Forgetting

• Forgetting is when learnt information can't be retrieved
• Experimenters on memory assume that if you can't repost a memory, its forgotten
• Forgetting info from STM is an availability problem.

  Info no longer available due to limited capacity or duration of STM

  Info is displayed or decayed
• Long term forgetting can be caused by:

  • Decay
  • Info stored is hard to retrieve (accessibility problem)
  • Info is confused (interference problem)
• Ability to remember affected by having learnt something similar before or since --> interference
• What is retroactive interference

  New info interferes with ability to recall older info
• What proactive interference

  Older info interferes with the ability to recall new info
• Underwood and postman (1960) retroactive interference study

  • Lab experiment
  • Ps given list paired word to learn
  • Experimental group given 2nd list
  • Both experimenter and control group tested on first list
  • Recall better in control group
  • Retroactive interference affected experimental group
• Underwood (1957) proactive interference study

  • Looked at results of studies into forgetting over 24 hours
  • Leant 15 or more word lists during experiment
  • Recall of last word list was 20%
  • If hadn't learnt earlier lists - recall 80%
  • Proactive interference of earlier lists affected ability to remember new ones
• Strengths of interference theory

  • Supported by many studies (highly controlled lab experiments)
  • Evidence of interference in forgetting in real world
• Weaknesses of interference theory

  • Effects greater in artificial setting than real life
  • Doesn't look at biological or cognitive processes involved in forgetting
  • Doesn't fully explain how interference occurs
• Recall can depend on getting the right cues
• Another theory of memory is that being able to recall info depends on getting the right cue. Forgetting is retrieval failure.
• More chance of retrieving memory if the cue is appropriate

  Cues can be internal or external
• Tulving and Psotka (1971) Forgetting in LTM - Procedure

  • Compared theory of interference and cue dependent forgetting
  • Each P given 1, 2, 3, 4, 5 or 6 list of 24 words
  • Each list 6 categories of 4 words
  • Words in category order
  • In one condition P had to recall all words
  • Another condition P given category names and had to recall words
• Tulving and Psotka (1971) Forgetting in LTM - Findings

  • In condition 1 (total free recall) evidence of retroactive interference
  • Ps with 1 or 2 lists had better recall
  • In condition 2 (cued recall) retroactive interference disappeared and the number of lists was irrelevant
  • Recall about 70% for each list
• Tulving and Psotka (1971) Forgetting in LTM - Conclusion

  • Interference hadn't caused forgetting
  • Memories more accessible if cue used
• Tulving and Psotka (1971) Forgetting in LTM - Evaluation

  • Lab experiment = highly controlled condtions
  • Reduced effects of extraneous variables
  • Lack ecological validity
  • Only tested memory of words so can't generalise to other types of memory
• Strengths of cue dependent memory

  • Best explanation for forgetting in LTM
  • Strongest evidence
  • Most forgetting is retrieval failure
  • Virtually all memory is available we just need a cue