Understanding Forgetting and Why We Do Forget
Forgetting is the loss of, or inability to retrieve, information from long-term memory.
From forgetting where you left your keys to forgetting to return a phone call, memory failures are an almost daily occurrence and it is both a real part of people’s everyday lives and an important factor in learning.
Forgetting is so common that we typically rely on numerous methods to help us remember important information, such as jotting down notes in a daily planner or scheduling important events in the calendar.
As you are frantically searching for your missing car keys, it may seem that the information about where you left them is permanently erased from your memory. However, forgetting is generally not about actually losing or erasing this information from your long-term memory Opens in new window.
Forgetting typically involves a failure in memory retrieval. While the information is somewhere in your long-term memory, you are not able to actually retrieve and remember it.
The Ebbinghaus Forgetting Curve
Psychologist Hermann Ebbinghaus was one of the first to scientifically study forgetting. In experiments where he used himself as the subject, Ebbinghaus tested his memory using three-letter nonsense syllables. Using previously known words would have made use of previously existing knowledge and association in his memory.
In order to test his memory for new information, Ebbinghaus tested his memory for periods of time ranging from 20 minutes to 31 days.
His results, plotted in what is known as the Ebbinghaus forgetting curve, revealed a relationship between forgetting and time. Initially, information is often lost very quickly after it is learned. Factors such as how the information was learned and how frequently it was rehearsed play a role in how quickly these memories are lost.
The forgetting curve also showed that forgetting does not continue to decline until all of the information is lost. At a certain point, the amount of forgetting levels off.
What exactly does this mean? It indicates that information stored in long-term memory Opens in new window is surprisingly stable.
Theories of Forgetting: Explanations Why Forgetting Occur
1. Forgetting as Interference
Some experts explain forgetting with the concept interference, the loss of information because something learned either before or after detracts from understanding (Howe, 2004).
For example, students learn that the rule for forming singular possessives states that an apostrophe s is added to the singular noun. If their understanding of the rule for forming singular possessives later interferes with learning the rules for forming plural possessives and contractions, proactive interference, prior learning interfering with new understanding, has occurred.
On the other hand, if the rules for forming plural possessives confuse their prior understanding, retroactive interference has occurred. Students’ understanding of plural possessives and contractions can interfere with their understanding of singular possessives and vice versa.
Studying closely related ideas—such as communism and fascism, longitude and latitude, and adding fractions with similar and different denominators—together is perhaps the most effectively strategy that exists for reducing interference (Hamilton, 1997). In doing so, we recognize similarities and differences and identify areas that are easily confused.
We can also reduce interference by reviewing previously studied material before we move to a new topic, which activates prior knowledge and provides a bridge to the new topic.
2. Forgetting as Retrieval Failure
Retrieval is the process of pulling information from long-term memory Opens in new window back into working memoryOpens in new window, and many researchers believe that “forgetting” is actually the inability to retrieve information from long-term memory (Williams & Zacks, 2001).
We have all had the experience of realizing that we know a name, fact, or some other information, but we simply cannot pull it up.
Retrieval depends on context and the way information is encoded (Williams & Zacks, 2001). For instance, you know a person at school, but you cannot remember his name when you see him at a party; his name was encoded in the school context, and you are trying to retrieve it in the context of the party.
Meaningfulness is the key to retrieval. The more detailed and interconnected knowledge is in long-term memory, the easier it is to retrieve (Nuthall, 1999a).
Practice to the point of automaticity also facilitates retrieval (Chaffen & Imreh, 2002). When students know their math facts to the point of automaticity, for example, they can easily retrieve them for use in problem solving, leaving more working memory space to focus on solutions.
3. Failure to Store
We also forget information because it never actually made it into long-term memory. Encoding failures sometimes prevent information from entering long-term memory.
In one well-known experiment, researchers asked participants to identify the correct U.S. penny out of a group of incorrect pennies (Nickerson & Adams).
Try doing this experiment yourself by attempting to draw a penny from memory, and then compare your results to an actual penny.
How well did you do?
Chances are that you were able to remember the shape and color, but you probably forgot other minor details. The reason for this is that only details necessary for distinguishing pennies from other coins were encoded into your long-term memory.
4. Motivated Forgetting
Sometimes, we may actively work to forget memories, especially those of traumatic or disturbing events or experiences. The two basic forms of motivated forgetting are: suppression, a conscious form of forgetting, and repression an unconscious form of forgetting.
However, the concept of repressed memories is not universally accepted by all psychologists. One of the problems with repressed memories is that it is difficult, if not impossible, to scientifically study whether or not a memory has been repressed.
Also note that mental activities such as rehearsal and remembering are important ways of strengthening a memory, and memories of painful or traumatic life events are far less likely to be remembered, discussed or rehearsed.