Interference Theory

• When we forget something, is it due to the memory being gone (availability) or do we just have trouble reaching them (accessibility)
• Interference is where 2 pieces of info conflict with each other and disrupt the ability to recall the other
• Interference is said to be the main cause for forgetting memories in the LTM
• Proactive interference occurs when an older memory interferes with a newer one
• Retroactive interference happens when a new memory interferes with an older one
• Keppel and Underwood (1962) aimed to examine the effect of proactive interference on LTM
• Keppel and Underwood's research resembles Peterson and Peterson's
• Keppel and Underwood presented participants with meaningless, 3 letter consonant trigrams at different intervals (3, 6, 9 seconds, etc)
• Keppel and Underwood had participants count backwards in threes before recalling the trigrams to prevent repetition
• Keppel and underwood found that participants typically remembered the trigrams that were presented first, irrespective of the interval length
• Keppel and Underwood's research suggests proactive interference occurred and that the earlier consonants had been transferred to LTM and were interfering with the memory for the new consonants
• Underwood and Postman (1960) aimed to investigate the effect of retroactive interference on LTM
• Underwood and Postman split participants into two groups both had to remember a list of paired words. Only the second group had to remember a second list where the second paired word was different. All participants were asked to recall the first list
• Underwood and Postman found that the recall of the control group was more accurate than the recall of the experimental group
• Underwood and Postman's study suggests that learning items in the second list interfered with the participant's ability to recall the first list. An example of retroactive interference
• Interference is more likely to occur when the two pieces of information are similar- this is due to response competition
• McGeoch and McDonald (1931) studied retroactive interference by changing the amount of similarity between two sets of materials
• McGeoch and McDonald had participants learn a list of words until they could remember them with 100% accuracy, then they learned a new list of words:

  1. synonyms
  2. antonyms
  3. unrelated words
  4. nonsense syllables
  5. three-digit numbers
  6. no new list
• McGeoch and McDonald found that the more similar the second set was to the first, the less words they recalled
• McGeoch and McDonald's findings suggest that it is hardest to recall similar things, suggests interference is strongest with similar memories