Loftus and Palmer (1974) Eyewitness Testimony Flashcards
(25 cards)
area
cognitive
assumptions
Assumption 1 – Behaviour is the result of internal mental processes, e.g. memory, attention and thinking.
Assumption 2 – Behaviour is the result of our mind working like a computer – information is input, stored and retrieved.
background summary
Schemas - simplified, generalised mental representations of everything an individual understands by a type of object or event based on their past experiences. Each mental schema contains the STEREOTYPES and EXPECTATIONS we have acquired during our lives.
Reconstructive memory - Memory does not work like a video recording, meaning that our memories of an event are often incomplete, as we only recall the important points. Reconstructive memory suggests that in the absence of all information, we fill in the gaps to make more sense of what happened.
EWT - an account given by people of an event they have witnessed. For example, they may be required to give a
description at a trial of a robbery or a road accident someone has seen.
Leading questions - A question phrased in a manner that tends to suggest the desired answer, for example in the
Loftus and Palmer’s study, they have used: How fast were the cars going when they smashed into each other?
experiment 1 aim
To investigate whether using different verbs to describe a collision between two cars would affect estimates of the speed.
experiment 2 aim
To investigate whether the different speed estimates found in Experiment 1 were in fact due to distortion in memory.
experiment 1 method
Lab experiment with independent measures design
IV - verb used (smashed, hit, bumped, collided, contacted)
DV – mean estimates of speed
experiment 2 method
Lab experiment with independent measures design
IV – verb used (smashed, hit, control)
DV – Yes/No (Did you see any broken glass?)
experiment 1 sample
45 students (no details of age or gender), Washington Uni, opportunity sample.
experiment 2 sample
150 students (no details of age or gender), Washington University, opportunity sample.
experiment 1 procedure
Participants were shown 7 films of car crashes (ranged from 5-30 seconds), speeds were 20mph, 30mph, 40mph, 40mph.
Questionnaire (with fillers and critical question).
critical question included different verbs in possibly increase severity of crashes (bumped, hit, smashed, collided, contacted).
experiment 2 procedure
Participants were shown a film of a car crash (film lasted less than a minute and the accident itself lasted 4 seconds) Questionnaire (with fillers and critical question – How fast…) 50pps – smashed, 50 – hit, 50 - no qs about speed A week later participants returned and answered further 1- qs including ‘Did you see any broken glass’?
experiment 1 results
Estimations of speed:
Smashed 40.8 mph
Collided 39.3 mph
Bumped 38.1 mph
Hit 34.0 mph
Contacted 31.8 mph
We can see clearly that the more severe sounding the verb, the higher the estimated speed – nearly 10mph difference!!!
experiment 2 results
Number of participants who claimed to see broken glass (although none was present on the video)
Hit 7
Smashed 16
Control 6
experiment 1 conclusions
Response bias – a participant is unclear which speed to estimate so the verb gives them a clue as to whether to estimate a high or low figure OR
Memory distortion – the verb used in the leading question alters a participant’s memory of the crash.
experiment 2 conclusions
The wording of the question distorted their memory of the accident. Two kinds of information go into person’s memory for a complex occurrence: perception of the event and post-event info. These combine to form memory – reconstructive hypothesis.
ethical guidelines broken
- informed consent (hypothesis about leading questions was not revealed to them and filler questions concealed the aim).
- deception (they knew the study was about memory but hypothesis about leading questions was not given to them).
- right to withdraw (as they are young they might have felt obliged to doing the study).
- protection of ps (watching videos of crashes may upset people who has been in a crash before).
ethical guidelines adhered to
- informed consent (they knew the study was about memory so had given some form of consent).
- debrief.
- right to withdraw.
- confidentiality (we only know the university they go to, no other information).
- protection of ps (no gruesome images, less likely to cause harm).
applications
Useful as lawyers and police are warned that leading questions should not be used.
Devlin Report (1976) recommended that the trial judge be required to instruct the jury that it is not safe to convict on a single eyewitness testimony alone except in exceptional circumstances or when there is substantial corroborative evidence.
how does the core study link to the area/ perspective?
[A] Behaviour is the result of mental processes, such as thinking and memory. [L] Loftus & Palmer studied the effect of post-event information (leading questions) on the memory of an event and showed that distortion occurred (increased speed estimates or seeing of broken glass). [E] More people in smashed condition (16) reported seeing broken glass (although there was none on the video) than in hit condition (7).
[A] The mind works like a computer where information is input, stored and retrieved. [L] Videos of a car crash along with leading questions are input and then stored, which results in a retrieval of distorted memory through increased mph speed estimate or misremembering seeing broken glass. [E] Smashed speed estimates higher than contacted, 40.8 and 31.8 respectively.
how does the core study link to the key theme?
Loftus and Palmer asked Washington university students (45 in exp 1 and 150 in exp 2) to watch videos of a car crash and - in exp 1 - estimate the speed in response to a leading question: how fast were the cars going when they hit/smashed/bumped/collided/contacted each other? whereas in exp 2 answer another leading q: Did you see any broken glass? Both experiments demonstrate that memory can be distorted through post-event information, since the harsher the verb used the higher the speed estimates, leading to reconstructive memory. This is when information perceived during an event (witnessing the videos) combines with information provided after the event (the verb in the critical question) to form a merged memory. This shows that EWT is prone to inaccuracy and has been used to suggest that EWT alone should not be enough to convict in a court of law.
ethnocentrism
- Yes, Only American sample – more used to cars compared to tribal or less developed countries.
+ No, Cognitive processes are thought to be linked to brain functioning – species specific behaviour and therefore be universal across culture.
population validity
+ Reasonable sample size, especially in exp 2.
+ The participants were all students. There are several ways in which students might not be representative of the general population. These may include age, higher family income and educational experience – (i.e. they may be used to paying attention and being tested?). Also, students have less driving experience – speed estimates less accurate.
- No information on gender.
reliability
+ Controlled experiment = high replicability. Controls, e.g. videos (same 7 videos and length), questions asked (critical and fillers), location (controlled room and no background noise), seeing accident from same viewpoint.
+ Has been replicated with similar findings (TEST-RETEST!). Both experiments provided evidence that memory of an event can be distorted by information introduced afterwards – supports reliability
+ Use of quantitative data (speed estimates) increases reliability.
internal validity
+ Extraneous variables are controlled i.e. they all saw the accident from the same position (in real life this would not be the case and may affect speed estimates) + filler questions.
+ Independent measures – each participant only took part in one condition: hit, smashed, collided, contacted OR bumped – less demand characteristics, no order effects.
- Participants knew they were in an experiment so may have tried to guess the aim and think they were ‘supposed’ to remember seeing broken glass so did so to fit expectations of the experimenter.
- Independent measures – participant variables, such as naturally better memory etc.
