Objective: This paper aims to develop diagnostic criteria for factitious disorder (FD) and a heuristic for research by creating standards for delineating criterion groups.Method: Both FD and malingering are conceptualized within a rubric of illness-deception. The history of FD research was compared to the research history on malingering. Differences in the measurement of these constructs were described. The potential utility of performance validity tests (PVTs) and symptom validity tests (SVTs) in FD is discussed in light of successful applications in malingering. Methods for obtaining evidence for FD are delineated in a table of diagnostic criteria.Results: The comparison of FD and malingering research shows that the scientific measurement of malingering evolved rapidly with the introduction of forced-choice validity testing and cogent guidelines for the formation of criterion groups. Likewise, PVTs and SVTs hold promise as methods of measuring deceptive behavior in FD. The most salient differences between FD and malingering are understood to be matter of context/setting: malingering occurs in an external incentive context, while FD occurs in a medical/psychological context. Guidelines to assess FD are developed to fill the need for known-groups research.Conclusions: Evidence for FD, a form of illness-deception, can be obtained by using validity testing, which, together with careful clinical observation, allows for the development of probabilistic diagnostic criteria. Similar to the other form of illness-deception - malingering - these criteria can be used to form known groups for research.
Keywords: Factitious disorder; Munchausen; conversion disorder; illness-deception; malingering; validity testing.