Field experiments as used to investigate EWT

results

10/13 said there was no broken headlight and no yellow quarter panel (which was correct to identify) EWs recalled as many details 4/5 months after as they did initially Ews not influenced by leading Qs just as accurate when asked leading Qs in comparison to those who were not asked leading Qs

:) internal validity

2 groups, 1/2 asked leading 1/2 non-leading this allowed comparison between a control group and an experimental group so can establish whether IV (leadign qs) cause change in DV (Accuracy) T/f cause and effect can be established

:) ecological validity

EW behaviour displayed by Ps in a field experiment is more likely to reflect real life as ps are in their natural setting and are essentially experiencing the conditions of a real witness. They are more likely to experience stress or anxiety at what they had seen and discuss it with other witnesses, and are less likely to be forewarned to recall a situation than in a lab exp. Therefore this increases the mundane realism of such studies into EWT and allows findings to be considered more representative of a real situation

Conclusion

EWs are accurate when asked leading Qs in response to a real life crime. This criticises earlier lab research by Loftus and Palmer that suggest EWs are not. Perhaps the earlier findings were the product of demand characteristics?

:) / :( mundane realism

Real witnesses to a real crime therefore can generalise findings to everyday EW behaviour H/E once police had done their investigation, it is unusual to be interviewed again 4/5 months after incident and repeat questioning process. Therefore doesnt reflect standard EW practise so cannot be generalised

The ultimate aim of field exp is to establish...

cause and effect b/w the IV (e.g weapon focus) and EW accuracy (DV)

:) positive applications

Results show that EWs are reliable and will not be effected by leading questions and are just as accurate 4/5 months after. Therefore has practical benefits to the CJS as proves EWT are reliable

Aim:

To investigate impact of leading questions on EWT for a real crime. To investigate whether EWs would be more reliable in a field experiment rather than a lab experiment.

example of a field experiment in crim psych?

Yuille and Cutshall 1986

EWs will be randomly allocated to conditions...

a random number generator may be used to decide if they are in the exp condition (see a weapon) or control condition (dont)

An IV (such as the presence of a weapon) is manipulated by the researcher, whilst the...

accuracy/reliability of the recall (DV) is measured

It is difficult to control EVs such as EW's view of a crime (some may be close whilst others are further away), how long they are exposed to the crime (some may see from start, others may come half through) or if EW's...

are distracted (e.g some witnessed may have children who are demanding)

:( reliability

field experiments are more difficult to control than lab experiments because many situational variables may occur in a natural setting (e.g distractions from other witnesses) Therefore it is more difficult to replicate a field experiment investigating the accuracy of EWT because these extraneous variables may affect the results, leading to inconsistent results and low reliability.

procedure

interviewed 21 real witnesses of a real gun crime in vancouver by police 13 agreed to the research interview (ages 15-32) 3F and 10M witnesses interviewd 4/5 months later gave account and answered questions (same procedure as police interviews) 2 misleading qs asked about a broken headlight and a yellow quarter panel which was actually blue to half participants other half had non leading questions 'did you see a broken headlight' 'did you see a yellow quarter panel'

The eyewitnesses will see a crime in a setting which...

is likely to be familiar to them e.g a place of work or local park

:) ethics

protection from harm, havent cause any physical harm of more psych harm as they had already experience the crime. H/E revisiting the crime could be stressful

:) fewer demand characteristics

ps are likely to be unaware that they are participating in a psychological study when it is a field experiment. This makes it more likely that the responses or reactions they give within the study are genuine and indicative of real life eyewitnesses behaviour. Therefore the findings from such studies can be relied on more: this increases the validity of such studies into EWT.

:( ethics

there is greater risk that the Ps will experience psychological and or physical harm when participating as an eyewitness in a field experiment, because they will be experiencing what they believe to be a real-life incident. In addition, Ps are unlikely to have given consent, because they are usually found in public places and often do not know that they are part of an experiment. Therefore a researcher will need to weigh up the nature of the incident they are intending to stage to make sure that it does not create excessive distress, in order to uphold their ethical obligations.

less control of natural setting so although an effort is made to...

try to have a standardised procedure each EW is not likely to have an identical experince

:( reliability

was a real crime that occurred, unlikely that the exact same crime will occur again T/f not replicable to establish similar findings