5. Explanations for forgetting: Interference theory

define interference

when one memory disrupts the ability to recall another

more likely to happen if the memories are similar

define proactive interference

previously learnt information interferes with the new information you are trying to store

define retroactive interference

a new memory interferes with older ones

Underwood (1957)

showed that proactive interference could be equally significant

completed a meta analysis

concluded that when pps have to learn a series of word lists, they do not learn the word lists encountered later as effectively as world lists encountered earlier on

found that if pps memorised 10 or more lists then recall over 24 hours was 20%. if pps learned 1 word list, recall over 24 hours was 70%

Mceoch and McDonald (1931)

A: investigated effect of similarity on memory

P: gave pps a list of 10 adjectives, pps were given time to learn these, pps were given a resting interval of 10 minutes in which they learned a second list. 6 groups of pps who had to learn different types of lists

F: found that as similarity of the new word list to the old word list decreased, number of items from the first list recalled increased

if list B was a list of synonyms of list A, recall was 12%

if list B was nonsense syllables, recall was 26%

if list B was numbers, recall was 37%

C: suggests interference is worse when the learning is similar

Muller and Pilzecker (1900)

A: identify retroactive interference

P: pps were given a list of nonsense syllables to learn for 6 minutes. after a retention interval they were asked to recall the lists

F: performance was worse if pps had been given an intervening task between initial learning and recall (e.g. shown landscape pictures and asked to describe them)

C: suggests that the intervening task produced retroactive interference

one limitation of interference theory is the supporting evidence comes from lab studies which use artificial materials

Muller and Pilzecker’s (1900) research provided evidence that retroactive interference increased forgetting by show that pps who had been given an intervening task in between learning a list of nonsense syllables recalled less of the list

artificial lists of nonsense syllables do not reflect interference in everyday life (lacks semantics)

lacks mundane realism which leads to poor ecological validity

one strength of interference theory is it can be applied to advertising

Danaher et al (2008) found that both recall and recognition of an advertiser’s message was impaired when pps were exposed to two advertisements for competing brands within a week

supports the concept of proactive interference and is problematic for companies that spend significant budgets on advertising = would need to consider strategies (e.g. running the same advert several times in one day rather than over a week)

research on proactive interference has real-world applications

one limitation of interference theory is individual differences

Kane and Engle (2000) pps were given 3-word lists to learn. pps with low working memory showed greater proactive interference when recalling the second word list then did pps with higher spans

a further test showed that having a greater working memory span meant having greater resources to consciously control processing and counteract the effects of proactive interference

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