Introduction and STM

  • Forgetting refers to a person loss of the ability to recall or recognise a thing that they have previously learnt.
  • Decay in STM - suggests that if rehersal does not take place, the passage of time will cause the memory to disappear or decay. Explains why forgetfullness increases with time.
  • Peterson and Peterson (1959) - discovered that if participants were prevented from rehersing a list of words, their recall dropped form 80% after 3 seconds to 20% after 18 seconds. Study does not have high ecological validity - doesnt represent a real world situation - DC.
  • Displacement in STM - suggests that new information recieved by the STM overwrites or displaces previous information. When STM full, new information will push old information out.
  • Waugh and Norman (1965) - used serial probe technique to investigate the issue of displacement and decay. Found that both decay and displacement together explain forgetting, but that displacement would have a stronger effect. 
  • Reitman (1974) - gave participants words to remember and then an interference task that wouldnt interfere with the informaiton being remembered (e.g. listening for a tone). After 15 seconds, recall had dropped by 21%, which suggetss that decay rather than displacement is responsible. Low EV as not real worl situaiton - DC.
1 of 3


  • Decay theory - explains how things are forgotten because the physical trace of a memory has dissapeared due to passage of time. 
  • Lashley (1931) - trained rates to learn mazed and the removed secitons of the brain. Found a relationship between the amount of brain removed and amount of forgetting. Suggests memories have a physical trace suporting decay theory. Problem with generalisability - cant generalise results to humans as higher cognitive beings and behaviour is more complex - study invalid.
  • Jenkins and Dallenbach (1924) - participants asked to recall nonesense syllables after being asleep for 8 hours. Those were able to remember more than those who had been awake for 8 hours. Disagrees with decay theory as if decay theory was correct, both groups should forget the same amount. Problem with internal validity.
  • Interference. Proactive interference - previous learning interferes with later learnning. Retroactive interference - later learning disrupts earlier learning. 
  • Underwood and Postman (1960) - Participants had to learn a series of word pairs then presented with first word adn had to recall the paired word. Then had to learn a different list with the same stimulus word but different responce word. Tested on both lists - recall of response word poorer and affected by earlier and later learning. Low EV - only valid if tested on students.
2 of 3

LTM (continued) and conclusion

  • Cue dependant - forgetting due to inability to access memory. Unavailable as right cue is not present.
  • Abernethy (1940) - students who sat a test in the same room by the same instructors as in their normal lessons got higher marks. Environment was a cue for memory. However, generalisability - only valid when applying to students, cant generalise to rest of population as sample were students so does not represent whole population.
  • Goodwin et al (1969) - people who had forgot things whilst drunk could remember them when drunk again. However, ethics - risk to harm.
  • In conclusion, many explanations for foregtting in STM and LTM, including, decay, displacement and cue dependant. All have supportive and contradictory evidence.
3 of 3


No comments have yet been made

Similar Psychology resources:

See all Psychology resources »See all Memory resources »