Interference

Interference: Forgetting because one memory disrupts another, causing one or both memories to be distorted or forgotten. It is thought to be prominent in the LTM as when memories are stored they are available even if we can’t access them as interference makes it harder for us to locate them.

Proactive Interference: When an older memory, already stored, disrupts the recall of newer memories. The degree of forgetting is greater when the memories are similar.

Retroactive Interference: When a newer memory disrupts the recall of older memories, already stored. The degree of forgetting is greater when the memories are similar.

McGeoch and McDonald (1931): Studied retroactive recall by making participants learn 1 set of words until their recall was 100%. Then they had to learn a second of either synonyms, antonyms, unrelated words, consonant syllables, three digit numbers or no new list. When participants were asked to recall the first list, those that learnt the synonyms did the worst. This showed that interference is strongest when memories are similar.

Explanation of Effects of Similarity: Could be because previously stored information makes new similar information more difficult to store or that new information overwrites previous similar memories because of the similarity.

Evidence for Real-World Interference: Baddeley and Hitch (1977) asked rugby players about teams they had played during the season. Those that had been at more games had the poorest recall.

Counterpoint to Real-World Interference: Conditions necessary for interference to occur are relatively rare because it is uncommon for two memories to be fairly similar in order to interfere with each other. This happens sometimes in everyday life, but not often.

Interference Overcome by Cues: Tulving and Psotka (1971) gave participants lists of words in two categories, one list at a time. Recall averaged 70% for the first list but as more lists were added, recall worsened. However when the participants were told the names of the categories, recall rose again to 70%.

Support From Drug Studies: Coenen and Luijtelaar (1997) found when a list of words was learned under the influence of diazepam, recall one week later was poor but if the list was learned before the drug was taken, later recall was better than the placebo showing that the drug improved recall of materials learned beforehand. Wixted suggested this is because the drug prevents new information reaching parts of the brain involved in processing memories. This is showing evidence of retrograde facilitation.