MODULE 4
Theories of Retention

Everyone has experienced forgetting. We forget the name of an acquaintance in the middle of an introduction, or a telephone number that we just looked up, or the events of a few days or many years ago.

Forgetting is closely related to negative transfer. It is not a function of time. but of events that take place in time. Some experimental evidence suggests that emotional factors can influence forgetting, too.

• As you read through the text, keep the following questions in mind.
• What is the trace or disuse theory of forgetting?
• State the interference theory.
• What is proactive inhibition? Retroactive inhibition?
• Describe a study comparing these theories.
• Which one did the evidence support?
• What is motivated forgetting? What did Freud call it?

INCORRECT THEORIES ABOUT FORGETTING

Most people believe that forgetting takes place with the passage of time when learned material is not usedÄthe "disuse" theory. This theory might include the idea of memory "traces" in the brain which decay with time until they disappear. At that point, forgetting would be complete. However, there is very little evidence to support the disuse or trace theories, and some evidence tends to refute them. An example from everyday life is bicycle riding. Once this skill is learned, it does not disappear, even following many years of "disuse."

INTERFERENCE

Proactive inhibition interferes with new learning

By far the best supported theory of forgetting states that it is due to interference. As we saw in the module on transfer, previous learning can interfere with new learning and result in negative transfer. The term for this interference is proactive inhibition. The typical transfer design can be used to test for proactive inhibition by adding a test of recall.

	Task A	Task B	Recall Task B
Experimental Group	Learn to some level of mastery	5 Practice trials	Test
Control Group	Rest	5 Practice Trials	Test

If we give both groups an equal amount of practice on task B, we would expect equal scores on a recall test of B -- unless task A has facilitatory or inhibitory effects.

Retroactive inhibition interferes with retention of things learned previously

If the experimental group recalls more than the control group, positive transfer has occurred. If the experimental group recalls less, then negative transfer has occurred, and this effect is called proactive inhibition.

The example of trying to learn a friend's new married name demonstrates how previous learning may interfere with new learning. The concept of interference can also be used to explain forgetting. The reason we forget is that new learning interferes with the recall of something previously learned.

Consider the experiment below:

	Task A	Task B	Recall Task A
Experimental Group	Learn to Mastery	Learn to Mastery	Test
Control Group	Learn to Mastery	Rest	Test

If the experimental group does poorly on the test of recall, it is apparent that the learning of task B has interfered with the recall of task A. Since task B is acting "backwards" in time to inhibit the recall of task A, we call this phenomenon retroactive inhibition. Such findings have led to the inter theory of forgetting; that is, new learning interferes with the recall of old learning.

Types of Interference

Proactive (acts forward) -- Old learning interferes with the recall of new learning.

Retroactive (acts backward) -- New learning interferes with the recall of old learning.

Minami and Dallenbach (1946) tested the interference theory of forgetting with cockroaches. The cockroach was selected as an experimental subject because of its peculiar characteristic of remaining immobile for as long as 24 hours if placed in a warm, damp passageway. In this experiment, all cockroaches had learned to avoid a certain corner of the cage where electric shock was administered. The cockroaches in the experimental group were then put into the immobile condition. When retested 24 hours later, they showed almost no loss of retention. But, for a control group of cockroaches, allowed to be normally active for the same period of time, considerable relearning was necessary. The experiment gives strong support for the interference theory over the disuse or trace theory.

Further experimental support for the interference theory is found in an early study by Jenkins and Dallenbach (1924). Subjects learned lists of nonsense syllables at different times during the day. Some of these lists were learned just prior to going to sleep. When tested at various time intervals after learning, recall was much better when the intervening time had been filled primarily with sleep rather than a comparable period of being awake.

Recall after a period of sleeping and a period of being awake (shows that retention is much higher after period of sleep than after period of being awake.

The conditions under which proactive or retroactive inhibition occur are essentially the same as for negative transfer. That is, when the stimuli are identical and the response different, the greatest amount of inhibition occurs.

MOTIVATED FORGETTING

Unpleasant memories may be repressed

No doubt, Interference resulting from other learning activities is an important component of forgetting, but the theory in no way takes into account the possibility of motivation being involved in remembering or forgetting. When we forget to take our medicine is it because ongoing activities have interfered with remembering or is it because we find the medicine unpleasant? The Internal Revenue Service reports that the most common mistake individuals make in filling out income tax forms is forgetting to sign their names when they owe additional taxes. However, this forgetting does not take place nearly as often when the individual expects a refund. The role of motivation is clear.

The forgetting of unpleasant memories was called repression by Freud. Freud and other psychoanalysts often spoke as if all of forgetting were due to repression. However, only those events which produce guilt or anxiety should be considered repressed.

Homme (1966) viewed repression as a special case of avoidance learning. For example, if recalling details of an accident aroused painful feeling, then thinking about something else will be negatively reinforced. The painful memory would be avoided. This form of self-conditioning eventually leads to avoidance behaviors which successfully interfere with the recall of the aversive event.

Repression may also reduce the retention of memories related to those repressed

Although neither Freud's nor Homme's theories of repression have been fully verified by experiments, there is ample evidence that repression does take place. Zeller (1950) had subjects learn a series of nonsense syllables. Immediately thereafter, subjects worked on a second task which was unrelated to the first and for which they were severely punished by being told they were stupid -- that they should be able to learn more rapidly. It was hypothesized that the subjects who were punished during the second task would tend to repress the whole learning activity, so that their recall of the first task would be diminished also. When subjects were tested in the recall of the first task, the "repression" group did recall significantly fewer items from the first task than did a control group.

SUMMARY OF THEORIES OF FORGETTING

Each explanation of forgetting emphasizes a somewhat different aspect. Certainly, interference effects resulting from retroactive and proactive inhibitions are responsible for much loss in retention. The evidence for decay in memory trace with disuse is weak, although such phenomena may be a component of short-term memory. Motivated forgetting is a reality, although the conditions under which it occurs are not well understood.

MODULE 4
PROGRESS CHECK 1

Now test yourself without looking back.

Use the following experimental results for questions 1-3.

	Task A	Task B	Recall A	Recall B
Group 1	8 practice trials	8 practice trials	test	test
Group 2	8 practice trials	---	test	----
Group 3	---	8 practice trials	---	test

1. If we compare Group 1 and Group 2 on the recall of Task A, what would we be looking for?
a. Proactive inhibitions
b. Retroactive inhibitions
c. Any difference in difficulty of learning between Task A and Task B

2. If we compare Groups 1 and 3 on the recall of Task B, we would be looking for:
a. proactive inhibitions.
b. retroactive inhibitions.
c. differences between tasks A and B.

3. The following data were obtained from Groups 1 and 2 on the recall of Task A.

Mean Number of Responses
Correctly Recalled

Group 1 8
Group 2 10

The poorer performance of Group 1 would be due to_______________________________________

4. The "decay of memory trace" theory:
a. is the theory most widely held by laymen.
b. attributes loss in retention largely to disuse.
c. is well validated by laboratory research.
d. (none of these)

5. Which is true of the interference theory of forgetting?

a. It is not as well supported as other theories.
b. It implies that the activity intervening between learning and testing is important.
c. (neither)


6. Ms. Brown has received a C.O.D. delivery of a new mink stole which she regrets having purchased without her husband's knowledge. She is unable to find her purse even though It is in the place where she always keeps it. We would call this form of forgetting____________________________________

ANSWER KEY

Retroactive means to act backwards. For example, a retroactive pay raise means you get money for the work you did before the raise.

Which of these is an example of retroactive inhibition?
a. Old learning interferes with the recall of new learning.
b. New learning interferes with the recall of old learning.


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The designs used in testing for proactive inhibition and negative transfer are similar. The difference is that in negative transfer we are interested in how much the previous learning interfered with the acquisition of a new task, while in proactive inhibition we are interested in how the previous learning interfered with the retention or performance of a new task.

Which of these would be considered a proactive inhibition study?
a. An Air Force study which found that men previously trained on equipment Z made more errors while learning to operate equipment A than did "fresh" trainees.
b. An Air Force study which found that men previously trained on equipment R made more mistakes on operating the new model S than did men who had not been trained on equipment R, even though both groups had learned to operate model S with equal skill.

Retroactive inhibition occurs when new learning interferes with the recall of old. Which of these may be an example of retroactive inhibition?