Interference : reasons for forgetting

• Interference theory

  Interference : when two pieces of information disrupt each other

  Forgetting occurs in long term memory as we can't get access to memories even though they are available.

  • Proactive interference - older memories disrupt new memories. This is due to previous information being similar to new information making it hard to store
  • Retroactive interference - new memory disrupts old memories. This is due to new information overwriting old information which is similar
• McGeoch and McDonald - effects of similarity 


  Procedure - Participants were asked to learn a list of words to 100% accuracy. They were then given a new list to learn. The new material varied in the degree to which it was similar to the old :

  1. synonyms
  2. antonyms
  3. unrelated
  4. consonant syllables
  5. numbers
  6. no list

  Findings - performance depended on the nature of the second list. The most similar list produced the worst recall e.g. in the synonyms group. This shows that interference is strongest when memories are similar.
• Evaluation

  One strength is some support for interference in real world situations. Baddeley and Hitch asked rugby players to recall the names of teams they had played against during a rugby season. Players did not play the same number of games due to injuries. Those who played the most games (more interference) had poorest recall. This shows that interference operates in some everyday situations, increasing the validity of the theory. However, interference is unusual in everyday situations as the necessary conditions are relatively rare.
• Evaluation

  One limitation is that interference effects may be overcome using cues. Tulving gave participants lists of words organised into categories. Recall of the first list was 70% but fell with each new list (interference). When given a cued recall test, and recall rose again to 70%. This shows that interference causes temporary loss of access to material still in long term memory which is not predicted by this theory.
• Evaluation

  One limitation is validity issues. Lab studies of interference have tight control of confounding variables, thus making a clear link between interference and forgetting. However, most research is unlike everyday forgetting. In everyday life we often learn something and recall it much later. This means that as research is mostly lab based it may overstimulate the importance of interference as a cause of forgetting.