Loftus and Palmer

Aim: To investigate the effects of leading questions on the recall of an event 

Research method: Labatory experiment

IV: the verb used in the critical question

DV: the estimated speed of the cars

Design: Independent measures

Sample: 45 students from USA

Procedure:

• Participants placed in groups and shown 7 films of traffic accidents, each were 5-30 seconds long.
• After each film, they were given a questionnaire
• In this they would write an account of what happened and then they were asked a series of questions, involving the critical question.
• Critical question: how fast were the cars going when they (VERB) each other?
• 9 participants were given the verb 'smashed', 9 given 'collided', 9 given 'bumped', 9 given 'hit', 9 given 'contacted'.

Findings:

The mean estimate for each verb;

• Contacted: 31.8
• Hit: 34
• Bumped: 38.1
• Collided: 39.3
• Smashed: 40.8

Conclusions:

• People are not very good at estimating speed cars are actually travelling- students estimates were far off the actual speed
• Questions can affect recall whether this is due to:
• Response bias- the verb influenced the response, for example the stronger verb biases their response to a higher estimate, or
• Memory is altered- the verb itself causes actual change in the participants memory

Aim: To see why participants in the first experiment estimated different speeds depending on the verb given; whether it is due to response bias or memory being altered.

Research method: Labatory experiment

IV: the verb used in the critical question

DV:

1. The estimated speed of the cars

2. Whether the participants reported seeing broken glass

Design: Independent measures

Sample: 150 students 

Procedure:

• Participants shown film of car crash
• Given a questionnaire, asked to describe accident in detail then answered questions about accident including critical question
• Critical question: How fast were the cars going when they (VERB) into each other?
• 50 participants given the verb 'smashed' 
• 50 participants given the verb 'hit'
• 50 participants were not asked about the speed (control group)
• One week later, the participants were given the second questionnaire with questions on the accident including the critical question
• Critical question: Did you see any broken glass? Yes/No
• There was no broken glass in the film.

Mean estimate of speed

• Smashed: 10.46
• Hit: 8
• Mean estimate significantly different p<0.05. So the faster verb affected the participants estimates

Responses to broken glass

                                  Yes                                            No

Smashed group:        16                                             34

Hit group:                    7                                              43

Control group:             6                                              44

• Smashed: 68% not effective
• Significant at p < 0.025

Conclusions:

• Information given after an event can alter the recall of memory.

Evaluation

Controls: Both studies were experiments conducted under labatory conditions, with a number of controls in place such as length of film shown. This allows for cause and effect relationships to be inferred.

Replication: As all studies took place within a labatory environment and had detailed procedures, it allows research to be replicated so we know it was not due to chance.

Ethics: The study is ethical in the fact that the participants were not experiencing a live car crash, this avoids a lot of psychological harm. However, those who may have been in a car accident may have felt some psychological stress. Also, they did not gain valid consent from their participants, they used deception as if the participants were aware of the aims it would have affected their behaviour (demand characteristics). The research is justified in the fact it is important to understand the effect of leading questions in EWT as it could lead to loss of liberty.

Validity: The research took place under labatory conditions, therefore it lacks ecological validity. In real life when people experience a car crash they are more likely to have a more emotional rection. They may not be as focused as the students watching the video. These factors could have affected the memory of the event. Yuille and Cutshall studied witnesses of a real-life violent crime and found that their memories of the event were very accurate and did not change when given leading questions.

Generalisability: The participants were all students, therefore they were unlikely to have any or a lot of experience of driving. This could have affected their confidence of giving speed estimates, this may not be the same for experiences drivers who may have felt more confident and more accurate answers.