Explanations for forgetting: interference

• What does interference mean in memory?


  when 2 pieces of information disrupt each other
• why does forgetting occur in LTM


  we cant get access to memories even though they are available
• what is proactive interference


  when an older memory disrupts a new one.
• give an example of proactive interference 


  a teacher learns many names of students in the past that they can remember the names of their current class
• what is retroactive interference?


  when a newer memory disrupts an older one
• give an example of retroactive interference 


  a teacher learns many new names this year and cant remember the names of previous students
• interference is worse when memories are similar


  This may be because:

  • in proactive interference, previously stored information makes new information difficult to store
  • in retroactive interference, new informations overwrites previous memories which are similar
• who studied the effects of similarity 


  McGeoch and McDonald (1931)
• procedure of McGeoch and McDonald

  • participants were asked to learn a list of words to 100% accuracy (they could recall them perfectly)
  • they were then given a new list to learn. The new material varied in the degree to which it was similar to the old
  • Group 1: synonyms - words had the same meanings as the originals
  • Group 2: antonyms - words had opposite meanings to the originals
  • Group 3: unrelated - words unrelated to the original ones
  • Group 4: consonant syllables
  • Group 5: 3 digit numbers
  • Group 6: no new list - participants just retested (control condition)
• findings of the McGeoch and McDonald study


  performance depended on the nature of the second list. the most similar material (synonyms) produced the worst recall
• conclusions of the McGeoch and McDonald study


  interference is strongest when the memories are similar.
• One strength is some support for interference in real world situations

  Baddeley and Hitch (1977) asked rugby players to recall the names of teams they played against during a rugby season. Players didnt play the same number of games due to injuries. Those who played the most (most interference) had poorest recall. This shows that interference operates in some everyday situations, increasing the validity of the theory
• one strength is support for interference in real world situations: counterpoint

  interference in everyday situations is unusual because the necessary conditions are relatively rare e.g. similarity of memories/learning doesnt occur often. therefore most everyday forgetting may be better explained by other theories e.g. retrieval failure due to a lack of cues
• one limitation is that interference effects may be overcome using cues

  Tulving and Psotka (1971) gave participants lists of words organised into categories (not told what they were). recall of the first list was 70% but fell with each new list (interference). when given a cued recall test (names of categories) recall rose again to 70%. this shows that interference causes a temporary loss of access to material still in LTM - not predicted by the theory