Factors affecting Eyewitness Testimony

Eyewitness testimonies are used in many court cases and are seen to either make or break the case for the defendant.

This means that they must be accurate at all costs and to get an eyewitness testimony complete, accurate and truthful there are many things that must not happen to affect the persons memory.

The effect of misleading information on the accuracy of eyewitness testimony:

There are some main factors that affect the accuracy of a memory for an event which seem to occur after the event has taken place.

Memories are fragile and subject to distortion by post event information.

Loftus and Palmer (1974) arranged for participants to watch film clips of car accidents and then gave them a questionnaire about the accient.

In the critical question (a leading question) participants we asked to describe how fast the cars were travelling:

'About how fast were the cars going when they ________ each other?'

There were five groups of participants; each was fiven a different verb in the critical question:

1) Hit
2) Contacted
3) Collided
4) Bumped
5) Smashed

The mean estimated speed given in response to the critical question was calculated for each group.

The verb 'contacted' resulted in a mean speed estimate of 31.8 mph.

For the verb 'smashed', the mean speed estimate was of 40.5 mph.

The verb in the eading question biased the eyewitness' recall of the event.

The response bias explanation suggests that the wording of the question has no real effect on the participants memory but, instead influences how they choose to respond to the question.

The word 'smashed' encouraged them to respond with a higher and faster speed.

When co-witnesses to a crime disucss it with each other (post-event discussion), their eyewitness testimonies may become contaminated.

This is because they combine (mis)information from other witnesses with their own memories.

Gabbert et al. (2003) studied participants in pairs.

Each participant watched the video of the same crime, but filmed from different points of view.

This meant that each participant could see elements in the event that the other could not.

For example, only one of the participants could see the title of a book being carried by a young woman.

Both participants then discussed what they had seen before individually completing a test of recall.

The researchers found that 71% of the participants mistakenly recalled aspects of the event that they did not see in the video but they had picked up on in the discussion.

The correspondance figure in the control group, where there was no discussion was 0%.

Gabbert et al. concluded that witnesses often go along with each other, either to win social approval or because they believe the other witnesses are right and they are wrong.

This is known as memory conformity.

STRENGTH

Research into misleading information has real-life application.

The research has led to important practical uses for police officers and investigators, important because the consequencesof inaccurate EWT can be very serious.

Loftus (1975) claimed that leading questions can have such a distorting influence on memory that police officers need to be careful about how they phrase questions when interviewing eyewitnesses.

Research into EWT is one area where psychologists can make an important difference to the lives of real people, e.g. by improving how the legal system works and acting as an expert witness.

LIMITATION

Loftus and Palmer used artifical materials when conducting their study.

Participants watched film clips of accidents, a very different experience from witnessing a real accident (e.g. it was less stressful).

Yuille and Cutshall (1986) found that witnesses of a traumatic real armed robbery had very accurate recall after 4 months.

This shows that using artifical tasks tells us little about how leading questions affect EWT in real crimes or accidents.

LIMITATION

Lab studies of EWT suffer from demand characteristics.

Research participants usually want to be helpful and attentive, so when they are asked a question and they do not know the answer, they guess, especially for yes or no questions.

Participants might be asked 'did you see a blue car?' and even if there was no blue car in the film, the participants may reply yes because it seems more helpful than if they were to say no.

This challenges the validity of EWT research.

Studies tend to measure the accuracy of eyewitness memory but the answers eyewtitnesses give may not actually reflect their memory.

LIMITATION

Many EWT research studies lack external validity.

Foster et al. (1994) argue that what you remember as an eyewitness can have important consequences in the real world, but the same may not be true in research studies.

Real eyewitnesses search their memory with more effort becasue their testimony may lead to a successful conviction (or wrongful if inaccurate).

This is not true in research studies.

Therefore, EWT accuracy may be greater in the real world because of the seriousness with which the eyewitnesses undertake their role.

All stressful situations cause anxiety and crimes and accidents are no exception. When we witness these events, we experience both psychological and physiological changes that could affect what we later remember.

Anxiety has strong emotional and physical effects but it is not clear whether these effects make recall better or worse.
To solve this there is much evidence to support both arguments.

Anxiety creates physiological arousal in the body, which prevents us paying attention to important cues which results in recall being worse.

One approach used to study the effect of anxiety on the accuracy of recall in EWT is the use of weapons (which create anxiety).

This approach is known as the weapons focus effect.

Johnson and Scott (1976) led participants to believe that they were going to take part in a lab study.

While seated in the waiting room participants heard an argument in the next room.

In the 'low anxiety' condition, a man then walked through the waiting room carrying a pen with grease on his hands.

In the 'high anxiety' condition, other participants overheard the same argument, but this time accompanied but the sounds of breaking glass before a man walked through the waiting area holding a paper knife that was covered in blood.

The participants later picked out the man from a set of 50 photos:

49% of the participants who had deen the man carrying the pen were able to correctly identify him.

Only 33% of those who had seen him carrying the knife were able to correctly identify him.

The tunnel theory of memory argues that eyewitnesses attention narrows to focus on a weapon, because it is the source of the anxiety.

This is known as the Weapons Focus Effect.

When we witness a crime, our fight or flight response is triggered which increases our alertness.

This response also improves our memory for the event becasue we become more aware of the cues in the situation.

Yuille and Cutshall (1986) conducted a study of a real-life shooting in a gun shop.

The shop owner shot a theif dead.

There were 21 witnesses- 13 agreed to take part in the study.

The interviews were held 4-5 months after the incident and these were compared with the original police interviews made at the time of the shooting.

Accuracy was determined by the number of details reported in each account.

The witnesses were also asked to rate how stressed they had felt at the time of the incident and asked if they had any emotional problems since the event, such as sleeplessness.

The witnesses were very accurate in their accounts and there was little change in the amount or accuracy after 5 months- though some details were less accurate, such as the recollection of the colour of items and age/height/weight estimates.

Those participants who reported the highest levels of stress were most accurate with and 88% rate of accurate recall compared to 75% in the less stressed group.

According to Yerkes and Dodson (1908) the relationship between emotional arousal and performance looks like an 'inverted U'

Deffenbacher (1983) applied this to EWT.

Lower levels of anxiety produce lower levels of recall accuracy, but memory becomes more accurate as the level of anxiety increases.

However, there comes a point where the optimal level of axiety is reached. This is the point of maximum accuracy.

If an eyewitness experiences any more stress than this, then their recall of the event suffers a drastic decline.

LIMITATION

Johnson and Scott's study is that is may be studying the effects of surprise rather than the effects of anxiety.

Participants may focus on a weapon because they are surprised at what they see rather than becasue they are scared.

Pickel (1998) used scissors, handgun, wallet and raw chicken as hand held items in a hairdressing salon.

EWT accuracy was poorer for high unusualness (chicken and handgun).

Therefore, the weapon focus effect is due to unusualness rather than anxiety/threat and therefore tells us nothing specifically about the effects of anxiety on EWT.

LIMITATION

Field studies may lack control of variables as the real-life witnesses were interviewed sometime after the event.

Many things can happen to them in the meantime that researchers cannot control.

For example, eyewitnesses discuss the event with others or read accounts of the incident in the media.

These extraneous variables may be responsible for (in)accuracy of recall, not anxiety and it is difficult to isolate these variables.

LIMITATION

Field studies may lack control of variables as the real-life witnesses were interviewed sometime after the event.

Many things can happen to them in the meantime that researchers cannot control.

For example, eyewitnesses discuss the event with others or read accounts of the incident in the media.

These extraneous variables may be responsible for (in)accuracy of recall, not anxiety and it is difficult to isolate these variables.

LIMITATION

There are many ethical issues associated with this research area as creating anxiety in participants is potentially unethical because it may subject people to psychological harm purely for research purposes

So, real-life studies are beneficial: psychologists interview people who have already witnessed an event, so there is no need to create it.

Ethical issues don't challenge the findings of studies but they do raise questions about conducting such research.

LIMITATION

Demand characteristics may affect lab studies on anxiety as most participants that take part in lab studies are aware of the fact that they are watching a filmed crime for a reason to do with a study.

They may work out that they will be asked questions about what they have seen and they may then give the responses which they believe to be helpful to the researcher.

So the research is not measuring the accuracy of EWT and this reduces the validity of the research investigating the effects of anxiety.

Eyewitness testimony- the ability of people to remember the details of the event, such as accidents and crimes, which they have observed. Accuracy can be affected by factors such as misleading information and anxiety.

Misleading information- incorrect information given to the eyewitness usually after the event. It can take many forms, such as leading questions and post-event discussion between co-witnesses or other people.

Leading question- a question that, because of the way it is phrased, suggests a certain answer.

Post-event discussion- occurs when there is more tha  one witness of an event. Witnesses may discuss what they have seen with a co-witness or with other people. This may influence the accuracy of each witness's recall of the event.

Anxiety- a state of emotional and physical arousal. The emotions include having worried thoughts and feelings of tension. Physical changes include increased heartrate and sweatiness. Anxiety is a normal reaction to stressful situations but can affect the accuracy and detail of eyewitness testimony.