Cognitive - Eye Witness Testimony - Misleading Information

Eyewitness testimony refers to the use of eyewitnesses to give evidence in court concerning the identity of someone who has committed a crime.

Loftus and Palmer (1974) 

Experiment 1

Procedure

- 45 students shown 7 films of traffic accidents.
- Students were given questionnaires after films asking them to describe the accident and answer questions.
- One critical question where the verb was changed between groups. Verbs uses were: hit, contacted, bumped, collided, smashed. 
- The question asked them to estimate the speed the cars were travelling at.

Findings

- The group given the word 'smashed' had the highest speed estimate.
- 'Contacted' had the lowest speed estimate.

Experiment 2

Procedure

- New participants divided into 3 groups and shown a film of a car accident.
- Group 1 given smashed. Group 2 given hit. Group 3 had no speed question.
- Participants were asked to return 1 week later and answer questions about accident.
- Were asked if they saw any broken glass despite there being none in the video.

Findings

- 'Smashed' group more likely to think there was broken glass.

Evaluation

+ Extraneous variables are controlled because it is a lab experiment.
+ Independent groups - no order effects.
+ Easily replicated - high reliability.
+ Cause and effect can be established.
+ Research has led to implications and eyewitness testimonies now can't stand alone in court.

- Lacks mundane realism - low ecological validity.
- Independent groups - participant variables.
- Investigator bias.
- Demand characteristics.
- Questionnaires cause social desirability bias.
- Could be deceptive.
- Small sample size - only students - low population validity.

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Loftus (1975)

Procedure

- Showed 150 participants a film of a car accident and divided into 2 groups. 

- Each group asked 10 questions. 

• Group 1: Asked questions consistent with the film. 

• Group 2: Asked same questions except for one: "How fast was the car going when it passed the barn?" - there was no barn in the video. 

- After 1 week, participants were asked another 10 questions and both groups asked if they saw a barn. 

Findings 

• 2.7% of Group 1 gave incorrect answer. 

• 17.3% of Group 2 gave incorrect answer.