Forgetting in LTM

1. Forgetting in LTM • Availability vs accessibility • Interference • Suggests that information forgotten from LTM has disappeared completely • Cue dependent forgetting • Suggests that forgotten information is still stored, but is (temporarily) inaccessible www.psychlotron.org.uk

2. Interference • Forgetting occurs when information to be stored is similar to information already in LTM • Retroactive - new info ‘overwrites’ previously stored info • Proactive - previously stored info prevents new info from being stored properly • Predicts that forgetting will increase with similarity of information www.psychlotron.org.uk

3. Interference • McGeoch & MacDonald (1931) • PPs had to learn lists of adjectives, recall after a delay. Three conditions: • Did nothing between learning & recall • Learned additional unrelated material • Learned additional adjectives • Most forgetting in group 3 • Supports prediction that forgetting is a function of similarity www.psychlotron.org.uk

4. Interference • Tulving (1966) • PPs asked to free recall word lists they had previously learned • Recall tested on several different occasions • Generally, PPs recalled about 50% of the words, but not always the same 50% • Suggests that words had not disappeared but had actually been inaccessible • This is contrary to what interference theory suggests www.psychlotron.org.uk

5. Interference • Clearly it is possible to confuse similar information • Some experiments support interference theory, but they are very artificial • Information that has been forgotten often becomes recoverable later • Unlikely that interference accounts for most of the forgetting we do www.psychlotron.org.uk

6. Cue Dependent Forgetting • Forgetting occurs when information becomes inaccessible • We lack the appropriate retrieval cues that will allow us to locate it in LTM • Retrieval cues can be external (context) or internal (state) • Predicts that remembering will be better when state & context are the same as at the time of learning www.psychlotron.org.uk

7. Cue Dependent Forgetting • Smith (1970) tested recall of a word list in the original learning context or a different room • Same room – 18/80 words • Different room – 12/80 words • PPs who imagined themselves back in original room recalled avg. 17/80 • Strong evidence for role of context cues in retrieval www.psychlotron.org.uk

8. Cue Dependent Forgetting • Fair amount of support for role of state cues in forgetting/remembering e.g • Goodwin et al (1969) – heavy drinkers often forgot where they had put things when sober, but remembered once they had drunk sufficient alcohol • Eich (1980) similar findings with heavy marijuana users www.psychlotron.org.uk

9. Cue Dependent Forgetting • Much research support for basic propositions. • Retrieval seems to be most likely when conditions match those of initial learning • Does not apply equally to all types of info • E.g. procedural memories (skills) seem stable, resistant to forgetting and not reliant on retrival cues www.psychlotron.org.uk