Loftus & Palmer Flashcards
Aim
test reliability of/investigate effect of leading Qs on eye witness testimonies
Research Method
Lab experiment:
+ : high control lvls
- : demand characteristics BUT tried to minimise this using independent measures
Sample
- 1: 45 students divided into 5 groups
- 2: 150 students divided into 3 groups
- ^ volunteers/self-selected/in American uni ^
Variables
- IV: verb used
-
DV: 1) speed estimate
2) whether ppt saw glass
Procedure Study 1
- watched clips of car accidents
- wrote account of what they saw + answer questionnaire
- each identical except for one critical Q : “about how fast were the cars going when they smashed/collided/bumped/hit/contacted each other
Procedure Study 2
- watched 1 min film which showed 4s multiple car accidents
- after, divided into 3 groups : how fast were cars going when they smashed or hit each other or CONTROL = ✕ Q ab speed asked
1 week later
- ppts from all 3 groups returned + were asked more Qs
- critical Q: did you see any broken glass?
- there was none
Results Study 1
verb > approx mean speed estimate (mph)
- smashed > 41
- collided > 39
- bumped > 38
- hit > 34
- contacted > 32
RS1) 4 staged films where speeds were accurately measured
film - actual speed (mph) - mean estimate (mph)
- 1 - 20 - 37.7
- 2 - 30 - 36.2
- 3 - 40 - 39.7
Results Study 2
- smashed: 16 yes, 34 no
- hit: 7 yes, 43 no
- control: 6 yes, 44 no
RS2) more detail
- x2 in smashed said they saw glass compared to hit/control
- no real diff between hit/control > some ppts in both had inaccurate recall
- majority of ppts had accurate recall ; no broken glass
Conclusions Study 1
- question phrasing influenced ppts speed estimates
- ppts estimated car = much faster when ‘smashed’ but not ‘contacted’
- ppl not good at judging vehicle speed
- Response Bias: critical word makes ppl think they should act certain way (demand characteristics)
- Altered Memory: critical word changes person’s memory so they see accident diffly
Conclusions Study 2
- leading Q altered ppts’ memory of events
- the way q is asked can influence answer given (more ppts in smashed said yes to glass compared to hit/control)
- L + P suggests that 2 kinds of info go into person’s memory for event
1) person’s own perception at time of event
2) info supplied after event (eg. leading Q)
Links to cognitive area ;
- internal mental processes eg. memory
-
computer analogy; mind processes + manipulates info
> input (critical verb) –> manipulated how info was processed –> creates diff output (speed estimates) - schema: stores all info, constantly updated, used to interpret new experiences
- complex occurence: mind may have reconstructed memory ; of critical word which made ppl view accident diffly
- scientific, high control lvls: lab, sandardized, same Qs except crtitical Q
Types of data
-
quantitative data: speed estimate
✓ easily compare/analyse data
✕ missing reasoning/human insight
Reliability
- high ; controls = standardised procedure ~ replicable
- controls = questionnaire, film/clips
