UNIVERSITY NEWS LAST UPDATED : 14 AUGUST 2017
In the latest entry of our I Am BCU Research Series, Dr Helen Wyler lays out her research into eyewitnesses, and the phenomena of the "misinformation effect".
For the police and the courts it is crucial that witnesses report their observations at a crime scene as accurately as possible. Yet it has been found that when people witness an event and later learn additional information about that event that is incorrect, they often include that incorrect information in their description of the event.
In psychological literature, this phenomenon is known as the misinformation effect. Such incorrect information can be conveyed through various channels such as the media, other witnesses, or the police. Witnesses who report misinformation can unintentionally obstruct criminal investigations.
The reasons why a witness reports misinformation are manifold and include elements such social pressure (‘That is what they want to hear from me’) and poor source memory (i.e. reporting the first thing that comes to mind without thinking about where it is remembered from). Understanding the exact reasons why misinformation is reported can help developing strategies to avoid or detect such errors during a police interview.
A scientific study was conducted to examine:
- the reasons why people report misinformation (which has implication as to how this could be handled in police interviews);
- whether these reasons differ depending on whether the misinformation concerns an important/central aspect of the event or a more peripheral one.
Participants first watched a short video and were then provided with two pieces of misinformation, one about a central aspect (e.g. perpetrator’s actions) of the event from the video and one about a peripheral aspect (e.g. an accomplice’s head wear). When later asked to answer questions about the video, some participants were warned that they may have been exposed to misinformation, which is assumed to discourage reporting the misinformation because of e.g. social pressure. Furthermore, participants were asked where they remembered specific pieces of information from, with the aim to nudge source memory.
We found that the warning considerably reduced the misinformation effect for the central aspect, whereas asking about the source of a memory was particularly helpful to identify reported misinformation for the peripheral aspect, although the effect could not be completely eliminated.
Overall, the findings suggest that (1) the reasons for reporting misinformation vary depending on how important something is to the witnessed event, and (2) that both a warning and asking where a specific piece of information is remembered from can be beneficial to reduce the misinformation effect.
In addition to understanding how to obtain accurate witness reports, it is also crucial to better understand how we can distinguish guilty and innocent suspects in an investigative interview. A British Academy/Leverhulme Small Research Grant has been awarded to the first author to explore possible ethnical differences in guilty and innocent suspects’ responses in an investigative interview.