Loftus et al.1987 - Anxiety affects the accuracy
SUPPORTS YERKES-DOBSON LAW&WEAPON-FOCUS EFFECT
METHOD: Field experiment using independent measures design.
PROCEDURE: Participants were left in a waiting room outside a lab whilst waiting for the 'real' study to start. While waiting two situations occured: 1) They overheard a low key discussion in a lab about an equipment failure. A person emerged from the lab holding a pen in grease covered hands. 2) They overheard a heated and hostile debate between two people in a lab with sounds of breaking glass and crashing chairs. A man emerged from the lab holding a paper knife covered in blood.
FINDINGS: 49% correctly recalled the confederare from 50 photos in the condition where the man emerged holding the pen in greasy hands, whereas 33% correctly recalled the confederate from 50 photos when the person emerged holding as paper knife covered in blood.
CONCLUSION: The results show that high levels of anxiety have a negative effect on the accuracy of EWT. This is explained through the WFE. This is when witnesses of a crime that involves a weapon focus on the weapon and are therefore less likely to recall details about the suspect or surrondings accurately.
Loftus&Palmer.1974 - Misleading info affects EWT
METHOD:Two lab studies using independent measure design. IV in both experiments was the verb used. DV in experiment 1 was the participants speed estimate. DV in experiment 2 was whether the participants believed they saw glass
PROCEDURE: Experiment 1: PPs were each shown seven film clips of traffic accidents made for driver education. They were then asked to write an account of what they had just seen and asked specific questions. There were five conditions in the experiment and ther IV was maniuplated by means of the wording of the questions, The critical question was 'About how fast were the cars going when they ***** each other'. The following words were inserted into the question: C1:SMASHED, C2: COLLIDED, C3: BUMPED, C4: HIT and C5: CONTACTED. Experiment 2: PP's viewed a short film which consisted of a 4 second scence of a multiple car accident and were then questioned about it. There were 3 conditions and the same critical question was used as in experiment 1. The verbs used were: C1: SMASHED, C2: HIT and C3: CONTROL (not crticial question asked). One week later the PPs returned and without viewing the film again, they answered a series of questions about the accident. Ther critical question was 'Did you see any broken glass'. There infact was no broken glass in the film.
FINDINGS: Experiment 1: C1: SMASHED mean estimate speed(mph) was 40.8 C5: CONTACTED was 31.8. The results show that the phrasing of the questions brought about change in speed estimate. With smashed eliciting a higher estimate speed than contacted. Experiment 2: Results show that the verb smashed in the question did have a significant effect on the inaccurate recall of glass in the film. Those participants that heard the word 'SMASHED' were more than twice as likely to recall seeing broken glass.
CONCLUSION: Experiment 1: 1) The results could be due to the distortion in the memory. The memory of how fast the cars were travelling could have been distorted by the verbal label used in the question. 2) The results could be the result of demand characteristics. PPs may not have been sure of the speed, so adjusted their estimate to fit in with the expectations of the questioner. Therefore, their memory was not affected. Experiment 2: They concluded that the results show that two kinds of information go into a person's memory of an event - information obtained from percieving an event and information supplied after the event. Overtime, the information from these two sources may be intergrated into one memory so we are unable to tell from whih source specific detail is recalled, and if information supplied after the event is incorrect, it could make our memory of the event inaccurate.
Yuille&Cutshall.1986 - Anxiety&Misleading info EWT
METHOD: Case study using independent measures design ANXIETY&MISLEADING INFO
PROCEDURE: A thief entered a gun shop and tied the owner, and stole money and guns from the shop. One the owner freed himself he went outside to take the registration number of theif. However, the thief had not yet gone and shot the owner twice from six feet away. The owner then fired six bullet from the revolver at the thief who was killed. The owener, after surgery managed to recover. The researchers interviewed the PPs 4/5 months after the incident. The interviews were recorded and transcribed. They gave their accounts first and then were asked specific questions. Two leading questions were asked. Half the group were asked if they saw A broken headlight, and the other half if they saw THE broken headlight, when in fact there was no brokn headlight in the theif's car. Similarly, half the group were asked about A yellow panel on the car, and the others about THE yellow panel, whereas the panel was really blue. Finally, witnesses were asked to rate the stress they had felt at the time of the incident on a 7 point scale and if they had experienced any emotional problems at the time or since the event, such as sleeplessness.
FINDINGS: They found that the misleading questions had very little effect in their recall. Ten of the eye-witnesses said that there was no broken headlight and no yellow panel at all on the thiefs car - which was correct to identify. They found that the witnesses who recorded high levels of stress at the time of the incident gave the most accurate accounts.
CONCLUSION: They concluded that eyewitnesses were actually very reliable, and that high levels of stress and misleading questions associated with witnessing a criminal event does not affect the accuracy of the testimony.
Loftus et al.1987 Strengths and Weaknesses
- This is a field study that placed PPs in a REALISTIC situation where they believed that a real crime was taking place. Therefore, the study has GOOD ECOLOGICAL VALIDITY because the findings can be GENERALISED to real life settings due to the realistic nature of the study.
- There is a large amount of SUPPORTING EVIDENCE for the WEAPON FOCUS EFFECT. e.g. Steblay .1992 carried out a meta-analysis of studies concerned with the weapon focus effect and found that the presence of a weapon did REDUCE the chancesof a witness CORECTLY IDENTIFYING the person holding it. However, it is not clear whether the studies included in the meta-analysis were lab, field or natural studies, which is a PROBLEM because it seems that the effect of anxiety on EWT DIFFERS depending on the SETTING in which the study is carried out.
- The findings of this study are challenged by research of real witnesses to real violent crime, such as Yuille and Cutshall(findings of their study) This suggests that there may have been DEMAND CHARACTERISTICS in Loftus et al's study, As the PPs were already in a lab based setting, waiting to take part in a study, they my have guessed that the set up incident was not real and therefore not felt such high levels of anxiety as Loftus et al. assumed.
Loftus&Palmer.1974 Strengths and Weaknesses
- The research has WIDER IMPLICATIONS. Based on evidence like that of Loftus's, THE DEVLIN REPORT (1976) recommended that the trial judge be required to instruct the jury that it is not safe to convict on a single eye-witness testimony alone, except in exceptional circumstances or when there is substatntial corroborative evidence. It has also led to the police and lawyers being urged to use as few leading questions as possible, although in reality this practice is still widely carried out.
- It is not TYPICAL to REAL LIFE SITUATIONS. The experiements carried out by Loftus are artifical in the sense that they are different to how people would normally witness events. For example, when the PPs were giving their estimate speeds, they did not have any personal involvement in the judgement and had not taken part in the event. When we witness something in everyday life, we usually have some involvement in the people or the action. Therefore it should be difficult to GENERALISE the findings for lab experiments because they are noT ECOLOGICALLY VALID.
- The use of PPs. Students are not REPRESENTATIVE of the GENERAL POPULATION. They may be less experienced drivers and therefore less confident in their ability to estimate speeds. This may have influenced them to be more swayed by the verb in the question.
Yuille&Cutshall.1986 Strengths and Weaknesses
- This is a NATURAL study that looks at a real incident with real eye-witnesses. It therefore has STRONG EXTERNAL VALIDITY, which lab experiements, such as Loftus and Palmer which has previously been used to look at EWT. The fact that the findings of this study are different the the findings of lab studies such as Loftus and Palmer further suggests that lab based research lacks validity because the results produced cannot be GENERALISED to real life EWT.
- Difficult to GENERALISE the findings of the study, as this was a study of EWT in a unique situation and it would be difficult to find a similar one naturally occuring again. Furthermore, as there were only 13 PPs to this study- 8 of the original witnesses either moved or did not want to take part, the study lacks POPULATION VALIDITY because the sample size was so small and only represented a very small group of Candians. Therefore, the findings cannot be GENERALISED to the WIDER POPULATION, as this group of people may happen to have better or worse memory functioning than the wider population.
- There was also probklems with the SCORING PROCEDURE which was set up, which would affect the INTERNAL VALIDITY of the study. For example, with the question the researchers used the same age of the suspect. The theif was actually 35yrs old, and when asked to estimate his age, most eye witnesses said he looked as if he was in his early 20's - which was marked as inaccurate memory, even though in reality he did actually look as if he was in his 20's.
Anastasi&Rhodes.2006 - Age affects EWT
METHOD: Lab experiment using independent measures design
PROCEDURE: PP's were split into three age groups (young18-25, middle aged35-45 and old55-78). Each participant was shown 24 photographs of a mixture of age groups, and asked to rate their attractiveness. After a short filler activity, they were shown 48 photographs - 24 the same as before and 24 different that acted as 'distractors'. The pps had to say which ones they'd been shown earlier. They measured the correct recognition rates for each group.
FINDINGS: They found that the older age groups were less accurate in their recall and the middle aged and young age groups were more accurate. However, all three groups were better at remembering and recognising photographs of their own age group (own-age bias).
CONCLUSION: They concluded that old age does have negative effects on the accuracy of EWT,as the older PPs were less accurate in their ability to recognise faces. However, they also conluded that own age bias does seem to affect the accuracy of facial recognition, as each age group was more accurate in recognising faces from their own age group.
Anastasi&Rhodes.2006 Strengths and Weaknesses
- This reserach has important IMPLICATIONS for EWT research, as it suggests that the stimuli used in such research can indeed have an influence on results recorded. Therefore EWT research should be constrcuted carefully, taking into consideration such extraneous variables, and researchers should use stimuli photos that show people of a simnilar age as their PPs in order to control own age bias.
- Supported by a LONGITUDINAL STUDY of own age bias by Hill(2012), who found that as children developed from the age of 6-10, they did not necessarily get better at recognising faces, but at each age, were better at recognising faces from their own age group. For example, at age 8, they had high accuracy rates for recognising 8 year old faces than 7 or 9 year olds.
A possible explanation for this is offered by the Differential Experience Hypothesis (Brigham&Malpass 1985). According to this hypothesis, we are better at recognising faces from our own age group because we have more experience of that age group, and are therefore more practiced in processing facial features of that age. This is supported by research that has found that teachers are less prone to own age bias than other adults due to having lots of experience in recognising faces of different age groups (Harrison&Hole 2009)