Previously, storage process were discussed and some factors were identified which can affect how well something is stored in LTM.

However, we have not directly addressed why information, once stored in LTM, is forgotten. According to the Atkinson & Shiffrin model, once in LTM, information is permanently stored. So, why is it often forgotten, especially when we need it most, like when taking an exam or trying to remember someone's name that you should know?

Decay Theory

Decay Theory suggests that memories spontaneously fade with time.

This theory seems quite in line with our everyday experience that in general, the longer the passage of time, the poorer our memory of the event.

How then can we remember (given this theory) some significant events that took place years ago while many events of a month ago are forgotten?

One possible explanation is that the stronger the initial learning, the stronger the trace-----Also, periodic recall of the memory re-stamps it in.

Which of the following would be evidence which seems to contradict simple decay theory?
As students learn more and more concepts in a semester, they have more and more difficulty remembering concepts learned earlier in the semester.
Sometimes we can recall some bit of information today that we were not able to recall yesterday.
Sometimes we can remember more details of our trip to Washington a year ago better than our trip to South Shore Plaza a month ago.

Obliterative Subsumption

This is a variation of decay theory and suggests that memories are lost because they may be subsumed under more general, superordinate pieces of information.

The idea is that over time details are lost because they are absorbed into their superordinate concepts. That is, details and specific examples of concepts are lost, but the essence of the more general concept is remembered.

Given this theory, what might students be most likely to recall from the segment on instrumental conditioning?
the difference between positive and negative reinforcement
the idea that the consequences of behavior, either reinforcing or aversive, affect the future likelihood of behavior
the response patterns associated with variable interval schedules
the effects of prior intermittent reinforcement on extinction

Our everyday experiences are consistent with this theory, but unfortunately, there is little other evidence for it pro or con.

Interference Theory

Interference theory suggests that forgetting is due to active interference from other learning.

There are two kinds of interference: retroactive interference and proactive interference.

Retroactive interference occurs when new learning interferes with the ability to recall older material.

Proactive interference occurs when older material interferes with the ability to remember newer material.

Jerry is taking a Chemistry course and is finding it more and more difficult to remember new compounds as the semester progresses. This would be an example of
retroactive interference
proactive interference
obliterative subsumption

Mary is taking a history course and as the semester progresses has more and more difficulty remembering the dates learned early in the semester. This would most likely be an example of
retroactive interference
proactive interference
obliterative subsumption

People often report going to the supermarket to buy a short list of items and then forgetting one of those items. After the shopper has left the store, the missing item is invariably remembered. Probably what is happening is that the presence of a huge amount of goods in the supermarket elicits interfering memories.

One implication of interference theory is memories are not lost, but simply cannot be located due to the interfering effects of other memories.
true
false

Interference theory would suggest that the older a memory, the greater the opportunity for new experiences to interfere with the memory. Thus, in general, older memories would be recalled more poorly than recent memories.

With respect to the forgetting of older memories, both decay and interference theories predict the same outcome.
true
false

In order to determine which of these theories more accurately describes why forgetting occurs, a researcher would need some situation where the 2 theories make opposite predictions to test the adequacy of these theories.

Luckily, in a classic experiment, Jenkins and Dallenbach (1924) did just that. They compared retention scores for 2 groups of subjects after the passage of the same amount of time. However, subjects in one group spent this time sleeping, the other group spent this time awake.

Decay theory would predict
the awake group would do more poorly.
the sleep group would do more poorly.
the awake and sleep group should equally recall the passage.

Interference theory would predict
the awake group would do more poorly.
the sleep group would do more poorly.
the awake and sleep group should equally recall the passage.

Results supported the predictions of interference theory.

Problems

1. Decay theory won't totally die and decay

Although interference theory is now the dominant theory of forgetting, this experiment did not completely knock out decay theory. Considerable forgetting did occur even for the sleep group. This may have been due to interference from other material learned inside or outside of the lab, or it may have been due to decay.

Other attempts to test decay theory have involved attempting to modify an organism's metabolism to see the effect on retention.

If decay is due to normal metabolic processes, then a higher metabolism should lead to more decay.
true
false

Rozin and Gleitman (1971) trained fish to avoid shock in a shuttle box. Fish spent the retention interval either in the training temperature or in a hot tank. Hot tank fish forgot more.

Does this result support decay theory?
yes
no

However, it is only inferred that hot tanks increase metabolism which in turn affects the memory trace. Interference remains the dominant explanation for forgetting.

2. Interference may not be a general explanation for forgetting but rather an explanation for the forgetting of certain kinds of material.

Explanations for interference effects rely upon the idea of response competition, that we confuse similar memories so don't come up with what we are looking for.

However, that may be a bigger problem in the rote memorization tasks used in laboratory research than in real life where meaningful material is learned. When items in memory are meaningful and logically arranged, why should we confuse them?

The importance of retrieval cues

We learn things in particular stimulus contexts. The particular stimuli present during learning become part of our memories and can later serve as cues to elicit memory. If they are not present when we try to recall something, our performance may suffer.

Specifically, a learning theorist by the name of Underwood viewed memory as a collection of different types of information, called memory attributes. For example, when we experience an event, we may experience it through a particular sensory modality or modalities (we hear or see it). It may occur in a particular place (as on a particular page or in a room or country). We may experience it in a particular physiological or emotional state (happy, fearful, or intoxicated).

According to Underwood, there are ten types of memory attributes and in various combinations they make up a memory. Not all attributes may be part of a given memory (For example, if we are not aware of the date that some event occurred, we will not remember it on its anniversary.)

How are memory attributes involved in forgetting?

First, interference causes forgetting when we can’t differentiate between memories.

Conversely, information contained in a memory attribute can act to differentiate memories and help their recall.

Jeremy prefers to vacation at a beach. He has spent time on the Cape, on a beach in Cape Hatteras, North Carolin, at Old Orchard Beach in Maine, and on Waikiki Beach in Hawaii. Which beach trip would be easier to recall in detail?
Cape Cod
Cape Hatteras
Old Orchard Beach
Waikiki Beach

Second, if we are in the presence of a stimulus that is part of the original memory, this will act to retrieve the memory. Or conversely, if the stimulus is not present, we may have difficulty remembering. This sort of stimulus is called a retrieval cue. Retrieval cues help us find information in our memories.

Several types of retrieval cues exist.

If the cue is identical to the kind of information you are trying to recall, it is called an identity cue.

Which of the following types of test question is based upon the presence of identity cues?
fill in the blank
essay
multiple choice
true-false

Which list of items would be easiest to recall if one is given the cue “birds”?
hawk, pencil, chair, balloon
car, truck, girl, pigeon
river, goose, turnip, color
robin, eagle, duck, sandpiper
All choices should be equally easy.

In this case, “birds” would be an associate cue, a cue which identifies a category of items.

If one can put items into an organizational structure, rather than in random order, they will be more easily recalled. This is called a frame, a third type of cue.

Since we often learn material in a particular physical environment, being in that environment again can provide a contextual cue.

Even the physiological or emotional, state we happen to be in when learning can be the source of a retrieval cue. We recall information better if we are in the same physiological or emotional state. This is called state-dependent learning.

A student has studied in the library for hours preparing for a final exam. Yet, when taking the exam in the classroom, she has difficulty remembering the material she studied. Her problem is probably due to the absence of which type of retrieval cue?
associate cue
frame
contextual cue
state-dependent

When Jennifer is depressed, she remembers all the unhappy events in her life, but has trouble remembering happy times even though she has experienced happiness in the past. Which type of retrieval cue is responsible for this phenomenon?
associate cue
frame
contextual cue
state-dependent

When George studies, he not only tries to learn the important concepts but also tries to learn the organization of the concepts in the readings. What type of retrieval cue is he attempting to use?
associate cue
frame
contextual cue
state-dependent

Construction Error

To repeat, memory doesn't work like a tape recorder or camcorder, faithfully recording things as they actually occur in the external world.

We have already seen examples of this in the storage process. However, this is also true when it comes to retrieval.

If memories were like videotapes, the big problem would be in finding the recording (and we know how hard that can be). Once we have found the recording or the memory, though, all we need to do is to play it back.

Unfortunately, it is more complicated than that. It seems that memories are constructed from what is stored in LTM. We often remember themes rather than details. We may just remember part of an experience and fill in the missing gaps based upon what is logical or upon what we already know from past experience. In other words, we construct our memory of some event from bits and pieces.

For example, most of us can accurately remember which family members were present at last year’s Thanksgiving dinner. What’s more, we accurately remember that turkey was served with stuffing and gravy.

What is the most probable explanation for the accuracy of this memory?
We remember these details of last Thanksgiving’s meal.
Since the same family members are always present and since turkey and stuffing are always served, logically this must have been the case last year.

Generally, construction is a good thing. We are generally right in how we fill in missing gaps and make the overall memory coherent and consistent with the facts.

However, sometimes we can be wrong and this can lead to inaccuracies.

For example, in a classic study, Elizabeth Loftus had subjects view a film of a traffic accident and then answer a question about how fast the cars were going: "About how fast were the cars going when they _________ (contacted, hit, bumped, collided, or smashed) each other?"

In this case, subjects gave increasingly higher speed estimates. Moreover, this wording resulted in subjects reconstructing their original memories. When tested a week later, 32 percent of the "smashed" subjects responded positively when asked if they had seen broken glass at the scene (even though none was present).

Based upon Loftus’s study, can entirely new memories be constructed?
yes
no

Repression

The idea here is that we may be motivated to forget materials or events which pose some degree of emotional threat to us. This is what Freud was talking about when he spoke of repression.

Rather than talk about the existence of some unconscious mind full of repressed memories (Freud's ideas are hard to prove), an alternative explanation for forgetting of traumatic events is that painful memories produce anxiety which in turn motivates us to steer clear of these memories in our memory searches.

Which of the following would be the clearest example of forgetting due to repression?
When John was in high school, he was repeatedly bullied by other students. He has since graduated, gone to college, and settled in another state. He has no recollection of this experience.
As a child, Jane was repeatedly molested by her brother. Even though she still frequently sees her brother, she has no memory of this incident.
When Patty was failing her chemistry class, she had repeated anxiety attacks. Now, as a Psychology major, she seldom remembers this experience.

Review questions

Which theory of forgetting suggests that memory of an event could be lost forever?
repression
interference
decay

Our everyday experience of being able to remember important concepts while forgetting details is consistent with which theory of forgetting?
obliterative subsumption theory
decay theory
interference theory
All of the above

The fact that we are able to recall something today that we could not recall yesterday is evidence in favor of
obliterative subsumption theory
decay theory
interference theory

At the end of a semester, a psychology professor who is teaching personality theories asks the class what it recalls about Freud’s theory, the first theory covered in the course. Individual students call out “stages of development’, “repression”, “libido”, “conflicts with mother” but can’t seem to recall more details about these general ideas. These results are consistent with which theory of memory?
obliterative subsumption theory
decay theory
interference theory

Overall, there is more experimental evidence supporting ___________ than ___________ theory.
interference; decay
decay; interference

Both decay and interference theories predict worse memory for older experiences.
true
false

It is so difficult for Sabrina to ever remember how sad she was after the break-up with her fiancé 2 years ago. She is now engaged to Ralph and is incredibly happy. What best explains why Sabrina has difficulty remembering how sad she had been?
construction error
proactive interference
retroactive interference
state-dependent memory

In general the construction process in memory leads to accurate recall.
true
false

Is it possible to remember things which didn’t happen?
yes
no

In the space below, please write any comments or questions about the tutorial.