The Operational Development and Empirical Testing of the Terrorist Radicalization Assessment Protocol (TRAP–18)

Abstract

The Terrorist Radicalization Assessment Protocol (TRAP-18) is a structured professional judgment instrument for threat assessment of the individual terrorist. It is a rationally derived theoretical model comprising eight proximal warning behaviors and 10 distal characteristics. Empirical research on the TRAP-18 is reviewed, including both nomothetic and idiographic studies of individual terrorists in both the United States and Europe. Mean interrater reliability is 0.895 (Cohen's kappa), ranging from 0.69 to 1.0. Evidence of criterion validity has been demonstrated, including usefulness of the instrument across various extremist ideologies (jihadism, ethnic nationalism, and single-issue), and its ability to discriminate between thwarted and successful attackers. The instrument appears to advance the domain recommendations of Monahan (2012, 2016) for the risk assessment of the individual terrorist. The TRAP-18 is further discussed as a threat assessment instrument for mental health clinicians. The limitations of the current research provide direction for further studies to assess its reliability and construct, discriminant, and predictive validity.

Visualizing the relationship among indicators for lone actor terrorist attacks: Multidimensional scaling and the TRAP‐18

“…In the case of a terrorist, it could be martyrs who have preceded him, an omniscient or omnipotent god, a movement leader, a religious figure, a political figure, or a relative who has also been radicalized. These fantasies are usually imbued with grandiosity and violence, and serve the goal to cleanse or purify the environment of apostates, infidels, unbelievers or contaminating “others” (Meloy, ). Both religious and secular persecutors can fill the bill.…”

“…The proximal warning behaviors (Meloy, Hoffmann, Guldimann, & James, 2011) were combined with proposed distal characteristics (Meloy & Yakeley, 2014) to construct the instrument (Meloy, 2017). Since its introduction in Meloy, Roshdi, et al, (2015), its psychometric properties have been studied in a variety of nomothetic and idiographic studies (see Meloy, 2018b for a detailed history of its origins and development).…”

Terrorism and mental illness: a pragmatic approach for the clinician

“…The TRAP-18 can inform the clinician's professional judgement and clinical decision-making in active case management or ongoing monitoring. Its developers report a mean interrater reliability of 0.895 (range 0.69–1.0) and good discriminant validity between thwarted and successful attackers (Meloy 2018).…”

Violent Attacks: What Do We Know? What Can We Do?

“…This reflects a shift from viewing terrorist attacks and mass shootings as stemming from a specific form of psychopathology, such as psychopathy, to viewing mass violence as the end result of a dynamic process that might be provoked by specific issues, such as a sense of grievance, mistreatment, or victimization, but not be acted on unless other factors, such as a desire for attention and fame, are present. In his article, for instance, Meloy (2018) outlines an approach to threat assessment using a structured, professional judgment instrument, the TRAP-18, which was developed based on a sophisticated integration of the empirical literature, theoretical conceptualizations of the dynamics involved in mass attacks, and realworld experience.…”

“…Among the variables associated with increased risk of violent action identified by Corner et al (2018), Lankford (2018), and Meloy (2018) are several that can be objectively examined during a psychological assessment. These include indications of psychosis, particularly a delusional disorder involving a fixation on a specific individual or cause; suicide potential and indifference to living; an exaggerated need for attention and desire for fame; and an identity organized around the perception of having been mistreated and victimized and the belief that retribution for these grievances is warranted and justified.…”