Loftus and Palmer (1974)

Loftus and Palmer (1974)

1. Aim

   • To investigate whether leading questions would influence the estimates of the speed of a vehicle recalled by eyewitnesses

2. Procedure

   • experiment 1
     • 45 participants shows 7 video clips and asked to judge speed of the car
     • given a questionnaire and told to give an account of what they had witnessed and to answer a series of specific questions
     • For nine participants, asked 'how fast was the car going when it hit..?'
       • others asked 'smashed', 'bumped', 'contacted' and 'collided'
   • experiment 2
     • sample of 150 participants shown one-minute film of a multiple-car collision and asked to answer a questionnaire description of film
     • Participants spilt into three groups of 50: 'smashed'- 'hit' - no question on speed
     • participants returned one week later and answered ten questions
       • 'Did you see any broken glass?'

3. Results

   • experiment 1
     • smashed- 40.8mph estimate
     • collided- 39.3mph estimate
     • bumped- 38.1mph estimate
     • hit- 34mph estimate
     • contacted- 31.8mph
   • experiment 2
     • yes- smashed (16) - hit (7)- None (6)
       • smashed condition did report seeing broken glass (32%)
       • hit condition- 14%
     • no- smashed (34)- hit (43)- None (44)

4. Conclusions

   • experiment 1
     • results due to one or two factors:
       • verb used altered participants memory of the film
       • participants did not know the answer so relied on the verb to make their judgement
   • experiment 2
     • Leading questions do have an influence on eyewitness testimony. They imply a specific response and may alter witness memory of an incident