Case study - Memory

MSM

Atkinson & Shiffrin (1968-1971)

STM - capacity 7 ± 2 chunks

Miller 1956

Strengths of the MSM - 1

• Baddeley (1966) tested the recall of four groups of participants with different lists of words

• Baddeley found that similar-sounding (acoustic) words can get mixed up when using STM, but similar-meaning (semantic) words get mixed up when using LTM

• This suggests that there is a clear distinction between STM and LTM

Strengths of the MSM - 2

• The case study of HM who suffered from epilepsy and underwent brain surgery to correct this, removing his hippocampus

  • Following this surgery, HM could remember events and some information and details from before the surgery (LTM) but he could not form new memories (STM could not be transferred to LTM)

    • This adds weight to the argument that the brain uses separate regions or structures for STM and LTM

Limitations of the MSM - 1

• The MSM may be too simple

  • Research suggests that STM and LTM are made up of more than one store

  • The working memory model supports the above idea, as it includes five components of STM

Limitations of the MSM -2

• Baddeley (1966) used artificial stimuli instead of meaningful material

  • This suggests there is a limited application to real world memory use

  • The use of artificial tasks and applications means that the study lacks ecological validity

WMM

Baddeley & Hitch (1974)

Strengths of the WMM - 1

• The case study of KF (Shallice & Warrington, 1970) offers support for the WMM

  • KF suffered a brain injury after which his STM was severely impaired

  • KF struggled to process verbal/auditory information but his ability to recall visual information was unaffected

    • This is evidence that there are different slave systems in the working memory which code for verbal/auditory information and visual information

Strengths of the WMM - 2

• Dual-task performance effect (Baddeley, 1976) may provide evidence for the CE

  • Participants were asked to perform a digit span task (repeating a list of numbers) and a verbal reasoning task (answering true or false questions) at the same time

  • As the number of digits increased, participants took longer to answer the true/false questions (not significantly longer)

  • Baddeley concluded that the verbal reasoning task used the CE and the digit span task used the PL

Limitations of the WMM - 1

• There is a lack of detail on the role of the CE

  • This lack of detail may be due to the fact that the CE is very difficult to operationalise and measure

  • There may be more than one central component to the CE but to date, this has not been established with empirical evidence

Limitations of the WMM - 2

• The dual-task performance effect relies on highly controlled lab conditions using tasks that are unrelated to real-life scenarios

  • This lack of 'realness' lowers the ecological validity of research in this field

Lotfus & palmer (1974) - procedure

• Procedure:

  • Forty-five student participants (split into five groups) were shown films of car traffic accidents

  • After the films, each group was given a questionnaire to complete, which included a critical question in which the verb used to describe the car accident was changed:

    • 'How fast was the car travelling when it _____ the other car?

    • The verbs were: hit, contacted, smashed, collided, bumped

    • Each group had a different verb as part of their questionnaire

    • Each verb constituted one condition of the independent variable

Lotfus & Palmer - findings

• Findings:

  • The dependent variable was measured as estimated speed in miles per hour

    • The lowest estimated speed was for 'contacted' = 31.8 mph

    • The highest estimated speed was for 'smashed' = 40.8 mph

Strengths of the EWT - 1

• There is real-world application with studies into the effect of leading questions, as the findings can be applied to legal fields and the criminal justice system

  • This means that there is importance to the accuracy of EWT to ensure that innocent people are not convicted of crimes due to poor recall of events from a witness

Strengths of the EWT - 2

• Research on leading questions has led to the development of techniques designed to improve witnesses' memory retrieval, such as the cognitive interview (CI) developed by Geiselman et al. (1985)

  • The CI is now standard in many police forces, showing that research in leading questions has high ecological validity and social usefulness as it has lead to important changes in the criminal justice system

Limitations of the EWT - 1

• Lab studies (such as Loftus & Palmer 1974) lack ecological validity because they do not represent real-life situations

  • Eyewitnesses to car accidents are likely to experience high levels of stress, which does not happen with lab-based research

  • Participants in lab studies may not take the experiment seriously or give the same motivation if they were witnessing a real-life situation

  • Answers given by participants may be prone to demand characteristics

  • The above observations suggest that the research into leading questions may not have relevance to real-life EWT

Limitations of the EWT - 2

• EWT research does not account fully for individual differences

  • Some people are aware of and can avoid being affected by leading questions

  • Some people may feel over-excited, nervous, fearful having witnessed a crime in which case it would be their emotional state rather than the use of leading questions that impaired their memory

Gabbert et al. (2003) - Post event discussion - procedure

• Pairs of participants (students and older adults) each watched a different film clip of the same crime so each had a unique view of the event

• Pairs were able to discuss what they had witnessed before carrying out a recall test of the event seen in the video

Gabbert et al. (2003) - Post event discussion - findings

• A large proportion (71%) of eyewitnesses who had discussed the crime made mistakes when recalling the events

• In pairs where no discussion had taken place, 0% of mistakes in recall were made

• This suggests that PED can lead to inaccurate eyewitness testimony

Strengths of the PED - 1

• Two different populations were investigated as part of the study by Gabbert et al.: students and older adults, which gives the study high population validity

  • This suggests that PED affects people in all populations in a similar way

Strengths of the PED - 2

• The research performed by Gabbert et al. was a lab study

  • Lab studies are easy to replicate; this means there is high reliability to the findings of the investigation

Limits of the PED - 1

• There is low ecological validity because the participants, as part of Gabbert et al.'s study, knew they were taking part in a study

  • Participants were likely to have paid close attention to the details of the video clip

  • This means that the results do not reflect a real-life crime had it been witnessed

Limitations of the PED - 2

• Gabbert et al. could not explain why the effects of PED occurred so the memory distortion could be due to:

  • pressure to conform to other eyewitnesses

  • poor memory, where people build new information into their memory of the event and are unable to distinguish between what they have seen and what they have heard