• Created by: an_kxkx
  • Created on: 27-11-19 15:37


  • forgetting due to one memo blocks another
  • 2 pieces of info confliting with each other 
  • interference makes it harder for us to locate memories, which is experienced as forgetting
  • there are 2 types of interference, retroactive interference, and retroactive inteference 
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  • new info interferes w// recall of older info 
  • old info is under attack
  • investigated by Underwood and Postman (1960)
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  • lab exp w// two groups, control and experimental
  • both were given a list of paired words
  • exp group was given another list with the same first words from each list
  • control group didn't get a second list
  • they were tested on recall of the first word list


  • recall was better in the control group, suggesting that restroactive interference of the second world list affected recall for the exp group 
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  • old info interferes w// the ability to recall new info
  • new info is under attack
  • investigated by Underwood (1957)

after looking @ studies into forgetting over a 24 hour period and found that if ppl previously learnt 15 or more word lists in the same experiment, then recall was at around 20% a day later. But if they hadn't learnt any earlier lists, recall was at 80%

concluded that proactive interference from previous lists affected the ppl's ability to remember later ones 

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McGeoch and McDonald (1931)

Aim: to investigate the effects of similarity on interference

Method: studied RI by changing the amount of similarity between 2 sets of words. 6 groups of ppts learned a 10 word list till they could recall them w// 100% accuracy, they then learned a new list. diff groups learned diff lists:

  • group 1: synonyms 
  • group 2: antonyms
  • group3: word unrelated to the original list
  • group 4: consonant syllables
  • group 5: 3 digit numbers
  • group 6:no new list 

Findings: when recalling the originals, performance depended on the 2nd list. synonyms produced the worst recall

Conclusion: interference is stronger when memos are similar (shown in the poor performance of synonym recall

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Aim: to investigate interference in a natural everyday setting 

Method: interviewed rugby players and aksed them to recall the names of the teams that they had played over a season. the time interval was, however, some players had missed some of the games due to injury.

Findings: found that the players that played most games porportionately forgot more than those who played the least games

Conclusion: suggests that interference occurs in real life too as the time delay was the same. 

- If decay is correct, then they should all have forgotten similar amounts of info, but they didn't.  So it suggests that the extra information interferes so can't acess the memories as well. 

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  • supported by studies from Underwood and Baddeley and Hitch validate the theory
  • real life applications via tv ads (Danaher et al 2008) and Baddley and Hitch 
  • Underwood used lab studies which have more control over extraneous variables


  • lab studies lack ecological validity so can't be generalised as easily to real life
  • retrivel failure and cues may offer a more valid explantion to forgetting
  • interference more occur more in lab studies due to the artificial stimuli used 
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