SCAN as an investigative tool

Scientific content analysis (SCAN) is a technique that claims to enable the detection of deception in written statements. The underlying assumption is that statements of self-experienced events differ in several ways – such as liveliness and concreteness – from imaginary statements. It is used in many countries as an investigative tool. Nevertheless, little research on the reliability and validity of the SCAN technique is available. In this paper, two studies are presented. The first study focuses on the accuracy of SCAN to detect deception by three groups of raters with a different level of experience. This study shows a lack of validity of SCAN. Study 2 investigated the inter-rater reliability as a possible explanation for the poor validity results, and found little agreement between raters in identifying SCAN criteria. Overall, results indicate that the psychometric qualities of SCAN as an investigative tool is insufficient for use in police practice.