Explanations for forgetting: Interference

    Cards (10)

    • Interference theory
      • Interference is when two pieces of information disrupt each other
      • Forgetting occurs in LTM because we can't get access to memories even though they are available
    • Types of interference
      Proactive interference (PI)
      • PI occurs when older memory disrupts a newer one
      • For example, a teacher learns many names in the past and can't remember names of her current class
      Retroactive interference (RI)
      • 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 previous students
    • Interference is worse when memories are similar
      • This may be because:
      • In proactive interference previously stored information makes new information more difficult to store
      • In retroactive interference, new information overwrites previous memories which are similar
    • McGeoch and McDonald (1931) Effects of similarity: Procedure
      • Ppts were asked to learn a list of words to 100% accuracy (recall perfectly)
      • Then they were 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 same meanings as the originals
      • Group 2: antonyms - words had opposite meanings to originals
      • Group 3: unrelated - words unrelated to the original ones
      • Group 4: consonant syllables
      • Group 5: three-digit numbers
      • Group 6: no new list - ppts just rested (control condition)
    • McGeoch and McDonald (1931) Effects of similarity: Findings and Conclusion
      • Performance depended on the nature of the second list. The most similar material (synonyms) produced the worst recall
      • This shows that interference is strongest when the memories are similar
    • One strength is some support for interference in real-world situations
      • Baddley and Hitch (1977) 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 (injuries). Those who played most (more interference) had poorest recall
      • This shows that interference operates in some everyday situations, increasing the validity of the theory
    • Counterpoint for support for interference in real-world situations:
      • Interference in everyday situations is unsual because the necessary conditions are relatively rare e.g. similarity of memories/learning does not occur often
      • Therefore most everyday forgetting may be better explained by other theories (e.g. retrieval failure due to lack of cues)
    • One limitation is that interference effects may be overcome using cues
      • Tulving and Psotka (1971) gave ppts lists of words organized into categories (not told what they were)
      • Recall of first list was 70% but fell with each new list (proactive interference). When given a cued recall test (names of categories) recall rose again to 70%
      • This shows that interference causes just a temporary loss of access to material still in LTM - not predicted by theory
    • Another strength is support from drug studies
      • Material learned just before taking diazepam recalled better than a placebo group one week later - this is retrograde facilitation (Coenen and Van Luijtelaar 1997)
      • The drug stopped new information reaching brain areas that process memories, so it could not retroactively interfere with stored information (Wixted)
      • This shows that the forgetting is due to interference - reducing the interference reduced the forgetting
    • Evaluation extra: Validity issues
      • Lab studies of interference have tight control of confounding variables (e.g. time), thus 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 (e.g. revising for exams)
      • This means that because research is mostly lab-based it may overestimate the importance of interference as a cause of forgetting
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