Making a case: INTERVIEWING WITNESSES

Interviewing Witnesses is a key part of making a case because it enables the police to gather information from the people who were there, but it's not the most reliable way. Thus, research into this area - so long as it's reliable and valid - can have really valuable applications... or it can be used in a pretty unethical way.

Recognising faces

Misidentification of a suspect from an eyewitness is the most important factor contributing to wrongful convictions, so it's really important that psychologists research into how faces are recognised. Studies have suggested that a lot of factors contribute to how easily or successfully faces can be recognised, such as perspective, lighting, the witness's mood, and then more obvious factors such as duration of time the suspect was seen for, familiarity and how far away they were. Many cases of mistaken identity have made this a prominent field of study in forensic and cognitive psychology. 

Study: Bruce et al. conducted 3 laboratory experiments into the relative importance of external and internal features in facial recognition. The first experiment used a sample of 30 mixed age participants from Stirling University (teachers and students). They were shown 10 target photographs of male celebrities, with 40 facial composites, and asked to match the photographs to the composites. One group was given full composites, a second group was given composites with only internal features, and another group were given only external composites. In the second experiment, 48 undergraduates were split into four groups, and all were asked to complete the task of selecting the right celebrity being shown to them in a composite. The conditions were split into easy and hard, as well as internal or external composites given. The third experiment was somewhat similar to experiment one, except familiarity of the faces was also measured through a naming task. The first experiment showed that external and full composites were accurately matched 33% of the time, whilst internal feature composites were matched at 19.5% accuracy. Experiment 2 found the external composites to be matched correctly 42% of the time, with internal features matched correctly 24% of the time. The third experiment showed little difference in accuracy when faces were thought to be familiar with the participant. Thus, this experiment suggested that faces are processed holistically and that internal features do not significantly appear to contribute to facial recognition. Furthermore, it was suggested that familiarity may not be a significant factor in contributing to accurate identification from internal feature composites. 

Influencing factors

When interviewing witnesses, there are a lot of influencing factors that affect the reliability and validity of recall. There are situational and dispositional factors, and Loftus and Palmer's study on eyewitness testimony (AS study) showed that leading questions and bias can influence recall too. One main influence in whether faces can be recognised is thought to be weapon focus effect; the idea that if a weapon is present in a crime, then people will spend more time looking at the weapon than the offender because they feel threatened, and thus will be less able to identify the offender or give other details. 

Study: Loftus et al. conducted a laboratory experiment to test the theory of weapon focus effect. The study used a sample of 36 University of Washington students who were split into a control group and the experimental group. Both groups were shown slides of a queue in Taco Bell. All slides were the same except 1 critical slide, which showed the second customer either pulling a gun on the cashier (experimental condition) or handing them a cheque (control). The participants were then asked to fill out questionnaires, where the critical question asked them to identify the second customer in the queue. The results appeared to support the theory; eye fixation was longer on the gun than the cheque by one second, and 39% of the control correctly identified the offender, whilst only 11% of the experimental condition did. 

Cognitive interviewing techniques 

I've already created a post on CIT, so I'll just list the steps below:

- Report everything

- Context reinstatement

- Recall in different order

- Recall from different perspective

Study: Fisher et al. conducted a field experiment which aimed to field test the cognitive interview. A sample of 16 experienced detectives from Florida were used in the sample. All were at first asked to tape record various interviews with victims of minor theft (the detectives were experienced in this sort of crime), and were then assigned to either the experimental condition or control condition. The experimental condition (7 of the detectives) received four one-hour sessions of CIT training. All were then asked to tape record several more interviews which were then judged by independent judges. The results were positive; 6 out of 7 CIT trained detectives recorded more information, and they recorded 47% more than they did pre-training. They also recorded 63% more compared to the control group, suggesting CIT is effective and easy to provide.