Transcript EWT

EWT
http://www.youtube.com/watch?v=h
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What it is?
• Eyewitness testimony is the memory of an
incident or event from someone who was
actually there at the time.
• Last lesson Friday pupils to wear mufti.
Exam board
Eyewitness testimony (EWT). Factors affecting
the accuracy of EWT, including misleading
information, anxiety, age of witness.
Loftus
Watch the video of Loftus in Scotland.
What did she find: That we can influence the
memory of EW by the language we use.
Watch second Video.
So we can see that misleading questioning can lead
inaccurate recall (memory).
Study of misleading Information
Loftus and Palmer (1974)
Participants watch a video of a car accident.
The they are asked the question to estimate the
speed.
One group is asked “ How fast were the cars
going when they connected” Guess: 31.8
The other “How fast were they going when they
smashed into each other” Guess: 41.8
These results showed that dependent on how
the question was asked effected the answer.
It was a lab experiment and so not real life and a
traumatic event may give better memory.
The effect of leading questions
Loftus & Palmer (1974)
The aim of this study was to investigate the effect of leading verbs on eye witness accounts of a car
crash. All participants watched a film in which two cars crashed in to each other. They were then
randomly allocated to one of five groups and asked to answer some questions about the film. Each
group had one question that differed slightly over the five conditions of the experiment,
“About how fast were the cars going when they collided with each other?”
(The important verb in the question was changed to either contacted, collided, smashed, hit or
bumped.)
In the ‘smashed’ condition participants gave a significantly higher speed estimate (40.8 mph)
compared with the contacted, collided, hit and bumped conditions (31.8, 34.2, 38.1 and 39.3
mph respectively). This showed that the type of question an eyewitness is asked can have a
distorting effect on their memory of an incident. In this case the verb used in the question led
participants into making a different type of speed estimate.
Loftus & Palmer followed also wanted to investigate just how widely the type of questioning
asked could affect participants’ memories of an incident. They followed their initial study with
a second one in which participants were asked the same leading questions again (this time only
hit and smashed were used, and there was also a control condition with no speed related
question) but were also asked whether or not they had seen any broken glass.
“Was there any broken glass at the scene?”
47% of participants in the ‘smashed’ condition reported seeing broken glass compared with
16% in the ‘hit’ condition and 13.5% in the control condition. There had in fact been no broken
glass in the film scene, but participants’ memories were again led into incorrect recall by the
simple verb they were asked. This shows that an eyewitness can be led into providing incorrect
recall of events by the type of questions asked related to the event.
As this was a laboratory experiment Loftus & Palmer were able to establish an extremely
strong causal link between their independent variable (the verb used) and their dependent
variable (the answers participants gave to the questions), and could be relatively certain that
most if not all extraneous variables were controlled for. However laboratory experiments lack
ecological validity, and this particular study does not fairly represent events in real life as a real
life incident would probably be witnessed directly and without warning, and not on a film clip in
a comfortable laboratory.
The participants used in the study were all American university students which means that the
results lack population validity outside that of American university students, in other words they
cannot be generalised to the majority of people in the world.
The effect of misleading information
Misleading information, also known as after the fact information, can change the memory of an eyewitness by
providing information that becomes incorporated in to the memory of the event even though it was not present at the
time of the event.
Loftus (1975)
Loftus demonstrated the power of misleading information in a laboratory experiment in which participants were shown
a film clip of a car accident. After watching the film participants were asked either, “How fast was the white sports car
going when it passed the barn while traveling along the country road?” (the barn condition) or “How fast was the white
sports car going while traveling along the country road?” (the control condition).
“Did you see a barn?”
Even though there was no barn in the film clip, over 17% of participants in the barn condition claimed one week later
that they had seen a barn compared with only 3% in the control condition. The simple question about how far the car
was travelling when it passed the barn was enough to add a barn to memories of 17% of the participants in the study. It
is not hard therefore to see how a question that adds new information may change the memory of a witness to a
crime!
As with all laboratory experiments, there was good control of extraneous variables which allows a causal link to be
established between the question type and the answers participants gave to the questions. The study was however low
in ecological validity as the task was unrepresentative of everyday events (i.e. a film rather than a real life incident), and
it was low in population validity as the participants were all American college students.
“Did you see a barn?”
Even though there was no barn in the film clip, over 17% of participants in the
barn condition claimed one week later that they had seen a barn compared
with only 3% in the control condition. The simple question about how far the
car was travelling when it passed the barn was enough to add a barn to
memories of 17% of the participants in the study. It is not hard therefore to
see how a question that adds new information may change the memory of a
witness to a crime!
As with all laboratory experiments, there was good control of extraneous
variables which allows a causal link to be established between the question
type and the answers participants gave to the questions. The study was
however low in ecological validity as the task was unrepresentative of
everyday events (i.e. a film rather than a real life incident), and it was low in
population validity as the participants were all American college students.
Part 2 of video
What about blatantly incorrect
information?
When misleading information is provided that is blatantly incorrect,
witnesses are generally more resistant to being misled and tend to
stick to the events they remember witnessing. Loftus (1975) showed
participants a set of slides of a handbag robbery. Immediately after
seeing the slides participants were asked what the colour of the
handbag was, with the result that 98% correctly answered that it was a
red handbag. Participants then read an account given by a professor of
psychology who witnessed the incident - one version of the witness
account had many minor incorrect facts and the another version stated
that a brown handbag had been stolen. Almost all of the participants
who read the brown handbag account resisted the incorrect
information and stuck to their memories of a red handbag.
A Level exam tips
Answering a 12 mark question (PSYA1 AQA A specification)
Outline and evaluate research into the effects of misleading
information on eyewitness testimony.
6 AO1 marks - describe the research. This page details a study by
Loftus & Palmer (1974) into leading questions, a study by Loftus (1975)
into misleading after the fact information, and a study by Loftus
91975) into blatantly incorrect information.
6AO2 marks come from evaluating the research. Discuss the studies in
terms of them being laboratory experiments that have the strengths of
control of extraneous variables and good causal inference, but the
weaknesses of low ecological validity and low population validity.
Explain why these are strengths or weaknesses for the studies.
Essay
Describe One study of the effects of misleading
information on eyewitness testimony. (6)
Explain one problem with the validity of the
study described in the above question (3)
The effect of anxiety on eyewitness
testimony
How does a stressful situation, such as the
presence of a weapon, affect the accuracy of
eyewitness memory?
Is there a difference between laboratory and
real life studies of anxiety in EWT?
What do you think! Discussion
Anxiety and cognitive performance
•
Inverted U theory (Deffenbacher, 1983)
Inverted U theory states that at low levels of anxiety cognitive performance (in this case
memory accuracy) will be at a relatively low level, but as anxiety increases then so does
cognitive performance until it reaches an optimal level after which any further increase in
anxiety level leads to a rapid drop in cognitive performance.
You may recognise this from
sports as it is the theory for
arousal at an event. That is
your performance dips if over
anxious.
If we apply this theory to eyewitness testimony
we can predict that stressful incidents, such as
being a victim or witness to a crime, will lead to
witnesses having relatively inaccurate memories
of the event as their anxiety levels at the time
would have been above the optimal level.
Peters (1988)
Peters (1988) found that participants who
received an inoculation showed impaired
eyewitness identification and recollection of the
appearance of the nurse who gave the injection,
in comparison to a researcher with whom they
interacted for a similar length of time a few
minutes after the receiving the injection. The
effect was stronger for participants who showed
greater physiological activation whilst waiting
for their inoculation.
Weapon focus
Participants in this study were left in a waiting area outside a laboratory whilst waiting
for the “real” study to start. While they were waiting one of two situations occurred.
In the first situation they overheard a discussion in the laboratory about equipment
failure, followed by a man leaving the laboratory holding a pen and with grease on his
hands. In the second situation participants overheard a heated discussion in the
laboratory with the sound of breaking glass and crashing chairs, followed by a man
leaving the laboratory carrying a paper knife covered in blood. The participants were
later asked to identify the man from a set of 50 photographs with the result that 49%
correctly identified the man holding the pen, but only 33% could identify the man
with the blood stained knife.
Loftus argued that participants were less able to correctly recall the man with the
knife because they had their attention absorbed by the knife (presumably because it
was potentially a source of danger to them), and so were distracted from the
appearance of the man holding it. This has become known as weapon focus and
explains how witnesses to violent crimes may accurately recall central details (e.g. the
type of weapon and what was done with it), but may be less accurate at recalling
periphery details such as the appearance or clothing of a criminal.
Yuille & Cutshall (1986)
Yuille & Cutshall interviewed 13 witnesses to a real life
shooting in which a storeowner in America was injured
and the thief was shot dead. Some of the witnesses had
been very close to the incident whist others had viewed it
from a distance away. The researchers found that the
witnesses closest to the event gave the most detail, that
all of the witnesses were able to give accurate accounts
several months later, that they were seemingly
unaffected by misleading questions, and that the
witnesses that had been the most distressed at the time
of the incident actually gave the most accurate testimony
several months later.
Christianson & Hubinette (1993)
110 witnesses of 22 real life bank robberies were interviewed some
time after the robberies. Some of the witnesses had been onlookers or
customers in the bank, and others were bank employees who had
been directly threatened or subjected to violence during the robberies.
The findings were that the victims were surprisingly accurate in their
recall of the robbers’ clothing and behaviour, and that the accuracy
was still evident 15 months later.
The results of these studies are surprising as they are completely
opposite to those that inverted U theory and weapon focus would
predict. The witnesses were neither so distressed that their cognitive
Which
onewas
dotheir
you attention
think is overly absorbed by
performance was very
low, nor
the presence of a weapon. Butcorrect?
as it was an uncontrolled study then it
could be that the witnesses had discussed the shooting so often, been
interviewed so many times, and even read about the event in the
newspapers that their memories may not be entirely their own.
The difference between laboratory
and real world research into anxiety
and eyewitness testimony
READ
Real world research into eyewitness testimony has a valuable advantage over
laboratory research as it has very high ecological validity. In laboratory studies,
participants are exposed to often unrealistic scenarios presented in an unrealistic way,
and to a certain extent there are demand characteristics as they are expecting to be
asked about the event they are shown. Real world events are sudden, unexpected,
have high levels of emotion and stress involved, and provide the only real way to test
how accurately witnesses recall events; however they are also uncontrolled and it is
impossible to account for how witnesses may discuss the event with one another, are
interviewed by authorities, and what they read before the researchers get the chance
to interview them. Both laboratory and real life studies are therefore important, but it
is very interesting how the methods provide contrasting results.
A Level exam tips
Answering a 12 mark question (PSYA1 AQA A specification)
Outline and evaluate research into the effect of anxiety on
EWT
AO1 marks would come from a description of relevant
research studies. Choosing 3 studies, perhaps 1 lab study and
2 real life ones, and describing them in simple paragraphs
would be sufficient.
AO2 marks would then come from evaluating the studies and
explaining what the evaluation means for the validity of the
research. Focus on control of extraneous variables, cause and
effect, ecological validity, and population validity or
generalisabilty.
Question
• Describe one study of the effects of
misleading information on Eyewitness
testimony? (6)
• Outline and evaluate research on the effect of
misleading information on eyewitness
testimony (12)
• http://www.wimp.com/psychologyexperiment
/
The effect of age on eyewitness
testimony
Children are rubbish –they want to please. They want to answer
the authority figure.
A little more scientific: Kent & Yuille (1987)
Kent & Yuille asked children to identify from a set of photographs a person they had seen earlier. They
found that 9 year old children were far more likely than 14 year olds to identify someone from the
photo set even when the target person was not present - in other words younger children were less
likely to say that the person they had seen earlier was not present in the photo set. This followed earlier
research that showed children as young as 5 were as able to correctly identify people they had seen
earlier, and so it is not a problem with children’s memories that causes them to identify wrong people,
but it is more likely that they feel less able to admit to an adult that they cannot do the task and so they
just pick any photo when the target one is not there.
Research into the accuracy of children as eyewitnesses by Geiselman & Padilla (1988) found that
children were far less accurate when reporting events of a filmed bank robbery than adults, however
other research has failed to find much of a difference between adults and children, especially when free
recall rather than structured interview is used (e.g. Cassel et al, 1996).
Factors affecting the accuracy of
children’s memories
1. Encoding: semantic for LT – not enough
experience.
2. Storage: Children susceptible to decline
3. Retrieval: Children more susceptible to
leading questions.
Research
Roberts and Lamb - they analysed 161 police interviews with
children regarding allegations of abuse.
In 68 / 161 of the interviews the interviewer misinterpreted
“in private” as “in the privates” and in 2/3 of these cases this
remained uncorrected by the children.
Therefore, this research would suggest that people of a young
age do not have accurate eye witness testimony.
Davies - found that differences between child and adult
interviews were overstated and that children can provide
very valuable eye witness testimony as long as care is taken
during the interviewing procedure.
Therefore, this research would suggest that people of a young
age do have accurate eye witness testimony.
Old Age
• Cohen and Faulkner - they showed 70 year olds and 35 year olds a film of
a kidnapping then presented them with misleading details before asking
them to recall what happened in the film.
• They found that the 70 years olds were more likely to be mislead than the
35 years olds.
• Therefore, this research would suggest that people of an old age do not
have accurate eye witness testimony.
• Coxon and Valentine - they asked children (aged 8 ), young adults (aged
17) and older adults (aged 70) questions containing misleading
information after they had watched a video. They then asked a further 20
specific questions to assess whether they had accepted the misleading
information or not.
• They found that the older adults were less suggestible and were the only
age group not to show a statistically significant misinformation effect.
• Therefore, this research would suggest that people of an old age do have
accurate eye witness testimony.
So.
• Strength / Weakness - most of the research is lab based meaning it is
replicable and scientific but is lacking in ecological validity.
• Strength / Weakness - research that is in the form of
naturally occurring phenomena (Roberts and Lamb) has good ecological
validity but is not scientific or replicable as variables were not highly
controlled and because it is not artificial. It would also be unethical to test
eye witness testimony when a real sensitive subject is being discussed.
• Strength / Weakness - the results could be due to a number of factors
such as: young people may be more used to memory tests or older adults
have poorer health leading to memory impairment.
• Weakness - the research findings are inconclusive.
• Weakness - the factors given by researchers, such as the ones stated, are
only assumptions with no scientific evidence.
• Weakness - the research over exaggerates how bad memory is. This could
be due to the fact that it is being studied in lab conditions and only the
short term effects of memory and eye witness testimony are being taken
into account.
Questions
The graph shows the relationship
between anxiety and recall. What can
you conclude from the graph? (4)
Describe what research has shown about the effect of the age of a
witness on the accuracy of eyewitness testimony. (6)
Cognitive Interview
Rationale behind the cognitive interview
As we have seen from research into the effects of misleading
information, leading questions and age on eyewitness
testimony, the memories eyewitnesses have for a crucial
event can be extremely inaccurate. This seems to be because
selecting information to store in long term memory is driven
by schemas, encoding is based on meaning and is organised
into schemas, and recall is reconstructive based on schemas
that guide the eyewitness to recreating the event based on
what they would expect to happen rather than what actually
happened. The cognitive interview provides authorities with
an interview technique that is less likely to activate schemas
than a standard interview.
Link
Gieselman et al (1985)
The cognitive interview has four main techniques:
1. Report everything. Witnesses may omit details they feel are irrelevant,
especially if they do not fit into their existing schemas for that type of event.
Encouraging them to report every detail, no matter how small, can increase
witness accuracy.
2. Reinstate the context at the time of the event. Encouraging witnesses to
recall how they felt, the weather, smells, time of day etc helps put the person
back in time to the incident and may improve recall accuracy.
3. Change the order in which the event is recalled. Recalling events in reverse
order, or from the middle and working backwards and forwards in time, can
interrupt schema activation, make it harder for the witness to reconstruct a
story that makes sense, and improve eyewitness accuracy.
4. Change perspective. Trying to adopt the viewpoint of a different witness,
e.g. a prominent character in the incident, can encourage recall of events that
may otherwise be omitted.
Research
Geiselman et al (1985)
Geiselman et al compared their cognitive interview with a
standard interview technique on 51 volunteer participants
from a wide demographic background. Participants watched
two films of violent crimes and 48 hours later were
interviewed by trained police officers using either a standard
interview or a cognitive interview. The results showed a
significant increase in the number of correct items recalled
using the cognitive interview, and a small decrease in the
number of confabulated items (items of descriptions made up
by participants to fit the story). This research was, of course,
lacking in ecological validity as participants watched filmed
incidents.
Research 2
Fisher et al (1989)
This was a study of real life cognitive interview
performance. The researchers trained police
detectives in Florida in the use of the cognitive
interview, and compared their interview
performable before and after training. After
training, the detectives gained as much as 47%
more useful information from witnesses to real
crimes compared to when they had been using
standard interview techniques.
Other research
Bekerian & Dennet (1993) reviewed 27 studies into
the effectiveness of the cognitive interview
schedule and found that the cognitive interview
provided more accurate information than other
interview techniques. Holliday (2003) showed
children aged 5 to 9 a video of a child’s birthday
party and interviewed them the next day using both
cognitive and standard interview methods. They
found that the cognitive interview yielded more
correct details about the video than the standard
interview, and so showed that it can also be very
useful when interviewing children.
A Level exam tips
Answering a 12 mark question (PSYA1 AQA A specification)
Outline and evaluate the cognitive interview.
6 AO1 marks can be gained by introducing the cognitive interview as a tool to
reduce schema activation and improve eyewitness accuracy, followed by an
explanation of the 4 main techniques and examples of one or two of them.
Some questions will be based on a scenario and so it is important to give
examples that relate to that scenario.
6 AO2 marks will come from evaluating the effectiveness of the cognitive
interview in comparison to a standard interview technique. Summarising and
evaluating the research by Geiselman et al (1985), Fisher et al (1989),
Bekerian & Dennet (1993), and Holliday (2003) will usually gain full marks.