explanations for forgetting : interference

• Interference: when two pieces of information are in conflict. forgetting occurs in LTM because we can't get access to memories even though they are available.
• proactive interference:

  • PI occurs when an older memory disrupts a newer one.
  • for example, a teacher learns many names in the past and can't remember the names of her current ones.
• retroactive interference:


  • RI happens when a newer memory disrupts an older one. for example, a teacher learns many new names this year and can't remember the names of her former students.
• interference is worse when memories are similar:

  • this may be because:
  • in PI previously stored information makes new information more difficult to store.
  • in RI new information overwrites previous memories that are similar.
• what is the key study associated with interference?

  • mcgeoch and mcdonald: effects of similarity.
• procedure of mcgeoch and mcdonald: effects of similarity: participants asked to learn a list of words to 100% accuracy (i.e. can recall perfectly)

  then they were given a new list to learn. new material varied in the degree to which it was similar to the old:

  • synonyms
  • antonyms
  • unrelated
  • consonant syllables
  • three-digit numbers
  • no new list- participants rested (control condition).
• findings and conclusions of mcgeoch and McDonald: effects of similarity:

  • performance depended on the nature of the second list. the most similar material (synonyms) produced the worst recall.
  • when the participants were given very different material, such as three-digit numbers, the mean number of items recalled increased.
  • this shows that interference is strongest when the memories are similar.
  • in group 1 it is likely that the words with the same meanings as the original lists blocked access or that the new material became confused with the old material.
• limitations of research into this subject: use of artificial materials:

  • the stimulus material used is often word lists. this is more realistic than consonant syllables, but is still quite different from things we remember in everyday life. for example, in everyday life we remember people's faces, their birthdays, the ingredients of our favourite pizza, etc. the use of artificial materials makes interference much more likely in the lab. it may not be a likely cause of 'everyday' forgetting.
• strength of interference theory: real life studies have supported:

  • baddeley and hitch asked rugby players to recall the names of teams they had played so far in that season, week by week. accurate recall did not depend on how long ago the match took place. more important was the number of games played in the meantime. this study shows that interference explanations can apply to at least some everyday situations.
• limitation of interference: overcome using cues:

  • tulving & psotka gave participants 5 lists of 24 words, each organised into six categories. categories were not explicit but it was assumed they would be obvious when presented. recall was about 70% for the first list, but fell as each additional list was learned, presumably due to interference. however, when given a cued recall test (told the names of the categories) recall rose again to about 70%. memories of the words were stored in LTM but interference prevented access to them. when given a cue, it was easier to access the forgotten words.