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People can ‘beat’ guilt detection tests by suppressing incriminating memories
Image credit: Department of Psychology "Dr Zara Bergstrom (right) and Dr Jon Simons (centre) examine the electrical brain activity of another of the paper's authors, Marie Buda (seated).
The study has shown that people can intentionally suppress incriminating memories and thereby avoid detection in brain activity guilt detection tests.
Such tests, which are commercially available in the United States and are used by law enforcement agencies in several countries, including Japan and India, are based on the logic that criminals will have specific memories of their crime stored in their brain. When presented with reminders of their crime, it was previously assumed that their brain would automatically and uncontrollably recognise these details. Using scans of the brain’s electrical activity, this recognition would be observable, recording a ‘guilty’ response.
However, research by an international team of psychologists from the universities of Cambridge, Kent and Magdeburg as well as the Medical Research Council, has shown that some people can intentionally and voluntarily suppress unwanted memories.
For the study, the researchers had participants conduct a mock crime. These people were later tested on their crime recognition while having their brain activity monitored using electroencephalography (EEG). Critically, when asked to suppress their crime memories, a significant proportion of people managed to reduce their brain’s recognition response and appear innocent.
If suspects can intentionally suppress their memories of a crime and evade detection, the research calls into question the reliability of brain activity guilt detection tests, and suggests careful consideration is needed before such evidence is introduced in criminal trials.
Dr Jon Simons, of the Department of Psychology at the University of Cambridge, added: “Our findings would suggest that the use of most brain activity guilt detection tests in legal settings could be of limited value. Of course, there could be situations where it is impossible to beat a memory detection test, and we are not saying that all tests are flawed, just that the tests are not necessarily as good as some people claim. More research is also needed to understand whether the results of this research work in real life crime detection.”
Dr Michael Anderson, Senior Scientist at the Medical Research Council Cognition and Brain Sciences Unit in Cambridge, commented: “Interestingly, not everyone was able to suppress their memories of the crime well enough to beat the system. Clearly, more research is needed to identify why some people were much more effective than others.”
Dr Anderson’s group is presently trying to understand such individual differences with brain imaging.Adapted from University of Cambridge News
Posted on 11/06/2013
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