Deception detection using a task switching paradigm : an event-related potential study

Existing methods of lie detection have insufficient accuracy or applicability in forensic settings. The present study aimed to determine whether behavioural and electrophysiological markers of task switching occur when individuals switch between lying and truth telling, as these markers could be used to develop a new method of lie detection, using a modified task switching paradigm. Sixteen participants (five male, aged 18-34) completed a sincerity switching paradigm in which they switched and repeated lying and telling the truth about whether objects were on a previously memorised list. They also completed a comparable traditional task switching paradigm, in which they switched and repeated making environmental and directional judgements about similar objects. In both paradigms, significant switch costs were observed, and a significant ERP negativity occurred at similar latencies in the 500-600 ms post-target interval, on switch relative to repeat trials in a mixed block. The results suggest switching between lying and truth telling does involve task switching processes, and it may be possible to develop a lie detector based on behavioural and electrophysiological markers of sincerity switching. More research is needed to define the conditions under which these markers occur, and to develop a paradigm appropriate for use in forensic settings.