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Forensic psychology
Forensic psychology

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1 Identification procedures

Figure 1

While facial composites (such as the E-FITs you saw last week) may have no evidential value, other identification evidence may be used in court as proof that the accused person is guilty, or alternatively to eliminate a suspect from an investigation.

There are different methods for obtaining identification evidence, however, and which of them is considered a lawful means of identification may vary from country to country.

In some countries, where communities are small and widely spaced, it is often impossible for the police to put on a live identification parade – one in which the witness views the suspect and foils (people who look like the suspect) when they are physically present. Instead, identifications can be made from photo-arrays, where the witness sees a photograph of the suspect and a number of foils, or video parades, where video images of the suspect and foils are shown. Up until 2003, live parades were the most common eyewitness identification method used in the UK, but after 2003 video parades have become the standard technique. In the USA, photo arrays tend to be the most used procedure.

Research conducted in the laboratory has pointed to three factors (all are system variables) that may influence identification accuracy in live, video and photo-based identification parades. They are:

  • the instructions given to the eyewitness – such as telling the witness that the perpetrator may or may not be present
  • the specific procedure used to show the faces – for example whether the faces are seen altogether or one after the other
  • the structure of the identification parade – including how similar the faces in the parade are to one another.

First, and as you saw in Week 1, many studies have shown that indicating through questions that the perpetrator ‘is in’ the line-up, rather than saying that they ‘may or may not be present’, increases the rate of mistaken identification (e.g. Cutler et al., 1987).