Eye-witness testimony part 1

What is eye-witness testimony?

‘Evidence supplied by people who witness a specific event/ crime, relying on their memory’.

‘Untrustworthy evidence of guilt’ - judges/ psychologists

‘Very persuasive’ - jurors

Interesting studies: Wells (1979) … Devlin report (1976)

Factors influencing eye-witness testimony

1) Whilst registering the info

2) post-event contamination including

3) Leading questions

Background info:Two cases that changed the view in British

courts

In 1969, Laszlo Virag was convicted of stealing from parking meters and using a firearm while trying to escape police officers. Despite his alibi and other contradictions, he was identified by eight witnesses as the man who committed the crime.

While he was in prison it was found that another person had committed the crime and he was pardoned.

In 1972, Luke Dougherty was convicted of shoplifting after two witnesses picked his face out of a police album.

He was eventually cleared and both cases led to the Devlin Committee's investigation of identification evidence, which found that many witnesses overstated their ability to single out the right person.

Background info: The Devlin Report

• In 1973 there were 850 cases where EWT was the only evidence of guilt. In 74% of these cases the accused was found to be guilty.

• Prior to Devlin report it was generally assumed that eye-witness testimony was sufficiently accurate to be used as the sole evidence for prosecution – however the Devlin report recommended that no court should convict on EWT alone

• Psychologists have since tried to identify the problems with EWT and how it might be improved.

DNA

• If inaccurate EWT is used to convict someone then a miscarriage of justice can occur.

• DNA testing has shown that EWT is inaccurate• More than 200 Americans have now been freed

after being detained falsely on the evidence of EWT when DNA testing has shown it was impossible for them to have committed the crime.

• EWT is not reliable and you are going to find out why!

EWT objectives

By the end of this session you should …

1) Be able to state factors that affect the reliability/ validity of eye-witness testimonies

2) Be able to outline and describe studies demonstrating the unreliability of EWT including leading Qs

3) Be able to discuss evaluative points on research on this area

4) Be able to discuss some of the practical implications of research on EWT

Various factors affect the reliability of EWT…

• This can occur at any stage….. for example…• When registering the memory

– Expectation– Emotion/stress

• When storing the memory– Questioning & post-event contamination

• When trying to recall the memory …factors can affect the retrieval & we can use our knowledge of this to try to improve this recall eg …– The Context we recall in &– Cognitive Interview

Factors at Registration

• A) Expectations/stereotypes• A memory can be influenced by people’s

expectations• People have stereotypes & schemas which

affect memory• When we try to retrieve a memory we

reconstruct an account based partly on our memory but also partly on what we think must have happened

• The less certain our memory, the more likely we are to reconstruct

Would your life be different if you were born a different race?

Expectations that we have about groups of people can affect our memories eg Race

• In criminal cases errors are more likely to occur when the suspect’s race is different to the witness

• This is probably due to negative racial stereotypes

• Eg Howitt pg 84

Study to support:Buckhout study/Allport study

Description:Buckhout 1974

• Ps shown series of counter stereotypical pictures for a very short time. Eg a scruffily dressed white man threatening a well dressed black man with a razor.

• It was assumed at the time that many white people would hold a negative stereotype of black people eg as having criminal tendencies.

• Results: Approx 50% recalled the black man as holding the razor.

• This shows memory can be distorted by our stereotypes.

Factors at registration: b) Stress

• b) Factors to do with stress. ie usually as an EW, we will experience some stress relating to whatever we have witnessed

• Studies have found that highly stressful situations result in poorer memory recall

A study to demonstrate stress affecting recall: Peters’ study

The Peters’ study

• People going to a clinic for inoculations (jabs) met the nurse and a researcher for the same length of time.

• Later they were then asked to identify both from a set of photos.

• Results: They were better at identifying the researcher than the nurse!

• Why? The stress of having the jab was linked to the nurse so there was poorer memory/recall of her compared with seeing the researcher in a less stressful situation

Explanation of how stress affects recall

We can apply the Yerkes-Dodson law here ie

Low arousal = poor performance

Moderate arousal = performance improved

High arousal = poor performance

So applying to EWT we would assume that

highly stressful situations = low performance

or: extension study: Loftus & Burns 1982

P’s were shown a simulated armed robbery on video then tested on their recall of details

• Independent gps design with one group shown a violent version where a young boy was shot in the face whilst the other group was shown a non-violent version.

• Those who saw the violent version had less accurate & complete recall for events immediately before the shooting including the fact that one of the boys had a large “17” on his jersey.

• Ps were asked to recall 16 items & the violent version were worse on 14 of them

Why?• They believe the shock of the violence disrupts the

processing & consolidation of the memory.

Weapon focus…Loftus et al

• What colour was the 2nd man’s hair? Ie the one without the gun?

Factors at registration: Weapon focus

• Loftus believes that often highly stressful situations include weapons. She believes ps then focus on the weapon & so do not pay attention to other details eg the face of the perpetrator which would make them less reliable as witnesses.

• She calls this “weapon focus”

Study to support “Weapon focus” Loftus et al

• Ps shown a video of a restaurant where either:• i) a man points a gun at the cashier & she hands

over money • Ii) or he hands her a cheque and she gives him

money. • The eye movements of all ps were monitored &

their recall was tested.• Results: Ps in the weapon situation fixated more

on the gun than the other gp. • Their recall was poorer and they were less able

to identify the man from a set of photos.

Evaluative points: the relationship between emotion/stress & EWT is not simple

Real life research eg Yuille & CutshallAim: to investigate EWT in a real life eventMethod: This was a case study of a thief in Canada who stole guns/money but was shot (6 times) whilst trying to escape & was killed.

21 witnesses gave evidence to the police & then 13 agreed to be interviewed by Psychologists btw 4/5 months after the event. During these interviews they were asked 2 misleading Qs.

Results: Unlike the lab studies, the misleading Qs did not affect their recall. There were very few/no reconstructed facts.

Conclusion: in a real life highly emotional event, EWT was v accurate

Extra: also no relationship at all was found between the levels of stress reported at the time and the accuracy of recall…in fact the most distressed witnesses had the most accurate recall.

Evaluation of Yuille & Cutshall

• This study had good ecological validity because these were the actual people who had witnessed the actual robbery therefore it was more convincing research

• However, those who experienced more stress were the ones that were closer to what was going on so the close proximity probably meant they gathered more detail which could have counteracted the negative effects of the higher stress.

Pg 86

• Extra reading

Factors affecting EWT after the event: Questioning & post-event contamination

• A huge amount of research has gone into demonstrating how EWT can be influenced by post-event questioning & how misleading info can be inserted into a stored memory using Leading Qs

What are leading questions? ‘

• Questions that suggest an answer by the way in which the question is worded’

Leading QuestionsLeading Questions

1. What was the advert we watched advertising?2. What was the skin colour of the man who appeared at the very

beginning of the advertisement? 3. What colour t-shirt was he wearing? 4. Describe the appearance of the male break dancer who appeared in

the very first clip? 5. What colour were the dungarees and sandals worn by the Asian girl

who appeared in the advert? 6. What type of phone did the male performer have hanging around

his neck? 7. How many people in the advert wore sunglasses? 8. Six different people appeared in the advert – how many were male

and how many were female?9. Describe the appearance of the female wearing the pink hoody in

the middle scene?

10. In the final scene how many of the performers wore multi-coloured puffer style jackets?

Pick 3 examples of leading questions and explain whyPick 3 examples of leading questions and explain why

Extension task: Pick two questions and rephrase them so that they are no longer leading questions.

Study to investigate post-event contamination through the use of questions

a) Loftus and Palmer, 1974

Aim:

Method part 1: 150 ps asked to view a 1 min film of a car crash & then

a) describe what happened

b) Answer Qs on the film

Loftus and Palmer

6 conditions which were asked the Q “ how fast were the cars going when they …

• Hit

• smashed

• collided

• bumped

• contacted the other car

• The control group was not asked the Q about speed

Results

The estimated speed was affected by the verb

‘smashed’ = 41mph / ‘hit’ = 34mph

Results. Guess which word goes with which speed

estimateBar chart showings findings from Experiment 1

32 3437 39 41

0

10

20

30

40

50

Critical word in leading question

Sp

eed

(m

ph

)

Bar chart showings findings from Experiment 1

32 3437 39 41

0

10

20

30

40

50

Contacted Hit Bumped Collided Smashed

Critical word in leading question

Sp

eed

(m

ph

)Bumped

Hit

Contacted

Smashed

Collided

Stage 2 of the expt:

• Method part 2: a week later they were asked further Qs like “Did you see any broken glass?” when there was actually no broken glass.

• Results part 2: of those in the “smashed” gp, 32% “saw” broken glass compared with 14% of the “hit” gp and 12% control gp.

• Conclusion: the way the Q is asked influences the answers both immediately eg on the estimation of speed but also later on recall. Here post event contamination was clearly evident

b) Leading Qs study:Loftus & Zanni

• Showed how just changing one word in a question can contaminate a memory

• They showed a film of a car crash to ps & asked either “Did you see the broken headlight” or “did you see a broken headlight”

• Results: The use of the word “the” resulted in 17% reporting having “seen” the broken headlight cf. only 7% in the “a” group. In other words the wording affected post-event recall.

1. Leading questions affect the participants’ memory of events

2. Information provided after the event has occurred can change the actual memories that you have stored

3. Language can have a distorting effect on eye-witness testimonies

Important implications …

Conclusion

However….Evaluation of post event contamination

Loftus’ red purse study

• Ps are less likely to be mislead on inaccurate details when they are asked something central to the event.

• Loftus found that 98% of people who had watched coloured slides of a man stealing a red purse from a woman’s handbag, remembered the purse was red even though it was implied to them that it was brown.

Explaining why: Individual differences on being mislead

• Ceci found children to be more easily misled

• Loftus et al found older people more likely to be misled, particularly older males.

How can we be misled so easily?

• McCloskey et al calls this the Misinformation effect & divides this into 2 reasons:

• A) Misinformation acceptance ie that you didn’t register the info in the 1st place so when someone feeds you incorrect info, you accept this misleading info as correct i.e. like informational conformity

• B) Demand c’s ie that as the info was provided by the researcher, they accept it because they want to agree with them

Evaluating EW studies

• 1 criticism of these is that they are lab studies and so p’s would not be expecting anyone to try to implant incorrect information so this sort of research lacks ecological validity

• However even when p’s are warned about misleading post event info, memory is still affected (Eakin et al.)

Eval 2

• Some argue that what is occurring is “response bias hypothesis” ie that they are merely going along with the interviewer rather than contradicting them even though their actual memory might still be intact (ie in its original form)

• Loftus also believes that the tendency to accept misinformation increases as memory fades over time

Eval 3

• Cohen believes that problems in EW studies are due to methods used eg often closed Qs are used such as “was the lady carrying a bag? Yes/no” whereas in reality in interviews they would be asked things like “ Tell me what the lady was carrying”

Which professions need to consider the implications of this research?

Police; judges; lawyers; politicians; teachers etc…

How can we tackle the problems of leading questions?

Home Office guidelines …

•Avoid repeated interruptions during interview

• Encourage free recall and general open ended questions

• Professionals pay careful attention to the phrasing of questions

Implications of research – what do you think?

1. What is a leading question?

2. Is L&P research a laboratory experiment or a field experiment?

3. What is the dependent variable in the experiment?

4. Write down three conditions in L and P study.

5. Which condition generate ‘highest speed’ responses?

6. In one sentence describe the results of the experiment?

7. Note down one criticism of the study.

8. In one sentence describe the main conclusion of the study.

9. Name a profession that should consider the implications of this research.

Task – Revision QS on the Loftus and Palmer study

Improving memory recall: a) Cues that trigger memories

• Remember cue dependent forgetting?

• Ie that we use either contextual cues or state cues when trying to remember

• This applies with EWT showing that people’s memory is better if they recall in the same context as they learnt the info.

Study to support: Malpass & Devine

• Showed p’s a film of some vandalism & interviewed them 5 months later

• Group A were reminded of the day, the room & immediate reactions & their recall was much better than the control gp who were not given any contextual cues.

• However sometimes contextual cues can backfire! See pg 86 textbook

b) The Cognitive interview

• See other notes on this...