Detection of deception using fMRI: better than chance, but well below perfection

Functional brain imaging has been considered a new and better technique for the detection of deception. The reasoning is that there is a neural locus or circuit for lying that is sensitive, specific, generalizable across individuals and measurement contexts, and robust to countermeasures. To determine the extent to which the group results predicted lying at the level of the individual, we reanalyzed data on 14 participants from a study that had previously identified regions involved in lying (thus satisfying the criterion for sensitivity). We assessed the efficacy of functionally determined brain regions based on the lie-truth contrast for N-1 participants to detect deception in the Nth individual. Results showed that no region could be used to correctly detect deception across all individuals. The best results were obtained for medial prefrontal cortex (mPFC), correctly identifying 71% of participants as lying with no false alarms. Lowering the threshold for a response increased hits and false alarms. The results suggest that although brain imaging is a more direct index of cognition than the traditional polygraph, it is subject to many of the same caveats and thus neuroimaging does not appear to reveal processes that are necessarily unique to deception.