Eyewitness Testimony - Loftus

Psychology: AQA A Level, topic 2.1.14

Loftus and Zanni (1975)

Loftus and Zanni found that by even changing a single word in a question, the accuracy of recollection can be affected.

Similar to the Loftus and Palmer (1974) study, participants were shown a video of a car crash.
The participants were then either asked:
- “Did you see a broken headlight?” or
- “Did you see the broken headlight?”
The video did not show a broken headlight.

The accuracy of the recollection of events can be altered even by changing a single word.
By using the word “the”, it implied that there was a broken headlight.
By using the word “a”, the implication is there may or may not be a headlight.

The study was a laboratory study, so extraneous variables (age/gender/ethnicity/etc.) could be controlled.
So causality could be demonstrated (changing the word causes the effect of altered recollection).

But as it was a laboratory study, the setting was artificial.
By being shown film of a car crash rather than observing an actual car crash, this could alter the effect of eyewitness testimony.
This means the study lacks ecological validity.

Anxiety can affect memory accuracy. Loftus (1979) studied the effect of anxiety on eyewitness testimony of violent crime.

Anxiety can affect memory recall:
- Very low levels of anxiety (i.e. not being alert or being sleepy) can result in poor recall accuracy.
- High levels of anxiety, such as the high levels of stress and arousal after witnessing violent crime, can also result in poor recall accuracy.
So psychologists believe that there is a happy medium of optimal memory recall accuracy.

Two conditions were created in this independent design study.
In both conditions, participants heard a discussion in a room nearby.
- Group 1: participants witnessed a man come out of the room with his hands covered in grease and holding a pen.
- Group 2: participants witnessed a man come out of the room carrying a knife covered in blood.
Participants were then asked to identify the man from 50 photographs.
The participants were unaware that this was staged.

The participants in Group 1 (pen/grease) had 49% accuracy in identifying the man.
In Group 2 (knife covered in blood), the participants only had a 33% accuracy rate in identification.

Levels of anxiety affected the accuracy of recognition.
The higher levels of anxiety as a result of seeing a knife covered in blood caused Group 2 to be less accurate in identifying the man.

When witnesses were more anxious, they tended to focus on the weapon rather than the criminal.
Overall, Group 2 participants were more likely to focus on the weapon itself, rather than other details of the crime scene (such as the man).
So when witnessing violent crimes, witnesses tend to focus on central details and ignore other details.

Because the participants were unaware that the scenario was staged, the study has high ecological validity.
But there are ethical issues because of the potential trauma of witnessing a man carrying a knife covered in blood.
Psychological participants have a right to be informed and debriefed of the nature of the deception of the study.