Explanations of forgetting: 1.Proactive and retroactive interference

Interference

Forgetting because one memory blocks the recall of another, causing one or both memories to be forgotten. The degree of forgetting it often greater when the memories are similar.

Proactive interference

Forgetting occurs when older memories (already sorted) disrupt the recall of newer memories. The degree of forgetting is greater when the memories are similar.

Example - your teacher has learned so many names in the past that she has difficulty remembering the names of her current class.

Retroactive interference

Forgetting occurs when newer memories disrupt the recall of all the memories already sorted. The degree of forgetting is greater when the memories are similar.

Example - your teacher has learned so many new names that she has difficulty remembering the names of her students last year.

Key study: Retroactive interference -Postman (1960)

Aim - to investigate how retroactive interference affects learning.

Method - A lab experiment was used. Participants were split into two groups. Both groups had to remember a list of paired words e.g cat-tree, jelly-moss, book-tractor. Group A (the experimental group) also had to learn another list of words where the second paired word if different e.g cat-glass, jelly-time, book-revolver. Group B (the control group) were not given the second list. All ppts were asked to recall the words on the first list.

Results - the recall of the control group was more accurate than that of the experimental group.

Key study: Proactive interference - Keppel and Underwood (1962)

Aim - Keppel and Underwood (1962) examined the effect of proactive interference on long-term memory.

Method - participants were presented with meaningless three-letter consonant trigrams ( e.g THG) at different intervals (3,6,9 seconds etc). To prevent rehearsals the participants had to count backwards in threes before recalling. Participants were asked to come back at later stages to take part in a few trials of the task which involved them learning new trigrams.

Results - ppts typically recalled the trigrams that’s were presented first, irrespective of the interval length. They were also poor at recalling later trigrams as earlier learning of trigrams had interfered with later learning.

Postman (+) Retroactive interference is supported by research

A strength of the interference theory that there is valid evidence from laboratory studies to support it. Postman (1960) asked participants to learn a list of paired words. They found that the recall for the original list of words was the poorest when participants were asked to learn a second list of words compared to participants that were not us to learn another list. This is a strength of interference because the findings demonstrate forgetting occurs when one memory blocks another as the theory claims which suggests the theory is valid.

Postman (+) Lab experiments have high control

A strength of Postman (1960) is that it is a lab experiment and has high control over extraneous variables and therefore can establish cause and effect. For example, we can be confident that the IV cause the DV. This is a strength because the results of this study are unlikely to be affected by co-founding variables and we can therefore be confident that the findings that learning similar material can cause forgetting are internally valid.

Keppel and Underwood (+) Proactive interference is supported by research

A strength of interference theory is that there is evidence from laboratory studies to support it. Keppel and Underwood (1962) found that ppts were able to remember trigrams well in the first trials and they had to undertake to learn them. When participants came back for later trials to learn new trigrams they were very poor at recalling them. This shows that interference prevented the learning of the trigrams in later trials because the trigrams in the first trial will remembered well as there was no other new information preceding it. The trigrams in the later trials were not recalled well as the earlier learning of trigrams interfered with later learnings. This is a strength of interference because the findings demonstrate that forgetting occurs when one memory blocks another as the theory claims. Therefore the theory of proactive interference is valid.

Keppel and Underwood (-) studies that support interference tend to be lab based

A limitation of interference is that studies that support the theory tend to be laboratory based and have low ecological validity. For example, the study by Keppel and Underwood involved participants recalling trigrams at different time intervals. This not an everyday task and doesn't really in a realistic way so it lacks mundane realism. This is a limitation of interference because the theory may not be a valid explanation of forgetting in the real world so it has low external validity.