Forensic Psychology For Dummies (37 page)
Read Forensic Psychology For Dummies Online
Authors: David Canter
Height:
Witnesses are often poor at judging heights, and as with age, the greater the difference in height between the offender and the eyewitness, the less accurate the estimate.
Witnesses have difficulty at judging the build of a person, with judgements being heavily influenced by clothing.
Witnesses’ descriptions of the style of clothing are usually reasonably accurate, but a description of the colour of the clothing is often less accurate.
Eyewitness identifications aren’t nearly as accurate and reliable as the public and the courts believe. As an example, an experiment was undertaken in which a person goes into a convenience store drawing attention to themselves by paying for their purchases all in pennies. Soon afterwards the salesperson views a photo spread and identifies the ‘customer’. The percentage of correct identifications in such exercises ranges from 34 to 48 per cent and the percentage of false identifications from 34 to 38 per cent. Even after quite a short interval, an eyewitness is as likely to be as incorrect as correct when attempting to identify strangers.
Eyewitnesses are most accurate when identifying someone from a familiar and similar situation to themselves.
The innocence project
Scary but horribly true! In 1999, in the US, eyewitness identifications led to 75,000 prosecutions. DNA is now offering a much more reliable way of identifying a suspect and shows just how dodgy many legal eyewitness identifications are. One study shows that of the 62 persons acquitted by DNA evidence, 52 had been imprisoned on the basis of faulty eyewitness identification. Researchers hold a growing belief that the majority of false convictions are due to mistaken eyewitness testimony.
Lack of relationship between confidence and accuracy
A witness talking with great confidence about what they can remember doesn’t mean that they’re being any more accurate in what they’re saying than someone who seems much less confident. There’s no evidence of a simple link between confidence and accuracy. Furthermore, confidence increases over time, especially if the witness is giving the same account to different people, and so any relationship between confidence and accuracy grows less and less.
Also, if a police officer confirms to a witness that what the witness says agrees with other facts known to the police, the witness’s confidence increases further, although the accuracy of what’s being said doesn’t.
A witness is more likely to recognise a person or event accurately if the happening was particularly memorable or striking. For example, you’re more likely to remember a person’s clothing, race or age if it stands out in contrast to that of other bystanders. Novel events, such as a ballerina tripping during a performance, or even more memorable, a politician admitting he’s made a mistake, are more readily noted and remembered because the event is so rare and unusual.
Assessing eyewitness accuracy
Mnemonics
, in which a memorable word is used to summarise a set of other facts, is a powerful aid to memory. Two colleagues of mine, Graham Wagstaff and Mark Kebbell, have created the mnemonic ADVOKATE to summarise the key factors influencing a witness’s ability to remember the details of an event:
mount of time under observation – the longer a witness observes an event, the better the event is remembered.
istance of the witness from the person or event – being closer to the person or the event means that a witness is likely to be better at storing and remembering details.