Loftus et al., (1987) – Some Facts About “Weapon Focus”, Journal of Law and Human Behaviour 11 (1), 55–62

 

Background

This is the second study we look at from the ‘Interviewing Witnesses’ section of ‘Making a case’. As part of your OCR A2 Psychology Exam. It is further categorised into ‘Weapons Focus and Factors Affecting Reconstruction.’

“‘Weapon Focus’ refers to the concentration of a crime witness’s attention on a weapon, and the resultant reduction in ability to remember other details of the crime.”

When a weapon such as a gun is present during a crime. Witness recall of the offender is significantly reduced. The reason behind this is witnesses tend to focus on the weapon, not the offender. This is due to attentional narrowing, which Loftus believed is present due to evolution.

Good news! There is not a background study for this study!

Aim

To provide support for the ‘weapon focus’ effect. Which affects witnesses during crimes where a weapon is present.

Design

Laboratory Experiment

Participants

Experiment One

Loftus et al., used 36 students from the University of Washington where Loftus is a professor. All the students were aged between 18-31. 13 Participants were Psychology students participating in exchange for extra credit in their Psychology Class. The remaining 23 were recruited through an advert and were paid $3.50 for their participation in the experiment.

Experiment Two  

80 Students from the University of Washington.

Procedure

Experiment One

Loftus et al., used two sets of 35mm slides. Each set contained 18 slides. Both series showed a group of people moving through a queue in a Taco Time restaurant.

There were two conditions, the control and the experimental. Person B acted differently in both conditions. Person B was the second person in line.

In the experimental condition, person B pulled out a gun.

In the control condition, person B handed the cashier a cheque.

Apart from the differences in person B, all the other slides were exactly the same in both conditions.

Each slide was shown for 1.5 seconds.

The participants were told that the study was aiming to study proactive interference.

After watching the slides the participants were given a 20 item multiple choice questionnaire. The participants were also given a line up of twelve photos of people’  s heads, they were then asked to rate on a scale of 1-6 (1- guess, 6- very sure) how confident they were of their identification of person B.

Eye movements were measured with a corneal reflection device.

Loftus et al., then replicated the experiment with 80 students and achieved the same results.

Results

Participants answers on the questionnaires were not significantly different between both conditions. Loftus et al,. calculated 8.5% of the result were due to chance. In the control condition without the gun, 38.9% (7 people) identified the correct person B, whereas only 11.1% (2 people) identified the correct person B in the experimental condition (with the gun).

There was no difference between the self-reported levels of confidence reported by the two groups.

Eye measurements showed on average the people in the experimental condition spent 3.72 seconds looking at the gun, where as the people in the control condition spent an average of 2.44 seconds looking at the cheque.

Conclusions

As expected, the participants spent longer looking at the weapon when one was present, as a result, the participants in the experimental condition experienced greater difficulty when trying to identify person B.

Loftus et al., concluded that weapon focus would be a larger factor in real life, as the witness will be more aroused and is therefore likely to have increased attentional narrowing.

Loftus et al., Evaluation

+ Laboratory experiments are high in controls and therefore highly valid.

+ Reliability. As the experiment was replicated with the similar results, we can say that the experiment is high in reliability.

+ High Standardisation, the experiment is highly standardised, for example each slide was shown for exactly 1.5 seconds.

– Demand characteristics, as the students were either paid $3.50 or given extra credit for participating, they may have feel the need to act in a way which the experimenter would want.

– Ecological Validity, despite having concluded that the weapon focus phenomenon would be heightened in real life, no attempt was made to make the experiment true to life, thus we cannot say that the experiment is ecologically valid.

– Ethnocentrism, the study was only focused on students from Washington University.

 

Audio Podcast

References

1. Loftus et al., (1987) – Some Facts About “Weapon Focus”, Journal of Law and Human Behaviour 11 (1), 55–62

 

Further Reading

OCR A2 Psychology Student Unit Guide: Unit G543: Forensic Psychology (Student Unit Guides)