: Brain scans that claim to be able to determine whether a criminal is guilty of a crime can be fooled.
British research has now shown that people can intentionally suppress incriminating memories and thereby avoid detection in brain activity guilt detection tests. Brain activity guilt detection testsare promoted as accurate and reliable measuresfor establishing criminal culpability.
The University of Cambridge says such tests, which are commercially available in the US and are used by law enforcement agencies in 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, 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.
An international team of psychologists from the universities of Cambridge, Kent and Magdeburg as well as the Medical Research Council has now shown that some people can intentionally and voluntarily suppress unwanted memories. Dr Zara Bergstrom, expert ofcognitive psychology at the University of Kent and principal investigator on the research said "Our research has shown that this assumption that brain scans can pinpoint guilt is not always justified. Using these types of tests to say that someone is innocent of a crime is not valid because it could just be the case that the suspect has managed to hide their crime memories."
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." During the study, 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 Michael Anderson from the Medical Research Council Cognition and Brain Sciences Unit in Cambridge said "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."
