eyewitness testimony

- evidence provided by people who witnessed a particular event or crime. it relies on recall from memory

- it includes descriptions of criminals and crime scenes

- witnesses are often inaccurate in their recollection of events and the people involved 

- many cognitive psychologists focus on working out what factors affect the accuracy of eyewitness testimony, and how accuracy can be improved in interviews

Method: p's were shown a film of a multiple car crash. they were then asked a series of questions including 'how fast do you think the cars were going when they HIT? in different conditions the word HIT was replaced with SMASHED, COLLIDED, BUMPED or CONTACTED.

Results: it was seen that p's given the word SMASHED estimated the highest speed and those given CONTACTED gave the lowest estimate

Method: p's were split into 3 groups. one was given the verb smashed, another hit and they third control group wasn't given any indication of the vehicles' speed a week later they were asked 'did you see any broken glass?' 

Results: although there was no broken glass p's were more likely to say they had seen broken glass in the 'smashed' condition than any other 

Evaluation: this was an artificial experiment, it is not emotionally arousing. A later study found that p's who thought they'd witnessed a real robbery gave a more accurate description of the robber. may lead to demand characteristics, if they may have guessed the nature of the experiment then this could reduce the validity and reliability of the experiment.

Method: 3 groups of participants (children, young adults and elderly people) watched a video of a kidnapping. they were then asked a series of leading and non-leading questions about what they had seen.

Results: Both the elderly people and the children gave more incorrect answers to non-leading questions. but children were more misled by the leading questions than the others

Evaluation: experiment was artificial so it was no emotionally arousing, study lacks external validity.

Method: independent groups design, participants had heard a discussion in a nearby room. in one condition the man came out of the room with a pen and grease on his hands. in the second condition he came out of the room with a knife covered in blood. p's were asked to identify the man from 50 photos.

Results: in condition 1 49% were accurate. in condition 2 only 33% of participants were correct.

conclusion: when anxious and aroused, witnesses focused on the weapon at the expense of the other detail.

Evaluation: high ecological validity, as the p's weren't aware that it was staged, however this means that there are also ethical considerations, as p's could be very stressed at the sight of the man with the knife.

Developed by Geiselman to try and increase the accuracy of witnesses' recall of events during police questioning:

• interviewer tries to make the witness relaxed and tailors the language to suit the witness
• witness recreates the context of the crime scene 
• witness reports absolutely anything they can remember
• witness is asked to recall details of the crime in different orders
• witness is asked to recall from different perspectives 
• interviewer avoids any judgemental and personal comments

Method: an intruder carrying a blue rucksack entered a classroom and stole a slide projector, 2 days later p's were questioned about the event. independent groups design, p's were either questioned using the standard interview procedure or the cognitive interview. early in questioning p's were asked was the guy with the green backpack nervous, later in the interview they were asked to identify the colour of the mans backpack.

Results: those in the cognitive interview were less likely to recall the backpack as being green than those in the standard interview 

Conclusion: cognitive interview technique enhances memory recall and reduces the effect of leading questions 

Evaluation: experiment was conducted as though it was a real crime so high ecological validity. experiment used an independent groups design so the disadvantage is that the p's in the cognitive interview may have been less susceptible to leading questions than those in the other group.