Download Core studies summary

Core studies summary Loftus & Palmer Eyewitness testimony
also see separate sheets
Aims and context (Put aims of study & background history):
The aim: Was to find out how accurately people remember the details of
a complex event, like an accident. Researchers aimed to find out how
accurate people are in reporting numerical details such as how fast two
vehicles were travelling. Do leading questions affect people’s estimate of
such details? A leading question is one that suggests to the witness what
answer is desired or leads him/her to the desired answer. The aim of this
study was also to investigate how information supplied after an event
influences a witness's memory for that event.
Loftus’ aim was to investigate whether the verbs used in a question
could affect recall of an event. Firstly, whether “the form of a
question (in this case, changes in a single word) can markedly and
systematically affect a witness’s answer to that question”.
Secondly, whether the same question asked with the verb smashed
replaced by hit had consequences for how questions are answered
a week after the original event occurred”.
Context:
Many of the early studies of memory (e.g. Bartlett 1932) demonstrated
how memories are not accurate records of our experiences. It seems
that we try to fit past events into our existing representations of the world,
making the memory more coherent or make more sense for us.
A leading question is one which, by its form or content, suggests to the
witness what answer is desired or leads him to the desired answer. When
investigators are asking questions of eyewitnesses it maybe that the
meaning of certain words may influence our recollection of an event and
as a result it may corrupt our memory.
There is support for the idea that most
people when witness to a complex event,
like a traffic accident are very inaccurate
when reporting numerical details like time,
distance, and speed even if they know they
will be questioned on them (e.g. Marshall
1969). As a result there can be large
variations in the estimates between
witnesses so it seems likely that inaccurate testimony can be influenced
65
by such variables like leading questions.
Marshall did a study where Air Force personnel were questioned about
the speed of a moving car. They knew in advance they would be asked
this and worryingly estimates ranged from 10-50 mph; the car they
watched was only going at 12 mph.
Psychologists like Loftus & Palmer are interested in eye-witness
testimony, as juries are convinced by eye-witness accounts and will tend
to return guilty verdicts when there has been an eyewitness account
presented by the prosecution. Even when the eye-witness has been
discredited juries are still convinced by the information.
Psychological research into memory strongly suggests that there are
many factors which would make eye-witnesses unreliable and the Devlin
Committee (1973) recommended that juries should be instructed that it is
not safe to convict on the basis of eye-witness testimony alone. Eyewitness testimony is unreliable.
Eyewitness memory can be mistaken due to the things that go wrong at
the time of the event itself e.g. poor lighting or extremely high stress or
fright. Memory can be wrong due to things that go wrong after the event
is over. For example, one witness can be exposed to the mistaken
recollection of another witness, or the witness is questioned in a biased
way or the test of memory is unfair in some way and leads the witness to
say the wrong thing.
Filmore (1971) suggests that the words smashed and hit may involve
differential rates of movement. They also lead the listener to assume
different consequences to the impacts to which they are referring, with hit
being perceived as gentler than smashed.
Procedures (What did the Psychologists do to the participants?)
Experiment 1:
 45 students participated in smaller groups of various sizes.
 They were shown safety films of traffic accidents lasting 5-30
seconds.
 After each film they had to fill in a questionnaire about what they
had seen.
66
 They then answered questions about the accident; the critical
question was the one that asked the participants about the speed of
the vehicles involved in the accident.
 9 participants (p’s) were asked “About how fast were the cars going
when they hit each other?” Equal numbers of the remaining p’s
were asked the same question but with the verb changed, so some
groups were asked the question changed to smashed, collided,
bumped, and contacted instead of hit.
 Participant estimates of speed in each group were recorded in miles
per hour.
Experiment 2:
 150 p’s took part in groups of various sizes.
 A film showing a multiple car accident was presented.
 P’s had a questionnaire where they first had to describe what went
on in the film of 1 minute.
 They then had to answer questions about the accident.
 The critical question asked 50 p’s “About how fast were the cars
going when they smashed into each other?”
 Another 50 p’s were asked the same question but with the word hit
supplied instead of smashed.
 The final 50 participants were a ‘control’ group and were not
exposed to any question.
 1 week later p’s returned and were asked a series of questions
about the film they saw the week before.
 The critical question was “Did you seen any broken glass?” they
had to tick off YES or NO.
 This question appeared in a random position with 9 other questions
- there was no broken glass in the accident.
67
Perspective : cognitive
Method: Lab experiment
3 advantages of the methodology: Sample (e.g. representative)
Internal & external validity/internal & external reliability/ethics & any other
issues:
1. A well controlled and operationalised experiment. Age of the
participants, location of study, and use of video (length of films)
were all controlled.
2. The experimental method is reliable as procedures can be
replicated and if the same results are found over time we have
confidence in the findings. Later studies have found similar findings
e.g. Loftus & Zanni (1975) found leading questions affect recall.
More people answered ’yes’ to the question “Did you see THE
broken headlight” as opposed to “Did you see A broken headlight?”
3. The information the p’s were asked to recall was meaningful &
would be likely to occur in real life so results are representative of
the demands of our everyday memory, so findings could be
generalised to real life.
4. Cause and effect relationship can be established between IV and
DV as the variables are all controlled (e.g. See 1 above) No other
research method can do this directly.
3 disadvantages of this methodology: Sample bias/validity – internal &
external/reliability internal & external/ethics/gender bias/cultural bias &
any other issues:
1. Students were used in each part of the study, students may not be
representative of the general population and it is hard to generalise
results from this study to other types of people.
2. The experiment was based in a laboratory which is an artificial
environment; the students may have reacted to demand
characteristics - clues in the study for how to behave. This would
produce invalid results. It could also lack internal validity because of
demand characteristics.
3. Ethics - the p’s were deceived about the purpose of the experiment.
68
This also means they had no informed consent and didn’t know
aims of the study.
4. Research lacks mundane realism (task in the study is not like real
life task/event) as there are differences between observing an event
like a car crash in real life and observing one on a TV. screen, if we
actually witness a car crash we are emotionally affected by it, this
could affect your memory in a different way from the film shown by
Loftus & Palmer.
Findings and conclusions of the study:
Experiment 1:
 P’s were not very good at estimating the speed of a vehicle.
 Estimates of the speed of the vehicle averaged 40.8mph if the p’s
heard the words smashed, 39.3 if the p’s heard the word collided in
the first experiment and so on. If they heard contacted, the estimate
was only 31.8 mph.
 Participants estimated that the vehicles had been travelling fastest
when the verb ‘smashed’ was used.
 Participants estimated that the vehicles had been travelling slowest
when the verb ‘contacted’ was used.
Conclusions experiment 1: These findings indicate that the form of a
question (in this case, changes in a single word) can markedly and
systematically affect a witness’s answer to that question.
Experiment 2:
 Even though there was no broken glass in the film, 16 out of 50 p’s
from the smashed condition said they remember seeing broken
glass! 7 out of 50 in the hit condition stated they had seen broken
glass and 6 out of 50 in the control group (not asked a question on
speed).
 When the verb ‘smashed’ was used, participants were over twice as
likely to report seeing broken glass than when the word ‘hit’ was
used and compared to the control condition.
69
Conclusion: - Leading questions (in this case a single word) can distort a
witness’s memory for an event.
Conclusion: - This seemingly small change had consequences for how
questions are answered a week after the original event occurred.
Conclusion: - People’s accuracy for reporting the details of a complex
event is potentially distorted through the use of leading questions.
Conclusions overall:
The way a question is asked can affect the response enormously. When
we witness an event we have the information at that time of the original
event, i.e. our perception of that event, then we have extra information
supplied to us after the event, in this case the words (smashed etc). Over
time information from these two sources are integrated and mixed up
together, and we have one new memory. The participant who heard the
word “smashed” has a memory of the accident being more severe than it
was. As broken glass is often seen at a severe accident the participant is
more likely to believe that glass was present.
The questions asked can be termed 'leading' questions because they
affected the participants' memory of the event. The question contained
information about what the answer should be. Therefore, this language
can have a distorting effect on eyewitness testimony, which can lead to
inaccurate accounts. It is possible that the original memory has been
reconstructed, but it is impossible to conclude that the original memory
may have been replaced or experienced interference.
Alternative and complementary research findings:
Complementary:
Loftus (1975) showed 150 p’s a film showing a car accident, after the
showing p’s were divided into 2 groups & each group was asked 10
questions about what they had seen. Group 1 were asked questions
which matched the film they saw e.g. “How fast was the white sports car
going when it passed the ‘stop’ sign?” Group 2 was given all the same
questions except for one which was “How fast was the white sports car
going when it passed the barn when travelling on the country road?” This
question was misleading as there was no barn in the film. After a week,
70
the p’s were all asked another 10 questions the final question was “Did
you see a barn?” many more in group 2 said they had seen a barn
(17.3% as opposed to 2.7% in group 1). In group 2 the barn information
had been added to the original memory at the question stage so now it
became part of the original memory.
Loftus & Zanni study (see previous).
Bartlett (1932) found in a study that when people are given a story which
is unfamiliar to the participants, their memory is inaccurate and the
memory is changed continually over time, participants missed out
information from the story and changed the order of events. This agrees
with Loftus as it shows how fragile memory is and how it can be
reconstructed to fit in with the participant’s cultural knowledge.
Alternative findings:
Christianson & Hubinette (1993) questioned 110 witnesses who saw
between them 22 genuine bank robberies. Some of these p’s were
onlookers at the bank at the time, others were bank employees who had
been directly threatened. Victims were more accurate in their memory
and remembered what the robbers wore, their behaviour and the weapon
used than the bystanders. People are better at remembering very
stressful events if they occur in real life rather than the laboratory.
Foster et al (1994) believed that p’s in experiments are less accurate in
memory for events than in real life as if they are wrong there will be less
serious consequences. Foster showed p’s a video of a bank robbery &
asked them to identify the robber in the parade. One group were misled
to believe the robbery was a real event and their responses would
influence the trial, the other group assumed it was not a real life event.
Identification of the robber was more accurate for the first group
suggesting the consequences of identifying someone as guilty or not is
an important factor for witnesses.
Loftus (1979) showed p’s a set of slides that showed the theft of a large
red purse from a handbag, they were later read a version of what
happened which said the purse was brown; all but 2 participants correctly
remembered that the purse was in fact red. This shows that people are
not misled by information that is obviously incorrect.
Evaluation points of the study:
71
Strengths:
 The research supports the idea that memory can be easily distorted
and has implications for eyewitness testimony in court.
 You can tell cause and effect, as it is a lab experiment e.g. IV =
verb used, this affects the DV = speed estimate.
 Quantitative data gathered, useful to make clear comparisons
between groups and allow for statistical analysis.
 Practical applications - the fact that leading questions can affect
memory has important implications for interviewing witnesses by
police straight after the event and also lawyers in court some time
after. Interviewers should avoid leading questions and be careful in
how they word questions.
Weaknesses:
 There will always be individual differences where not everyone’s
memory will be inaccurate and Loftus doesn’t take this into account.
 Reductionist - reducing human memory to a simple explanation
whilst ignoring cultural factors and emotion, e.g. how that affects
memory, mood etc.
 Ethnocentric - American group of students are used as a basis to
make conclusions about human memory in all cultural groups.
 Hawthorne effect - people may change their behaviour as they
know they are in an experiment so results may not be valid, what
they state etc.
 Psychology as a science - Psychology should not just be seen as
objective and scientific this is only one of many frameworks the
researchers work in here; there are other more subjective methods
to study human behaviour like memory, such as participant
observation in a group and unstructured interviewing where more
valid responses may be given in a more informal situation.
72
73