loftus and palmer

• background of loftus and palmer

  research into memory:

  • psychologists shown memories don't just record what happens- not accurate. this could have profound consequences in eyewitness testimony.

  leading questions:

  • certain q's are phrased in way that leads person to give a particular answer.

  estimating speed:

  • research shown ppl very inaccurate when estimating speed, suggesting may be easy to influence the answers ppl give to such numerical q's.
• aims of loftus and palmer

  1. 1st experiment= investigate accuracy of memory & in particular effect of leading questions on what ppl remember
  2. 2nd experiment= see if leading question changed a persons subsequent memory of the event they witnessed
• method of loftus and palmer

  • both= lab experiments
  • both= independent measures design
  • 1st= snapshot study
  • 2nd= longitudinal (over 1 week)
• sample of loftus and palmer

  1st experiment:

  • 45 american college students
  • divided into 5 ppt groups each receiving 1 condition of the iv
  • dv= estimate of speed

  2nd experiment:

  • 150 american college students
  • divided into 3 groups
  • was 2 lvls of iv and a control group
  • dv= whether ppts saw broken glas
• materials/ apparatus in loftus and palmer

  experiment 1:

  • ppts shown 7 brief film clips of car accidents
  • after each clip asked to fill in questionnaire

  experiment 2:

  • ppts shown 1 min film clip containing 4 second multiple car accident
• procedure of loftus and palmer- experiment 1

  1. asked to describe the accident, given the series questions abt film clips including the critical question- 'how fast were the cars going when they [insert verb] into each other?
  2. ppts were in 1 of 5 diff verb conditions:

  • g1= 'hit'
  • g2= 'contacted'
  • g3= 'smashed'
  • g4= 'bumped'
  • g5= 'collided'

  3. ppts were asked (qnaire) to estimate the cars speed in mph
• procedure of loftus and palmer- experiment 2

  1. part 1- ppts asked to describe the accident, then given questions abt film clips including critical question about speed 'how fast were the cars going when they [insert verb] into each other'
  2. there were 3 groups of ppts

  • g1= 'smashed'
  • g2= 'hit'
  • g3= control group- there was no question

  3. part 2- ppts asked to return to lab a week later

  4. they were asked some further questions about the film clips they saw last week one of the q's was 'did you see any broken glass' (there was no broken glass)
• results of loftus and palmer- experiment 1

  experiment 1:

  • mean speed estimates were faster with the verb 'smashed' (40.8mph) than with verb 'contacted' (31.8mph)
  • the mean speed estimates for the other groups were: collided- 39.3mph, bumped 38.1mph and hit 34.0mph
  • ppts were not able to accurately able to estimate speed. in 4 of the films the accident took place at the following speeds: 20mph, 30mph and 40mph- yet ppts mean estimates for all of these was between 36-40mph
• results of loftus and palmer- experiment 2

  experiment 2:

  • mean speed estimate were faster for those who had the verb 'smashed' (10.46mph) than those with verb 'hit' (8.0mph)
  • more ppts who had the verb 'smashed' reported seeing broken glass (16 out of 50 ppts) than other ppts.
  • in the other groups 7 out of 50 ppts with the verb 'hit' reported seeing broken glass & 6 out of 50 ppts in control group reported broken glass
  • overall most ppts correctly reported seeing no broken glass (121/150)
• conclusions of loftus and palmer

  experiment 1: the way a question is asked can influence the answer given

  experiment 2: such questions influence the memory that is stored rather than just biasing a persons responce

  this shows that 2 types of info make up our memory of a complex event. firstly the info from our perception of the event and secondly the info recived after the event
• research methods- loftus and palmer: strengths

  • controlled lab experi, contrived techniques used to test eyewitness testimony

  strengths:

  • controlled conditions of lab means potential ev's can be controlled
  • eg. eyewitness testimony tested in real life persons estimate of speed may be affected by where they were standing
  • it can be made sure in lab that each ppt witnesses accident from same position -> this would have threatened the internal validity of the study
• research methods- loftus and palmer: weaknesses

  weaknesses:

  • fact not a real accident means ppts lacked emotional involvement & research shown ppl in real accidents are likely to remember more.
• sampling bias of loftus and palmer - strength

  • american students

  strength:

  • such ppts easy for researchers to obtain- ppts are expected to take part in research studies at uni and may even be offered course credits--doesn't mean that they make good ppts tho
• sampling bias of loftus and palmer- weakness

  • american students

  weakness:

  • students have unique characteristics- more intelligence than average person and tend to have better memories therefore may be less likely to be affected by leading q's
• ethnocentrism- loftus and palmer

  • america= individualist culture
  • this might affect their willingness to be influenced by leading q's
  • ppl in collectivist cultures may be more influenced abt what other ppl say
• type of data- loftus and palmer

  • quantitative- estimates of speed & yes/no answers
  • enabling clear results in graphs producing simple conclusions
  • however such data gives no explanation to why they estimated speed they did
• reliability of loftus and palmer

  • strength of quantitative data= straight forward to assess reliability of measurements made
  • u could ask same ppts repeat task and get same result each time
• ethical considerations of loftus and palmer

  • l&p did not gain fully informed consent from ppts
  • if ppts were aware of the aims of study this would've affected their behaviour- more careful in responses given as know q's are leading
  • however can be justified as they were not psychologically or physically harmed and unlikely that knowing the aims of the study would've led them to not taking part.