Loftus & Palmer (1974)
Experiment One Method: Participants were shown a film of a multiple car crash. Then they were 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: Participants given the word 'smashed' estimated the highest speed (an average of 41 mph), and those given the word 'contacted' gave the lowest estimate (an average of 32 mph).
Experiment Two Method: Participants split into three groups. One group was given the verb 'smashed', another 'hit', and the third, control group wasn't given any indication of the vehicles' speed. A week later, the participants were asked 'Did you see any broken glass?'.
Results: Although there was no broken glass, participants were more likely to say they'd seen broken glass in the 'smashed' condition than any other.
Conclusion: Leading questions can affect the accuracy of people's memories of an event.
Has implications for police interviews.
Artificial experiment- watching a video not as emotionally arousing as witnessing an event.
The leading questions may have skewed participants' expectations, leading to demand characteristics. This would reduce the validity and reliability of the experiment.
Loftus & Zanni (1975)
Method: Showed participants a film of a car accident, then asked them either 'Did you see the broken headlight?' or 'Did you see a broken headlight?'.
Results: There was no broken headlight, but 7% of those asked about 'a' broken headlight claimed they saw one, compared to 17% in the group asked about 'the' broken headlight.
Conclusion: The use of the word 'the' is enough to affect the accuracy of people's memories of an event.
Valentine & Coxon (1997)
Aim: To study the effect of age on EWT.
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. Children were misled more by leading questions than adults or the elderly.
Conclusion: Age has an effect on the accuracy of eyewitness testimony.
Has implications in law when children or elderly people are questioned.
The experiment was artificial and so wasn't as emotionally arousing as the same situation would have been in real life- the study lacks external validity.
Aim: To study weapon focus and the effect of anxiety on EWT.
Method: In a study with an independent groups design, participants heard a discussion in a nearby room. In one condition, a man came out of the room with a pen and grease on his hands. In the second condition, the man came out carrying a knife covered in blood. Participants were asked to identify the man from 50 photographs.
Results: Participants in condition 1 were 49% accurate. Only 33% of the participants in condition 2 were correct.
Conclusion: When anxious and aroused, witnesses focus on a weapon at the expense of other details.
The study has high ecological validity.
There are ethical considerations, as participants could have been very stressed at the sight of the man with the knife.
Geiselman et al (1986)
Aim: To study the effect of the cognitive interview.
Method: In a staged situation, an intruder carrying a blue rucksack entered a classrom and stole a projector. Two days later, participants were questioned about the event. The study used an independent groups design, with participants being interviewed using either a standard or cognitive interivew. Early in the questioning, participants were asked 'Was the guy with the green backpack nervous?'. Later in the interview, participants were asked what colour the man's rucksack was.
Results: Participants in the cognitive interview were less likely to recall the rucksack as green than those in the standard interview condition.
Conclusion: The cognitive interview enhances memory recall and reduces the effect of leading questions.
High ecological validity.
Used an independent groups design- the participants in the Cognitive Interview group may have been naturally less susceptible to leading questions than the other group.