Eyewitness testimony (pack 4) Flashcards
between 1989 and 2016 how many exonerations have occurred?
343
how many, in percent, of the 343 exonerations, involved eyewitness misidentification
71%
what did HUFF (1987) conclude about EWT and wrongful convictions?
300 out of 500 were due to false EWT
How does schema theory apply to EWT?
when eyewitnesses encode and store their memory of a crime, they are storing it in a a way that makes sense to them and can be influenced by schemas
what is post event information?
any information that arrives after the event that may affect or distort an eye-witness memory of what happened
what is the effect of post event information on recall?
reduces the reliability of the testimony that they give as it will impact on the storage and retrieval of their memories of the crime
what are leading questions?
questions that are phrased in a way to suggest a particular answer is desired
what two types of information does Loftus and Palmer argue that eyewitness memories are constructed off of?
what the witness perceived happening at the time of the event
the information which the witness receives after the event
What was the aim of Loftus and Palmers studies?
explore how information provided after an event, in the form of leading questions, might affect peoples memories
some of the procedure for Loftus and Palmers first study?
45 students from university of Washington
shown 7 videos of car crashes, ranging from 4 to 30 seconds
after each of the 7 videos, ppts were given a standardised questionnaire asking them to give an account of what they have just seen
CRITICAL QUESTION:
how fast were the cars going when they…… into each other
VERBS:
smashed, collided, bumped, hit and contacted
Results from Loftus and Palmer first experiment?
smashed- 40.8 MP/H
contacted- 31.8 MP/H
conclusion of Loftus and Palmer first experiment?
found that the change of one verb in the critical question could significantly affect the participants estimate of how fast the car was going
what two things did Loftus and Palmer conclude were the reasons for the results in the first study?
- distortion of memory- because it was reconstructed
OR - response-bias- couldn’t remember speeds and therefore tried to adjust their answer to fit with expectations
what was the aim of the second study done by Loftus and Palmer?
aimed to show more conclusively that information provided after an event is capable of distorting memories
procedure of second study done by Loftus and Palmer?
150 students from university of Washington
shown a short film of a multiple car crash lasting one minute
then split into 3 conditions and given a questionnaire that included:
1st group- “how fast were the cars going when they smashed into each other”
2nd group- “how fast were the cars going when they hit each other”
the final group were a control and were not asked about the speed of the car
ppt then came back a week later and asked questions
CRITICAL QUESTION WAS:
“did you see any broken glass” YES/NO
results of Loftus and Palmers second study?
mean speed estimates of the cars when asked how fast they had “smashed” was significantly higher (10.5 mph) compared to “hit” each other (8mph)
broken glass question
yes SMASHED- 16
yes HIT- 7
conclusion for Loftus and palmer second study?
memory is actually reconstructed by post event information
Two overall conclusions from both of Loftus and Palmers studies?
eyewitnesses to car crashes are not very good at estimating the speeds of the vehicles involved
eyewitness testimony is unreliable
Three strengths of Loftus and Palmers studies?
high validity, as there was always high degree of control over the confounding variables- lab based
it has real life applications- the devlin report recommended trial judges be required to instruct juries that it is not safe to rely an entire verdict on EWT
The study is easy to replicate, this is because of the lab experiment which was very standardised
three weaknesses of Loftus and Palmers study?
low ecological validity- does not tell us how we can apply this to real life
low generalisability as they are all students and do not represent the general population
demand characteristics
what does the Yerkes-Dodson Law propose?
an increase in arousal improves performance on any given task but only up to a point
once arousal has passed critical level called optimum point, performance tends to decline.
too stressed to perform well
How does the Yerkes Dodson law apply to EWT?
amount of attention paid to an event
high levels of arousal reduce the effectiveness of the attention paid to the event and memory is negatively influenced
What does the catastrophe theory develop from the Yerkes Dodson law?
it includes the concept of anxiety
what does the catastrophe theory propose?
sometimes alongside physiological arousal, feelings of anxiety become so intense that a sudden catastrophic drop off in cognitive performance occurs