Classic research

• What is the classic research of the cognitive approach?

  Loftus & Palmer

  Interaction between language & memory
• Loftus & Palmer - Aim of experiment 1

  To investigate the effect of leading questions on the estimate of speed.
• Loftus & Palmer - methodology

  Lab experiment

  Independent groups design
• Loftus & Palmer - experiment 1 procedures 


  45 American University students split into 5 groups.

  All shown the same 7 short video clips of car accidents.

  Filled in a questionnaire that included the critical question ‘about how fast were the cars going when they …. each other?’ The 5 verbs were smashed, hit, collided, bumped, contacted.

  Speed estimates recorded in MPH.
• Loftus & Palmer - experiment 1 findings 


  Mean estimate calculated for each experimental group:

  Smashed - 40.8

  Collided - 39.3

  Bumped - 38.1

  Hit - 34.0

  Contacted - 31.8
• Loftus & Palmer - experiment 1 conclusions 


  Leading questions can affect a witness’ answer.

  Two explanations for this:

  Response bias

  Memory altered
• Loftus & Palmer - experiment 2 aim


  To see if leading questions biased responses or altered memory.
• Loftus & Palmer - experiment 2 procedures 


  150 American University students split into 3 groups of 50.

  Shown a short film that showed a multi-vehicle car accident.

  Asked a series of questions including the critical question ‘about how fast were the cars going when they ….. each other?’

  One week later, they were asked further questions, including the critical question ‘did you see any broken glass?’ There was no broken glass in the film.
• Loftus & Palmer - experiment 2 findings

  Yes:

  Smashed 16

  Hit 7

  Control 6

  No:

  Smashed 34

  Hit 43

  Control 44
• Loftus & Palmer - experiment 2 conclusions 


  Leading questions can alter memory
• Methodological strengths of Loftus & Palmer’s research

  Lab - controlled environment means less impact of extraneous variables, easier to establish cause & effect.

  Independent groups - no order affects compared to repeated measures, only one condition so less likely to guess aim of study and exhibit demand characteristics.
• Methodological weaknesses of Loftus & Palmer‘s research

  Individual differences may impact results

  Artificial / contrived task - lacks ecological validity

  Limited sample - only American students from one university used - lacks population validity
• Ethical issues of Loftus & Palmer’s research

  Deception - not told aim of study (informed consent)

  Right to withdraw - Loftus was a professor at the student‘s university so may have felt obliged to take part
• Ethical strengths of Loftus & Palmer’s research 


  Video of car crash caused less harm than a real one
• Social implications of Loftus & Palmer’s research


  Police given other methods of questioning to avoid leading questions

  Leading questions can be used to manipulate

  Shows that other evidence should be used alongside EWT