Applying Hierarchy of Expert Performance (HEP) to investigative interview evaluation: strengths, challenges and future directions.

The purpose of this paper is to systematically examine the research literature on the decision of expert interviewers within the theoretical framework of the Hierarchy of Expert Performance (HEP). After providing an overview of the HEP framework, existing research in the investigative interviewing at each of the eight levels of the HEP framework is reviewed. The results identify areas of strength in reliability between experts' observations (Level 2) and of weakness in reliability between experts' conclusions (Level 6). Biases in investigative interview experts' decision making is also revealed at biasability between expert conclusions (Level 8). Moreover, no published data are available in reliability within experts at the level of observations (Level 1) or conclusions (Level 5), biasability within or between expert observations (Level 3 and 4) and biasability within expert conclusions (Level 7). The findings highlight areas where future research and practical endeavour are much needed for the investigative interview.