Explanations for forgetting: Interference

What is interference, and what is the difference between proactive and retroactive interference?

• Interference: An explanation for forgetting (loss of ability to recall info previously learned) in terms of one memory disrupting the ability to recall another - most likely to occur when 2 memories have some similarity

  • Proactive interference (PI): Past learning interferes with current attempts to learn something eg. Can’t remember new password because you still recall your old one

  • Retroactive interference (RI): Current attempts to learn something interfere with past learning eg. Can’t remember the french word for something, because you have been learning Spanish

Explain a key study that supports proactive interference

• Underwood (1957)

• Analysed findings from many studies and concluded that when participants have to learn a series of word lists, the recall of the lists encountered later are worse

• If they memorised 10+ lists, they remembered around 20% 24 hours later

• If they only learned one list, recall was over 70%

Explain a key study that supports retroactive interference

• Müller and Pilzecker (1900)

• Gave participants a list of nonsense syllables to learn for 6 minutes and then asked them to recall them, after a retention interval

• Performance was less good if they were given an intervening task before recall (describing landscape paintings)

Explain a key study that demonstrates the impact of the similarity of test materials on interference

• McGeogh + McDonald (1931)

• Gave participants a list of 10 adjectives, then a rest of 10 mins where they learnt list B, before recall

• If list B was:

  • Synonyms: Recall = 12%

  • Nonsense: Recall = 26%

  • Numbers: Recall = 37%

• Therefore, interference is strongest the more similar the items are - only interference (not decay) can explain such effects

Explain a key study that demonstrates the effect of interference in everyday life

• Baddeley + Hitch (1977)

• Investigated rugby players recalling names of teams they had played during the season - some had missed games due to injury

• Players who had played more games forget proportionally more due to interference - this would not have happened if decay theory was correct (in that case, all players should have forgotten a similar amount since the time period was the same for all players

How do the key studies link to issues and debates?

• The studies do not seem to break any ethical issues

• Some studies lack ecological validity

• Rugby players are not representative + thus the findings are not generalisable

• Reductionist: Doesn’t consider whole picture so possibly discounting other explanations (retrieval failure), but provides a lot of evidence for this explanation because it has been isolated

Explain this evaluation point: Researchers have questioned whether interference effects actually cause a memory to disappear, or if they’re temporary

• Ceraso (1967) found that, if memory was tested again 24 hours later, recognition (accessibility) showed considerable spontaneous recovery, whereas recall (availability) stayed the same

• This suggests that interference occurs because memories are temporarily not accessible, rather than actually being lost (unavailable)

• This study could lack ecological validity

• This research supports the view that interference affects availability rather than accessibility

Explain this evaluation point: The research used to support interference may not be applicable in the real world

• One issue with the evidence offered in support of both pro- and retroactive interference concerns the methodology of the studies

• Most of the research has often used rather artificial lists of words and/or nonsense syllables, thus the findings may not relate to everyday uses of memory, which tends to not involve word lists.

• Plus, participants may lack motivation to remember the lists in such studies, and this may allow interference effects to appear stronger than they actually are

• This research is low in ecological validity

• Counter: Interference had been observed in everyday situations

Explain this evaluation point: Interference effects do not occur that often in everyday life thus the application of this theory is limited

• Another criticism of research into interference is that, while interference effects do occur in everyday life, they don’t occur that often

• Anderson (2000) concluded that there is no doubt that interference plays a role in forgetting, but how much can be attributed to it is unclear

• Rather special conditions are required for interference to lead to forgetting - the 2 memories need to be quite similar

• Thus, interference is considered a relatively unimportant explanation for everyday forgetting

• This means that other theories are needed to provide a complete explanation of forgetting

Explain this evaluation point: Interference had real world application to advertising

• There is a considerable body of research on the effects of interference when people are exposed to adverts from competing brands within a short time period

• Danaher et al. (2008) found that both recall and recognition of an advertiser’s message were impaired when participants were exposed to 2 ads for competing brands within a week - they suggest that 1 strategy might be to enhance the memory trace by running multiple exposures to an ad on one day rather than spread these out over a week, which results in reduced interference from competitor’s ads

• This shows how interference research can help advertisers maximise the effectiveness of their campaigns and target their spending most effectively

Explain this evaluation point: There is evidence that some are less affected by proactive interference than others

• Kane and Engle (2000) demonstrated that individuals with a greater WM span were less susceptible to proactive interference

• The researchers tested this by giving participants 3 word lists to learn - those with low WM spans showed greater proactive interference when recalling the second and thirds lists than those with higher spans

• A further test suggested that having a greater WM span meant having greater resources to consciously control processing and counteract the effects of proactive interference

• This highlights the role that individual differences play in how people are affected by interference