Eye witness testimony (EWT) is regularly a deciding factor for courts in the criminal justice system to ‘prove’ the guilt or innocence of the criminally accused. However, inaccuracies in EWT are common, accounting for about 75% of incorrect convictions later found to be innocent using DNA evidence.
One factor that could negatively influence EWT accuracy is misleading information - i.e. any information that ‘leads’ you into giving a particular response, as opposed to a necessarily accurate response. The two types of misleading information are:
Below are two examples of studies conducted by Elizabeth Loftus (a key researcher in EWT) that provide evidence of these sources of misleading information.
Loftus and Palmer (1974)
Participants were shown videos of traffic collisions, and then given a questionnaire to test their immediate recall of the videos’ events.
Among the questions was one critical question, “About how fast were the cars going when they hit each other?”. One group was asked this version, but four other groups were given versions that replaced “hit” with either “contacted”, “collided”, “bumped” or “smashed”. The results found that vehicle speed estimates were fastest on average for participants given the “smashed” version, and slowest for participants given the “contacted” version, suggesting that an eye witness’ immediate recall of an event could be skewed by leading questions.
Participants were shown a video of a lecture being disrupted by 8 demonstrators, then later completed a questionnaire containing a critical question in one of two versions: “was the leader of the 4 demonstrators male?” or “was the leader of the 12 demonstrators male?”.
After a week delay, further questions were posed to participants, including one asking how many demonstrators were in the video. The mean number estimated by participants asked earlier about the group of 4 demonstrators was significantly lower than those asked about the group of 12, supporting the claim that post-event information can negatively influence memory recall accuracy.
Evaluation of EWT misleading information research
- There is a large base of evidence suggesting that misleading information can lead to EWT inaccuracy, which has raised awareness that the criminal justice system cannot always rely on EWT as a basis for [sometimes incorrect] convictions.
- Highlighting misleading information as a negative factor in EWT has led to new techniques designed to improve memory retrieval, such as the cognitive interview developed by Geiselman and colleagues.
- Laboratory experiments may have low external validity (i.e. bear little relation to a real court scenario); participants in research may be more likely to anticipate truthful information from experimenters, whereas eye witnesses in court cases may anticipate being subject to leading arguments as guilt/innocence is advocated (and thus identify/attempt to avoid being misled).
- A further realism pitfall - watching a video is arguably less emotionally arousing than witnessing real incidents, and some evidence suggests that emotional arousal can increase can improve the accuracy of EWT.
- We cannot be certain whether or not misleading information actually influences the memory ‘trace’ itself; it could just be demand characteristics driving changes in recall (i.e. participants’ behaviour may be affected by how they perceive the purposes of the experiment).
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