Loftus and Palmer

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  • Created by: Sam
  • Created on: 30-04-14 19:10

Loftus and Palmer- Context and Aims

  • Eyewitnesses may beleive they are telling the truth when they are in fact not, their memories may be innacurate. 
  • These may be due to leading questions.
  • Leading questions can affect the witnesses ability to judge the speed of vehicles in road traffic accidents.
  • Marshal 1969 found that air force personell gave inaccurate estimates of speed when observing a car travelling at 12 mph.The results ranged from 10-50 mph.
  • With questionin the words used needs to be considered, Filmore 1971 syggested using words such as 'smashed' or 'hit' suggested different rates of movement.

Aims:

  • Their aim was to investigate the accuracy, or inaccuracy of memory. In particular the effect of leading questions on the estimate of speed.
  • The 1st experiment was to see if the estimate by the particicpants would be influenced by a choice of verb.
  • The 2nd experiment was to see if leading questions could bias a response, or alter the memory.
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Loftus and Palmer- Procedure

  • Experiment 1 :
  • 45 students as the sample.
  • shown 7 clips of different traffic accidents.
  • After each clip the participants were asked 'About how fast were the cars going when they ______ each other?' The blank was filled with, hit,smashed,collided, bumped, contacted.
  • Experiment 2:
  • 150 students as the sample. Split in to 3 groups.
  • Part 1 : particpants were shown a 4 second film of a multiple car crash and then asked a set of questions including the critical question about speed.
    • Group 1: 'How fast were the cars going when they smashed into eachother'
    • Group 2: 'How fast were the cars going when they hit eachother'
    • Group 3: Contol group was not asked a question.
  • Part 2: 1 week later the particpants were asked to return and were asked more questions. The critical question was 'Did you see any broken glass? There was no broken glass.
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Loftus and Palmer- Findings

Experiment 1:

  • For the 5 groups, the mean speed scores were calculated. The group given the word smashed estimated the highest speed- 40.8 mph. The group given the word contacted gave the lowest speed, 31.8 mph. (smashed, collided, bumped, hit, contacted)

Experiment 2:

  • Part 1: Participants gave highest speed estimated for smashed, like experiment 1.
  • Part 2: Participants given the word smashed were over twice as likely to report broken glass than the word hit. Even less for the control condition.
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Loftus and Palmer- Conclusions

Experiment 1:

The findings indicated that the form of a question can affect a witnesses' answer. They gave 2 reasons for this :

  • Response bias factors- the crtical word creates a bias response.
  • The memory representation is altered- the critical word changes the person's memory.

Experiment 2:

  • Suggests that the effect of leading question is not because of response bias, , but due to the memory representation being altered, as the perception of the seriousness of the accisent was changed as, particpants believed there was broken class when there was not.
  • Carmicheal et al: Verbal labels can causes a shift with the memory. Related to this experiment.  
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Loftus and Palmer- Methodology+ Alternative Eviden

  • D: Lab experiment, control over extraneous variables, deman characteristics. Used a mean score.
  • E: Did not fully get informed consent, but no harm to participants.
  • R: A number of studies have got the same results. Loftus and Zanni 1975.
  • V: Low ecological validity, highly artificial setting, lacks mundane realism, gives demand characteristics.
  • S: American college students, may have better memories than other people, opportunity sample.

Alternative Evidence:

  •  Loftus and Zanni 1975- asked about 'a broken headlight' or 'the broken headlight' 17% said yes to the rather than 7 % to a.
  • Buckout 1980 showed a purse being stolen on TV, later viewers were shown a identity parade and asked to phone in their answer, only 14% got it right after 2000 viewers.
  • Loftus and Pickrell 1995- showed false memories can be created, interviewed people about childhood events, mentioning a close relative had said another particpant had gotten lost in a shopping mall, about 20% came to believe the false memories.                         
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