoding is selective, and in complex situations, relatively few of many possible details are noticed and encoded. The process of encoding always involves recoding.

recoding

Recoding is taking information from the form it is delivered to us and then converting it in a way that we can make sense of it.

For example, you might try to remember the colors of a rainbow by using the acronym ROY G. BIV (red, orange, yellow, green, blue, indigo, violet). The process of recoding, or reorganizing the colors into a mnemonic, can help us to remember. Creating mental images to make information more memorable or linking new information to what you already know (“elaborative encoding”), also involves recoding.

However, recoding can also introduce errors—when we accidentally add information during encoding, then remember that new material as if it had been part of the actual experience.

Memory Retrieval: A Reconstructive Process

Not all forgetting occurs at encoding. Sometimes the memory is stored but hard to access. Retrieval itself is a reconstructive process—each time we recall a memory, we rebuild it from pieces.

Two major retrieval phenomena:

1. The Testing Effect (or retrieval practice effect)
   • Retrieving information strengthens it, making future retrieval easier (Roediger & Karpicke, 2006). This is why practice tests dramatically improve learning.
2. Retrieval-Induced Forgetting
   • Strengthening one memory can weaken related memories (Anderson et al., 1994).
   • For example, you’re studying vocabulary for a language class—say, 10 Spanish kitchen words. But you practice retrieving only five of them. Later, when tested on all 10, you remember the five you practiced—but surprisingly, you do worse than expected on the other five (never practiced) words. Retrieving some items actually weakened your access to related items in the same category.

Reconstruction and Distortion

Memories—especially older ones—are reconstructions, not perfect “playbacks.” We weave the concrete bits and pieces of events in with assumptions and preferences to form a coherent story (Bartlett, 1932).

For example, if during your 10th birthday, your dog got to your cake before you did, you would likely tell that story for years afterward. Say, then, in later years you misremember where the dog actually found the cake, but repeat that error over and over during subsequent retellings of the story. Over time, that inaccuracy would become a basic fact of the event in your mind.

Just as retrieval practice (repetition) enhances accurate memories, so will it strengthen errors or false memories (McDermott, 2006). Sometimes memories can even be manufactured just from hearing a vivid story. Consider the following episode, recounted by Jean Piaget, the famous developmental psychologist, from his childhood:

One of my first memories would date, if it were true, from my second year. I can still see, most clearly, the following scene, in which I believed until I was about 15. I was sitting in my pram . . . when a man tried to kidnap me. I was held in by the strap fastened round me while my nurse bravely tried to stand between me and the thief. She received various scratches, and I can still vaguely see those on her face. . . . When I was about 15, my parents received a letter from my former nurse saying that she had been converted to the Salvation Army. She wanted to confess her past faults, and in particular to return the watch she had been given as a reward on this occasion. She had made up the whole story, faking the scratches. I therefore must have heard, as a child, this story, which my parents believed, and projected it into the past in the form of a visual memory. . . . Many real memories are doubtless of the same order. (Norman & Schacter, 1997, pp. 187–188)

Piaget’s vivid account represents a case of a pure reconstructive memory. He heard the tale told repeatedly, and doubtless told it (and thought about it) himself. The repeated telling cemented the events as though they had really happened, just as we are all open to the possibility of having “many real memories … of the same order.” The fact that one can remember precise details (the location, the scratches) does not necessarily indicate that the memory is true, a point that has been confirmed in laboratory studies, too (e.g., Norman & Schacter, 1997).