Is observation of non-verbal behaviours truly valuable in the detection of people with mal-intent? Sharon Weinberger says researchers are increasingly dubious of the science behind programs such as the Screening Passengers by Observation Technique (SPOT). But the lack of proven results has not stopped other countries implementing similar aviation-security programmes. "Simply put, people (including professional lie-catchers with extensive experience of assessing veracity) would achieve similar hit rates if they flipped a coin," Weinberger quotes from an expert report.