University of Virginia School of Law
Public Law and Legal Theory Working Paper Series 2011- 34
The Individual Risk Assessment of Terrorism
University of Virginia School of Law
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Running head: INDIVIDUAL RISK ASSESSMENT OF TERRORISM 1
Psychology, Public Policy, and Law, in press.
The Individual Risk Assessment of Terrorism
University of Virginia
John Monahan, School of Law, University of Virginia.
This research was supported by the Department of Defense, in contract with ViaGlobal
Solutions LLC. The opinions expressed in this article are mine alone. I thank Susan Brandon,
Deborah Loftis, Reid Meloy, and the participants at the University of Virginia’s Working
Conference on the Risk Assessment of Terrorism for their comments on the ideas developed
here. I am grateful to Lynn Boyter and Patrick Fleming for arranging that meeting. Much of this
research was conducted while I was Professor in Residence at the New York University School
of Law, for which I am indebted to Dean Richard Revesz and Professor James Jacobs.
Correspondence concerning this article should be addressed to John Monahan, School of
Law, University of Virginia, 580 Massie Road, Charlottesville, VA 22903-1789. E-mail:
© (2012) American Psychological Association
Running head: INDIVIDUAL RISK ASSESSMENT OF TERRORISM 2
I attempt to identify the central conceptual and methodological challenges that must be overcome
if the risk assessment of terrorism is to make the same progress that in recent years has
distinguished the risk assessment of other forms of violence. Four principal conclusions are
offered. First, clarity from the outset on what is being assessed—the risk of terrorism in the
aggregate, or of specific types of terrorism, or of specific phases in the process of becoming a
terrorist, or of specific roles in terrorist activity—is a prerequisite to progress in research.
Second, one current approach to the risk assessment of more common violence (e.g., assault)—
the approach known as structured professional judgment—usefully may be applied to the risk
assessment of terrorism. However, given that many known risk factors for common violence are
in fact not risk factors for violent terrorism, the substantive content of any instrument to assess
the risk of terrorism will be very different from the substantive content of current instruments
that address common violence. Third, since there is little existing evidence supporting the non-
trivial validity of any individual risk factors for terrorism, the highest priority for research should
be the identification of robust individual risk factors. Promising candidates include ideologies,
affiliations, grievances, and “moral” emotions. Finally, it is highly unlikely that an instrument to
assess the risk of terrorism can be validated prospectively. An infrastructure for facilitating
access to known groups of terrorists and non-terrorists from the same populations may be crucial
for conducting a program of scientifically rigorous and operationally relevant research on the
individual risk assessment of terrorism.
Key words: risk assessment, risk factors, terrorism, validation, violence
Running head: INDIVIDUAL RISK ASSESSMENT OF TERRORISM
On November 5, 2009, yelling “Allahu Akbar,” U.S. Army Major Nidal Hasan killed 13
people and wounded 32 others at Fort Hood, Texas. All but two of the victims were military
personnel. In response to this shooting, Defense Secretary Robert M. Gates commissioned an
Independent Review to identify and address possible deficiencies in Department of Defense
(DoD) practices “related to force protection and identifying DoD employees who could
potentially pose credible threats to themselves or others.” Among the conclusions of this review,
titled Protecting the Force: Lessons from Fort Hood (2010b), was the following:
Academics have been developing violence risk assessment tools that the Department of
Defense could employ or emulate. For example, the MacArthur Violence Risk
Assessment Study produced a model to predict risk of violence among patients recently
discharged from psychiatric facilities. Software incorporating this model was quite
successful in its assessment of whether patients fell into a low- or high-risk group for
violence (Monahan et al, 2005). This software, called Classification of Violence Risk, is
available for use with acutely hospitalized civil patients, and suggests that the
development of tools for other populations may be worth pursuing... A full academic
literature review would reveal other tools like these that the Department of Defense might
use in part or in whole. The Department of Defense could also sponsor the development
of [its own] comprehensive risk assessment tool (pp. D4-5).
In this article, I attempt to identify the conceptual and methodological impediments that
must be overcome in order to conduct scientifically valid and operationally relevant research on
the individual risk assessment of terrorism. Part I briefly describes two of the principal contexts
in which an individual’s
risk of terrorism is assessed: when making decisions about the
detention of accused or adjudicated terrorists, and when selecting and retaining military or
civilian contract employees of the Department of Defense. Part II provides an account of existing
approaches to the individual risk assessment of forms of violent behavior more common than
terrorism (e.g., assault), and considers whether these approaches can be generalized to violent
terrorism. Part III surveys existing evidence of what constitute individual risk factors for
terrorism. Part IV—the heart of the article— elaborates on four of the most critical conceptual
and methodological challenges that must be surmounted if progress in this area is to be made: the
heterogeneity of what is meant by “terrorism,” the optimal degree of structuring risk
assessments, the need for more robust risk factors, and the creation of an infrastructure for
validating these risk factors.
Throughout the article, I adopt the definition of terrorism used by the Department of
Defense (2010a): “The calculated use of unlawful violence or threat of unlawful violence to
inculcate fear, intended to coerce or to intimidate governments or societies in the pursuit of goals
that are generally political, religious, or ideological.”
This article concerns an individual’s risk of terrorism. One can also assess more macro-level forms of risk, e.g., the
risk that a given type of terrorist act will occur in a given country over a given time period (LaFree & Ackerman,
2009). These are important forms of risk assessment, but they are not the form of risk assessment dealt with here. In
addition, this paper deals with assessments of terrorism risk, and not with the communication of those assessments
to decision makers (Heilbrun, Wolbransky, Shah, & Kelly, 2010; Fischhoff, 2011).
Running head: INDIVIDUAL RISK ASSESSMENT OF TERRORISM 4
Part I: Two Contexts for the Risk Assessment of Terrorism
Decisions requiring an estimate of an individual’s risk of terrorism arise in many aspects
of national security (Department of Defense, 2010b). To facilitate discussion, I focus on two of
the most frequent uses of terrorism risk assessment. The first use concerns decisions regarding
the detention of individuals prior to the adjudication
of a charge of having committed a terrorist
act, or the release from detention of individuals adjudicated as having committed such an act.
Terrorist risk assessment in detention decisions might be seen as reflecting the perspective of
terrorism as crime (Kruglanski, Crenshaw, Post, & Victoroff, 2008), since it corresponds closely
to the most frequent uses of violence risk assessment in the American criminal justice system:
the pre-trial detention of defendants accused of crime, and the release on parole of prisoners
convicted of crime (e.g., Monahan & Walker, 2010, Chapter 5; 2011).
In addition to informing decision making on detention, risk assessments of terrorism play
an important role in a second context: employment decisions made by government agencies—
what might be termed terrorism as workplace violence (Barling, Dupre, & Kelloway, 2009;
White & Meloy, 2010). The workplace violence perspective applies to the selection and retention
of members of the military itself (e.g., Fort Hood’s Major Hasan), as well as to the selection and
retention of civilian contract employees. It is often referred to as the identification of “insider”
terrorists (Bulling & Scalora, 2008).
Decisions on Detention
Consistent with the terrorism as crime perspective, the Department of Defense (2006), in
a document titled Medical Program Support for Detainee Operations, defines “behavioral
science consultants” as “[h]ealth care personnel qualified in behavioral sciences who are assigned
exclusively to provide consultative services to support authorized law enforcement or intelligence
activities” (p. 2), and states that these consultants “may advise command authorities responsible for
determinations of release or continued detention of detainees of assessments concerning the
likelihood that a detainee will, if released, engage in terrorist, illegal, combatant, or similar activities
against the interests of the United States” (p. 9). Similarly, Kennedy, Borum, and Fein (2011, p. 70)
have recently noted:
A relatively small but growing number of psychologists have assumed professional roles and
duties that focus primarily on supporting CI [Counterintelligence] and CT [Counterterrorism]
operations. These psychologists are not assigned to these roles for purposes of providing
health-related services and sometimes describe their role or themselves as operational
psychologists to emphasize this distinction... [These] psychologists may conduct risk
On March 7, 2011, President Obama issued an Executive Order titled “Periodic Review
of Individuals Detained at Guantanamo Bay Naval Station Pursuant to the Authorization for Use
For the purpose of improving empirical research on the risk assessment of terrorism, it is not necessary to take a
position on the relative legal merits of criminal trials versus military commissions to adjudicate guilt for the
commission of terrorist acts (Vladeck, 2010; Wittes, 2010).
Running head: INDIVIDUAL RISK ASSESSMENT OF TERRORISM 5
of Military Force.” The Order stated that “Continued law of war detention is warranted for a
detainee subject to [p]eriodic review… if it is necessary to protect against a significant threat to
the security of the United States.”
Little published information is available on how these assessments of “significant threat”
are conducted (Felter & Brachman, 2007; Denbeaux & Denbeaux, 2008). Savage, Glaberson
and Lehren (2011) claim that at one point detainees were assessed as having a “high risk,” a
“medium risk,” or a “low risk” of terrorism, but that this has recently changed:
In 2009, a task force of officials from the government’s national security agencies re-
evaluated all 240 detainees then remaining at the prison [i.e., Guantanamo Bay, Cuba].
They vetted the military’s assessments against information held by other agencies, and
dropped the “high/medium/low” risk ratings in favor of a more nuanced look at how each
detainee might fare if released, in light of his specific family and national environment.
But those newer assessments are still secret and not available for comparison.
In addition to the lack of descriptive information on the current status of assessing
terrorism risk in the context of decision making regarding detention, the validity of current risk
assessment methods is unclear. The most recent estimate by the Office of the Director of
National Intelligence (December 2010) is that 150 of the 598 detainees who have been released
from Guantanamo Bay (25 percent) are false negatives, i.e., they were subsequently “confirmed
or suspected of reengaging in terrorist or insurgent activities” (p. 1).
This estimate, however, is
highly contested. For example, Bergen, Tiedemann, and Lebovich (2011), writing in Foreign
Policy, claim that “the true rate for those [released detainees] who have taken up arms or are
suspected of doing so is more like 6 percent.”
Decisions on Employment
Individual risk assessment of U.S. military personnel is discussed in detail in Protecting
the Force: Lessons from Fort Hood (2010b). The most pertinent of the findings from this report
is that “DoD programs, policies, process, and procedures that address identification of indicators
for violence are outdated, incomplete, and fail to include key indicators of potentially violent
behaviors” (p. 11). The report recommends that the Department of Defense “[d]evelop a risk
assessment tool for commanders, supervisors, and professional support service providers to
determine whether and when DoD personnel present risks for various types of violent behavior”
From a workplace violence perspective, the selection and retention of DoD civilian
contract employees has received much less attention than the selection and retention of military
The Executive Order is available at http://www.whitehouse.gov/the-press-office/2011/03/07/executive-order-
“Confirmed” is defined in the report as “a preponderance of information identifying a specific former GTMO
detainee [i.e., a person who had been detained at the U. S. Naval Base at Guantanamo Bay, Cuba] as directly
involved in terrorist or insurgent activities.” “Suspected” is defined as “plausible but unverified or single-source
reporting indicating a specific former GTMO detainee is directly involved in terrorist or insurgent activities."
Appended to both definitions is the statement that “engaging in anti-U.S. statements or propaganda does not qualify
as terrorist or insurgent activity.”
Running head: INDIVIDUAL RISK ASSESSMENT OF TERRORISM 6
personnel. By way of background, since the Revolutionary War—when General Washington
hired civilians to drive wagons and to supply food to the Continental Army—the U.S. military
has relied on civilian contractors. What has changed drastically over the centuries is the extent of
this reliance. During the Revolution, one contractor was hired for every six uniformed members
of the military. Today, there is approximately one contractor for each uniformed member of the
military (Commission on Wartime Contracting in Iraq and Afghanistan, 2009). As a
representative of the Department of Defense recently testified, “We’re simply not going to war
without contractors” (Commission on Wartime Contracting in Iraq and Afghanistan, 2011, p.
18). These contract employees perform a wide range of services. In Iraq in 2010, contractors
performed two-thirds of all base support functions (e.g., food preparation, laundry, and grounds
maintenance). Importantly, they also provided 12 percent of all security services, including
armed security services (Schwartz, 2010).
The National Research Council (2010, p. 7) has noted in this regard that “many of the
support services that historically were provided by army members are now provided by locals.
So now it is important to be able to tell—with most of the people involved speaking a foreign
language—which people can be trusted enough to be let onto the base on a regular basis.”
How is the risk of terrorism by DoD contract employees or potential contract employees
currently assessed? Contractors who are U.S. citizens are required to undergo a standard
computerized background check of federal records (e.g., arrest records from the FBI and
employment records from the Office of Personnel Management). However, the DoD has not
established procedures to apply this background check requirement to foreign nationals—who
constitute 80 percent of all contract employees (Commission on Wartime Contracting in Iraq and
Afghanistan, 2011)—and “large numbers of people who gain access to our facilities are not
vetted at all under current procedures” (Department of Defense, 2010b, p. 14).
The reason for not establishing vetting procedures is readily apparent. Given that the FBI
and other U.S. sources have only limited data on foreign national contractor personnel—who
may have spent minimal if any time in the United States—and also given “the inconsistent
quality of criminal and employment records from one country to another” (Government
Accountability Office, 2009, p. 15), background screening is often not a realistic possibility. For
example, neither Iraq (Government Accountability Office, 2006), nor Afghanistan (U.S. Institute
of Peace, 2006) appears to have working a computerized system of criminal record keeping.
Since U.S. records are often inapplicable to local nationals, and host country records are
often nonexistent, unstructured interviews are often used to assess the risk of terrorism presented
by potential contract personnel (Government Accountability Office, 2006). However, a report of
the U.S. Senate Armed Services Committee (2010) provides evidence that current strategies for
terrorism risk assessment among DoD contractors are ineffective. For example, the Committee
found numerous instances of “private security contractors funneling U.S. taxpayers’ dollars to
Afghan warlords and strongmen linked to murder, kidnapping, bribery, as well as Taliban and
other anti-Coalition activities” (p. i).
Indeed, the Commission on Wartime Contracting in Iraq and Afghanistan (2011, p. 73) reported that “During a
March 2011 trip to Afghanistan, experts told the Commission that extortion of funds from U.S. construction projects
Running head: INDIVIDUAL RISK ASSESSMENT OF TERRORISM 7
Part II. Approaches to the Individual Risk Assessment of Common Violence and Their
Application to Violent Terrorism
How is the risk of violence currently assessed for types of violence other than terrorism?
Here, I give an overview of general approaches to the risk assessment of what might be called
“common violence”—such as the FBI violent index crimes of murder, rape, robbery, and
assault—in the criminal justice system (e.g., in the pre-trial detention and parole decision making
contexts described earlier as the terrorism as crime perspective) as well as in the mental health
system (e.g., in decisions regarding the civil commitment of people who are mentally ill and
believed to be “dangerous to others,” or who qualify as “sexually violent predators”) (Monahan,
Much that follows in terms of the creation of a research agenda on the risk assessment of
terrorism flows from the definition of risk assessment that one chooses. The definition of risk
assessment given by Kraemer, Kazdin, Offord, Kessler, Jensen, & Kupfer (1997) is the one I have
found most useful: “The process of using risk factors to estimate the likelihood (i.e., probability)
of an outcome occurring in a population.” Importantly, Kraemer et al (1997) define a risk factor
simply as any variable that (a) statistically correlates with the outcome (in this case, violence),
and also (b) precedes the outcome in time. There is no implication in this definition that the risk
factor in any sense “causes” the occurrence of the outcome.
and transportation contracts is the insurgent’s second-largest funding source” (with the drug trade being the largest
It is important to clearly differentiate the use of risk factors to predict behavior from what is commonly (and
always pejoratively) referred to as “profiling.” “Profiling” is defined in the Oxford English Dictionary (2011) as
“selection for scrutiny by law enforcement officials, etc., based on superficial characteristics (as ethnic background
or race) rather than on evidentiary criteria; esp. = racial profiling.”
None of the potential risk factors for terrorism considered here concern ethnic background, race, or other
“superficial characteristics.” None concern “scrutiny by law enforcement officials, etc.,” of groups in the general
population, either domestic or foreign (see, in general, Kennedy, Borum, & Fein, 2011).
It would be disingenuous not to acknowledge that there are definitions of risk more nuanced than the one given
here. For example, Hart (2009, p. 145) states:
The concept [of risk] is multi-faceted, referring to the nature of the hazard, the likelihood that the hazard
will occur, the frequency or duration of the hazard, the seriousness of the hazard’s consequences, and the
imminence or duration of the hazard. The concept of risk is also inherently dynamic and contextual, as
hazards arise and exist in specific circumstances.
See Hart and Logan (in press) for an account of “formulating violence risk.” Following Heilbrun (1997), however, I
believe that risk assessment and risk reduction are often most efficiently pursued as separate rather than integrated
tasks (Monahan, Steadman, Silver, Appelbaum, Robbins, Mulvey, Roth, Grisso, & Banks, 2001). On the reduction
of terrorism risk (sometimes called “de-radicalization” or “disengagement”) see Kruglanski, Gelfand, & Gunaratna
(2010) and Horgan & Braddock (2010). This paper considers only risk assessment and not risk reduction, which, as
Hart (2009) states, indeed necessitates an understanding of what Kraemer et al (1997) refer to as “causal” risk
Running head: INDIVIDUAL RISK ASSESSMENT OF TERRORISM 8
Approaches to the Risk Assessment of “Common” Violence
Many accounts of violence risk assessment rely on Paul Meehl’s (1954) canonical
distinction between “clinical” and “actuarial” (sometimes called “statistical”) prediction. In
recent years, however, many risk assessment instruments have been developed that are not
adequately characterized by a simple clinical-actuarial dichotomy. Rather, the risk assessment
process now exists on a continuum of rule-based structure, with completely unstructured
(“clinical”) assessment occupying one pole of the continuum, completely structured (“actuarial”)
assessment occupying the other pole, and several forms of partly-structured and partly-
unstructured assessment lying between the two.
Skeem and Monahan (2011) in this regard have argued that the violence risk assessment
process might usefully be seen as having four components: (a) identifying empirically-valid risk
factors, (b) determining a method for measuring (“scoring”) these risk factors (c) establishing a
procedure for combining scores on the risk factors, and (d) producing a final estimate of the
likelihood that violence will occur. It is possible to array five current approaches to violence risk
assessment according to whether the approach structures (i.e., specifies rules for generating)
none, one, two, three, or all four components of this process.
Approach 1: Unmodified clinical risk assessment.
Completely “clinical” risk assessment structures none of the components of the risk
assessment process. The clinician selects, measures, and combines risk factors, and produces a
final estimate of violence risk, as his or her clinical experience and professional judgment
indicate. There are no explicit rules to structure these decisions. Different risk factors may be
used for different individuals.
Approach 2: Modified clinical risk assessment.
Performing a violence risk assessment by reference to a standard list of risk factors that
either have been found by research to be empirically valid, or are part of “received wisdom
derived from practice in the field” (Appelbaum & Gutheil, 2007, p. 56), structures one
component of the process. It identifies which risk factors the clinician should attend to in
conducting his or her assessment. But standard lists of risk factors do not go further and specify a
method for measuring the risk factors on the list.
Approach 3: Structured professional judgment.
Approaches to violence risk assessment that structure two components of the process—
the identification and the measurement of risk factors—are often called “structured professional
judgment.” For example, in the HCR [Historical-Clinical-Risk Management]-20 (Webster,
Douglas, Eaves, & Hart, 1997) risk assessment instrument, twenty risk factors are listed, and
each risk factor is scored 0 if it is absent in the case being assessed, 1 if it is possibly present or
present to a limited extent, and 2 if it is definitely present. Structured professional judgment
instruments, however, do not go further and specify how the individual risk factor scores should
be combined in clinical practice to yield a total score. As Webster et al (1997, p. 22) have stated:
“it makes little sense to sum the number of risk factors present in a given case... [Rather,] it is
Running head: INDIVIDUAL RISK ASSESSMENT OF TERRORISM 9
both possible and reasonable for an assessor to conclude that an assessee is at high risk for
violence based on the presence of a single risk factor,” such as a direct threat to kill.
Approach 4: Modified actuarial risk assessment.
Approaches to risk assessment that structure three components of the process—the
identification, measurement, and combination of risk factors—are illustrated by the
Classification of Violence Risk (COVR) actuarial software (Monahan et al, 2005), mentioned in
the DoD report Protecting the Force (2010b). Those who developed this instrument do not
recommend that the final estimate of the likelihood of violence reflect only the combined scores
on the assessed risk factors, however. Given the possibility that rare factors influence the
likelihood of violence in a particular case—and that, precisely because such factors rarely occur,
they will never appear on any actuarial instrument—a clinical review of the risk estimate
produced by the actuarial software is advised.
Approach 5: Unmodified actuarial risk assessment.
The best known instrument that structures all four of the components of the violence risk
assessment process is the Violence Risk Appraisal Guide (VRAG) (Quinsey, Harris, Rice, &
Cormier, 2006). This instrument not only structures the identification, measurement, and
combination of risk factors, it also specifies that once an individual’s violence risk has been
actuarially estimated, the risk assessment process is complete. That is, there should be no clinical
review of the actuarial estimate. As Quinsey et al have stated, “What we are advising is not the
addition of actuarial methods to existing practice, but rather the replacement of existing practice
with actuarial methods” (p. 197).
Of the five approaches, the first (“unmodified clinical”) has some, but very limited,
empirical support (Lidz, Mulvey, & Gardner, 1993). As Mossman (1994) concluded in an
influential review, “representative data from the past two decades suggests that clinicians are able
to distinguish violent from nonviolent patients with a modest, better-than-chance level of
accuracy” (p. 790).
No research systematically compares the validity of all the approaches to risk assessment
described above. Relevant data are available, however, on approaches that structure two or
more components. These data provide little evidence that one validated instrument predicts
violence significantly better than another. In a meta-analysis of 28 studies that controlled for
methodological variation, Yang, Wong, and Coid (2010) concluded that in terms of their
predictive value, nine well-known risk assessment instruments were largely “interchangeable.”
The same judgment was reached by McDermott, Dualan, and Scott (2011).
Why might different instruments perform equally in predicting violence? One possible
explanation is that they tap—albeit in different ways—shared dimensions of risk, despite their
varied items and formats (Skeem & Monahan, 2011). For example, Kroner, Mills, and Reddon
(2005) factor analyzed a number of well-validated instruments and concluded that the
instruments assess four overlapping dimensions of violence risk: (a) criminal history, (b) an
irresponsible lifestyle, (c) psychopathy and criminal attitudes, and (d) substance abuse-related
Running head: INDIVIDUAL RISK ASSESSMENT OF TERRORISM 10
Can Approaches to the Risk Assessment of “Common” Violence Be Generalized to the Risk
Assessment of Terrorism?
The question of whether existing approaches to the risk assessment of common
violence—or any subset of these approaches—can be generalized to the risk assessment of
terrorism is the subject of a lively debate in two fields: criminology and forensic psychology. For
example, the criminologists LaFree and Dugan (2004) compare research on terrorism to research
on violence and crime more broadly. They note five conceptual similarities between the two
“(1) the study of terrorism, like the study of crime, has been intensively interdisciplinary
…; (2) both terrorism and crime are social constructions…; (3) for both terrorism and
crime, there are major differences between formal definitions and how these definitions
are applied in actual practice…; (4) terrorism, like common crime, is disproportionately
committed by young males…; [and] (5) sustained levels of terrorism, like sustained
levels of crime, undermine social trust” (pp. 54-56).
LaFree and Dugan (2004) also note six conceptual differences between terrorism and
“(1) While terrorist activities typically constitute multiple crimes (e.g., murder,
kidnapping, extortion), for many nations, a specific crime of terrorism does not exist…;
(2) The response to common crime rarely moves beyond local authorities, whereas the
response to terrorism usually does…; (3) while those who commit common crimes are
usually trying to avoid detection, those who commit terrorism are often seeking
maximum attention and exposure…; (4) terrorism, unlike common crime, is typically a
means to broader political goals…; (5) terrorists are more likely than common criminals
to see themselves as altruists…; [and] (6) terrorists are more likely than common
criminals to innovate [i.e., more likely than common criminals to change their criminal
activities over time]” (pp. 57-60).
LaFree and Dugan believe that “many of the differences between terrorism and common
crime are no more challenging than differences between common crime and more specialized
crimes, such as youth-gang activity, organized crime, hate crime, or domestic violence” (p. 71).
Similarly, Rosenfeld (2003, p. 34) rejects the proposition that “terrorism is qualitatively different
from the forms of violence we [i.e., criminologists] study.”
In the field of forensic psychology, the applicability of existing approaches to violence
risk assessment to the context of terrorism has been challenged by Dernevik, Beck, Grann, Hoge,
and McGuire (2009a). They take the view that “findings from studies of mentally disordered
offenders and generally violent correctional samples may well not be relevant in relation to
predicting recidivistic offending in perpetrators of politically-motivated behavior” (p. 508) (cf
Gudjonsson (2009) and Dernevik, Beck, Grann, Hoge, & McGuire (2009b)).
Answering the question of whether existing approaches to the risk assessment of common
violence can be generalized to the risk assessment of terrorism requires first answering another
question: what are valid individual risk factors for terrorism?
Running head: INDIVIDUAL RISK ASSESSMENT OF TERRORISM 11
Part III: Individual Risk Factors for Terrorism: The Evidence
For over a decade—since September 11, 2001—the empirical research on terrorism has
focused strongly on Islamic (or jihadi) terrorism. Therefore, many of the potential risk factors for
individual terrorism described below were studied in an Islamic context (Victoroff & Kruglanski,
2009). Even in this context, however, “there has been little systematic study of the specific
relationship between… risk factors and aspects of terrorism. Such research is vital as a prelude to
any attempt to create useful risk assessment tools for terrorism” (Roberts & Horgan, 2008, p. 7).
Ten putative risk factors for terrorism have received the bulk of research attention.
To no one’s surprise, there seems to be a consensus across many studies that the mean
age of violent terrorists ranges from approximately 20 to approximately 29, with Middle Eastern
offenders at the lower end of that range, and Chechens at the higher end (Pape, 2005; Merari,
2005, 2010; Davis and Cragin, 2009), in part because of mean age differences in the general
populations from which terrorists emerge in different parts of the world.
Many studies also report that the great preponderance of terrorists are male (Atran, 2003;
McCauley & Segal, 1987; Bakker, 2006; Merari, 2005, 2010). However, LaFree and Ackerman
(2009, p. 351) note that “compared with gender variation for common crimes, there appears to be
greater gender variation for terrorism.” As an example of this variation, Pape (2005) reported
that percentages of women varied greatly across terrorist groups, with no women among the al
Qaeda terrorists to more than half women for the Chechens and Kurds. Women who engage in
terrorism are sometimes widows of men killed by government forces. This is sufficiently
common that female Chechen suicide bombers are colloquially known as Black Widows. Forst
(2008) points out that violent terrorism (e.g., detonating bombs) may require less upper-body
strength than many ordinary violent crimes (e.g., mugging). Women also may have a strategic
advantage in that they can get close to targets without receiving the same level of scrutiny as
men (Berko, Erez, & Globokar, 2010).
In addition to being young and male, the majority of terrorists appear to be unmarried
(Atran, 2003; Merari, 2005; Gartenstein-Ross & Grossman, 2009). In contrast to this
generalization, however, Sageman (2008) reported that three-quarters of the jihadi terrorists in
his study were married. Indeed, he found that many of his subjects married into terrorist
organizations. Men joining these organizations often were not fully trusted unless their wives
were daughters or sisters of other terrorists. LaFree and Ackerman (2009) caution that there is
relatively little good research on marriage and terrorism, and the research that exists often lacks
comparison groups of non-terrorists drawn from the same population. Merari (2010, p. 73),
studying suicide terrorism, notes that “the single status of almost all suicides may suggest that
single persons are more willing to volunteer for suicide missions. However, in the Palestinian
case, it has also usually been the policy of the organizations to refrain from recruiting married
persons for such missions.”
Running head: INDIVIDUAL RISK ASSESSMENT OF TERRORISM 12
While the empirical evidence tends to support, if only in a qualified manner, the existence
of widely-suspected correlations between terrorism and age, gender, and marital status, the
evidence thoroughly contradicts the common belief that terrorists are disproportionately of lower
social class (Atran, 2003; Krueger & Maleckova, 2002; McCauley & Segal, 1987; Victoroff,
2005). In terms of occupation, income, and educational level, terrorists appear to be largely
indistinguishable from the local population. Surprisingly, one recent study even found that
suicide bombers “were, on average, much better educated than the population from which they
emerged” (Merari, 2010, p. 74). As Pape (2005, p. 216) has observed, terrorists “resemble the
kind of politically conscious individuals who might join a grassroots movement more than they
do wayward adolescents or religious fanatics.” LaFree and Ackerman (2009, p. 353) note that
“an interesting and thus far largely untested proposition is that terrorists are disproportionately
drawn from well-educated middle-class individuals who are employed in positions that are lower
in status than those that might be warranted by their credentials.”
Major Mental Illness
The lack of any relationship between major mental illnesses such as schizophrenia or
bipolar disorder and terrorism may be the most frequently and uniformly replicated finding in the
field (McCauley & Segal, 1987; Kruglanski & Fishman, 2006; Silke, 1998; Taylor & Quayle,
1994; Merari, 2005, 2010; Post, 2007). Little has changed—at least regarding group-based
terrorists (see below)—in the three decades since Martha Crenshaw (1981) famously noted that
“the outstanding common characteristic of terrorists is their normality.”
Interestingly, a number of careful recent studies indicate that mental illness is heavily
implicated in violence and threatened violence against public figures (e.g., James, Meloy,
Mullen, Pathe, Farnham, Preston, & Darnley, 2010). These studies explicitly “[e]xcluded…all
cases, whether perpetrated by an individual or a group, that had a clear terrorism motivation”
(Hoffmann, Meloy, Guldimann & Ermer, 2011, p. 151; cf. Hoffman, 2006, p. 37). For example,
James, Mullen, Meloy, Pathe, Farnham, Preston, and Darnley (2007) report that among those
who attacked European politicians between 1990 and 2004, people with a serious mental illness
were responsible for almost all of the fatal and seriously injurious attacks.
Pape’s (2005, p. 210) influential study of suicide terrorists found “no evidence of major
criminal behavior, such as murder, beyond the petty crime normally associated with terrorist
groups, such as money laundering (of tiny sums) and theft.” Merari (2010) reported similar
findings. Likewise, the New York Police Department reports that violent radicals are generally
free of a record of past crime (Silber & Bhatt, 2007). Bakker (2006, p. 43), on the other hand, in
a study of 242 jihadi terrorists in Europe, concluded that “at least a quarter of the sample” had a
The crime of most theoretical relevance to the risk assessment of future violent terrorism,
of course, is past violent terrorism. However, I know of no studies that directly address past
terrorism as a risk factor for future terrorism, perhaps because people adjudicated as terrorists are
Running head: INDIVIDUAL RISK ASSESSMENT OF TERRORISM 13
infrequently given the opportunity to recidivate. The limited data mentioned earlier on detainees
released from Guantanamo—whose post-release rate of actual or suspected terrorism is
estimated to be between six percent (Bergen et al, 2011) and 25 percent (Office of the Director of
National Intelligence, 2010)—may be relevant here. Not all of the people released from
Guantanamo were ever adjudicated as having committed an initial act of terrorism, however, so
it is unclear what fraction of this 6 to 25 percent are actually “recidivists.”
That terrorists who commit suicide bombings are otherwise suicidal is a plausible
hypothesis. However, a review of five published studies of prospective suicide terrorists or the
surviving friends and families of deceased terrorists concluded that “the many discrepancies
uncovered between suicide terrorists and other suicides on key factors known to underpin
suicidality, suggest that such terrorists are not truly suicidal and should not be viewed as a
subgroup of the general suicide population” (Townsend, 2007, p. 35). Similarly, Pape (2005, p.
172) noted that “many suicide terrorists are acting on the basis of motives fundamentally
different from those that underlie ordinary suicide and would probably not commit suicide absent
the special circumstances that create these motives.” Merari (2010, p. 221) in this regard
concluded that suicide terrorism “differs sufficiently from ordinary suicide to be recognized as
sui generis.” Only a small proportion of individuals involved in terrorism choose to be involved
in suicide terrorism (Crenshaw, 2007; LaFree & Dugan 2009; cf Lankford, 2010): the great
majority of terrorists only detonate bombs that they are not wearing.
While many terrorist organizations fund their operations by trafficking in drugs to be
used by others (Dishman, 2001), there is little evidence that terrorists themselves are prone to
substance abuse. Indeed, Merari (2010, p. 221), in his large study of Palestinian suicide terrorists,
found that “none whatsoever were alcohol or drug abusers (most of the suicides were members
of extremist Islamic organizations, which have conducted a fierce struggle against drugs in the
Palestinian society, and alcohol drinking is, of course, forbidden for Muslims)” (see also Atran,
Scholarship on personality disorder among terrorists has focused on the concept of
psychopathy. Borum (2011, p. 19), for example, has noted that “although terrorists often commit
heinous acts, they would rarely be considered classic ‘psychopaths.’” Merari (2010, p. 254)
concluded that “contrary to common criminals, suicide bombers are unlikely to display
psychopathic characteristics; psychopaths do not sacrifice themselves for the community” (see
also Victoroff, 2005). Likewise, McCauley (2007, p. 15) observed that “[t]he mutual
commitment and trust that is evident within [terrorist groups] and in the cooperation among the
groups is radically inconsistent with the psychopathic personality.”
The search for personality traits that distinguish terrorists from non-terrorists with any
degree of reliability has a long and frustrating history (Reich, 1990; Hoffman, 2006; Davis &
Running head: INDIVIDUAL RISK ASSESSMENT OF TERRORISM 14
Cragin, 2009; McCormick, 2003; Sageman, 2008). In recent years, and after a great many
failures, that search has been “more or less abandoned” (Smelser, 2007, p. 94; Weine, 2009). No
existing personality test or other psychological instrument has been reliably shown to produce
scores for any psychological trait that significantly differentiates—either predictively or
postdictively—people in a given population who engage in terrorist acts from people in the same
population who do not.
Importantly, however, Merari (2010, p. 253) reasonably has cautioned that the conclusion
that terrorists do not share personality characteristics “rests on the absence of research rather than
on direct findings.”
A scientifically sound conclusion that terrorists have no common personality traits must
be based on many comparative studies of terrorists from different countries and
functions, using standard psychological tests and clinical interviews. As such studies
have not been published, the only scientifically sound conclusion for now is that we do
not know whether terrorists share common traits, but we cannot be sure that such traits do
not exist” (p. 235).
From the existing research, therefore, it appears that none of the four overlapping
dimensions of the risk of common violence identified by Kroner et al (2005)—criminal history,
an irresponsible lifestyle, psychopathy and criminal attitudes, and substance abuse—characterize
those who commit violent terrorism. In addition, there is little empirical evidence supporting the
validity of other putative risk factors for terrorism beyond what is already obvious (i.e., age,
gender, and perhaps marital status). Indeed, the strongest empirical findings are entirely
negative: terrorists in general tend not to be impoverished or mentally ill or substance abusers or
psychopaths or otherwise criminal; suicidal terrorists tend not to be clinically suicidal. In no
society studied to date have personality traits been found to distinguish those who engage in
terrorism from those who refrain from it.
Part IV: Conceptual and Methodological Challenges
Merari and Friedland (1985, p. 348) surely understate the case when they write that “the
subject of terrorism does not lend itself easily to research” (see also Crenshaw, 1990; Taylor,
2010). Here, I lay out four conceptual and methodological issues that must be confronted and
resolved—at least provisionally—before a robust program of short- and long-term research to
improve the individual risk assessment of terrorism can be fully operational (Fein & Vossekuil,
1999). The four issues concern the heterogeneity of what is meant by “terrorism,” the optimal
degree of structuring a risk assessment procedure, the need for more robust risk factors, and the
development of an infrastructure for validating these risk factors.
In his own small-scale study of Palestinian terrorists, Merari (2010, p. 113), reported that “In general, as a group
the would-be suicides differed significantly in their personality characteristics from non-suicide terrorists. This
difference suggests that certain types of people are more likely to be attracted to suicide terrorists’ missions. Most
were socially marginal youngsters with a keen sense of social failure. Shy and withdrawn, they lacked self-
confidence and feared rejection, were eager to please, and tended to avoid conflicts.”
Running head: INDIVIDUAL RISK ASSESSMENT OF TERRORISM 15
First, however, it is necessary to mention one crucial issue that will not be addressed
further here: the verification of risk factors that rely in whole or in part on the statements of the
individuals whose risk of terrorism is being assessed. As the National Research Council (NRC)
Workshop Summary, Field Evaluation in the Intelligence and Counterintelligence Context
(2010, p. 7), correctly observed, a key question in any form of risk assessment for terrorism that
relies on subjects’ self-report is, “Are they being honest?”
The empirical literature on lie detection is vast and remarkably contentious (e.g., Bond &
DePaulo, 2008; Wagner, 2010; Loftus, 2011; Vrij, Granhag, Mann & Leal, 2011). A
comprehensive or even a highly selective review of this literature is beyond the scope of this
article. Methods of answering the “honesty” question were aired at length in the 2010 NRC
Workshop, as well as by Bhatt and Brandon (2008), Brandon, 2011) and Evans, Meissner,
Brandon, Russano, and Kleinman (2010). Rather than reiterate the many excellent points made in
these recent sources, I will refer the reader to them and otherwise bracket this issue for further
consideration as an agenda for research on the risk assessment of terrorism is developed.
Issue 1: The Heterogeneity of the Outcome: Terrorist Types, Processes, and Roles
Is terrorism a sufficiently unified phenomenon that it constitutes a coherent outcome
measure in risk assessment research? Or, as the National Science and Technology Council (2005,
p. 7) stated, is it the case that “‘terrorism’ may oversimplify different types of actors, warfare,
and motivations, encapsulating them in a single group or act so that critical variables are
overlooked”? The Global Terrorism Database lists the “top five” of the twenty most active
terrorist organizations in terms of attack frequency since 1970 as Peru’s Shining Path, the
Basque Fatherland and Freedom organization, El Salvador’s Farabundo Marti National
Liberation Front, the Irish Republican Army, and the Revolutionary Armed Forces of Columbia
(LaFree & Dugan, 2009, Table 1). The question is whether these groups—or more recently
active ones, such as al-Qaeda—have anything in common, other than their willingness to use
violence against noncombatants in order to advance their (very different) political goals.
Many risk assessment instruments for common violence “split” rather than “lump” the
outcome variable (Zerubavel, 1996); that is, rather than attempt to assess the risk of violence in
general, they attempt to assess the risk of specific types of violence, such as domestic violence
(Hilton, Harris, & Rice, 2009), sexual violence (Hart & Boer, 2010), violence among people with
mental illness (Monahan et al, 2001), violence among prisoners (Andrews, Bonta, & Wormith,
2004), violence in workplaces (White & Meloy, 2010), or violence in schools (Cornell, 2009).
As the NRC (2003) importantly noted with regard to the polygraph:
Polygraph screening may be useful for achieving such objectives as deterring security violations, increasing
the frequency of admissions of such violations, deterring employment applications from potentially poor
security risks, and increasing public confidence in national security organizations. On the basis of field
reports and indirect scientific evidence, we believe that polygraph testing is likely to have some utility for
such purposes. Such utility derives from beliefs about the procedure’s validity, which are distinct from
actual validity or accuracy… However, overconfidence in the polygraph—a belief in its accuracy that goes
beyond what is justified by the evidence—also presents a danger to national security objectives.
Overconfidence in polygraph screening can create a false sense of security among policy makers,
employees in sensitive positions, and the general public that may in turn lead to inappropriate relaxation of
other methods of ensuring security (p. 7).
Running head: INDIVIDUAL RISK ASSESSMENT OF TERRORISM 16
Analogous to this “splitting” rather than “lumping” trend in the risk assessment of
common violence, should research attempt to advance the risk assessment of terrorism in
general, or should it limit the outcome for a given risk assessment instrument to a specific type of
terrorism, on the hypothesis that different types of terrorism may function very differently from
one another, and therefore a risk factor for one type of terrorism may not be a risk factor for
another type (Forst, 2008)? Put more concretely, is it plausible to expect that the risk factors for
joining the Irish Republican Army are the same as the risk factors for joining the Taliban?
Candidates often mentioned as distinct “types” of terrorism include suicide terrorism (e.g., Pape,
2005), homegrown terrorism (e.g., Turchie & Puckett, 2007; Gartenstein-Ross & Grossman,
2009), “lone-wolf” assailants (Spaaij, 2010; Moskalenko & McCauley, 2011), domestic
terrorism (Sanchez-Cuenca & de la Calle, 2009), and “insider” threats (e.g., Bulling & Scalora,
2008; see in general Miller, 2006, Shaw, 2006).
In addition to these conceptually-derived types of terrorism, “types” can be empirically
generated. Rieger (2010), for example, used data from the 2007 Gallup World Poll, with a
sample size of 27,528 people in a total of 140 countries, to identify respondents who “strongly
believed the attacks of 9/11 were completely justified, [and] strongly believed that attacks
against civilians in pursuit of a goal were completely justified, especially those committed by
other civilians” (p. 77). To be classified as having “radical” views, a respondent must have given
the strongest possible response to these questions. Rieger contrasted such respondents with
others who did not share these views, and concluded that there were two types of potential
Type One Radicals were highly intolerant mainstream individuals who had little to no
confidence in their current government’s ability to meet what they saw as a desirable
future… Type Two Radicals were downscale individuals [in terms of income,] who
viewed themselves as victims and sought a strong leader and/or ideology for hope” (pp.
78-79; see also Rieger, 2011).
Finally, if one agrees with the Homeland Security Advisory Council’s Report on the
Future of Terrorism Task Force (2007) that “the most significant threat to the homeland today
stems from a global movement, underpinned by a jihadist/Salafist ideology” (p. 3), should
research on the risk assessment of terrorism simply take the jihadist/Salafist type of terrorism as
its initial research priority, recognizing full well that there are other types of terrorism whose
risk needs to be assessed, but perhaps with less urgency at this geopolitical moment?
Arguments can be made for and against any of the above choices of outcome measure,
much as arguments are made for “splitting” versus “lumping” in the risk assessment of common
violence. Narrower, well-specified types of terrorism may reflect more theoretically coherent
motivations on the part of the perpetrators, and may point to the existence of risk factors that are
specific to one rather than another type of terrorism.
Importantly, risk factors for lone-wolf terrorism may differ significantly from risk factors
for group-based terrorism. For example, as noted above, Crenshaw (1981), relying on studies of
the members of terrorist organizations, concluded that “the outstanding common characteristic of
terrorists is their normality.” The question cogently raised by Spaaij (2010, p. 862) is “whether
this observation applies not only to members of terrorist organizations, but also to lone wolf
Running head: INDIVIDUAL RISK ASSESSMENT OF TERRORISM 17
terrorists.” Both Spaaij (2010) and Hewitt (2003) suggest that Crenshaw’s observation may not
To the extent that certain variables function as valid risk factors for lone-wolf terrorism
but do not function as valid risk factors for group-based terrorism—or vice versa—then to lump
lone-wolf terrorists with group-based terrorists in a single analysis would serve to mask what
might otherwise be important findings.
On the other hand, a broader, more generic operational definition of terrorism would
allow for a larger sample size of terrorists, and thus more statistical power in analyzing risk
Whether one ultimately decides to use an operational definition of terrorism in general or
of a specific type of terrorism is one important question. A second important question is whether
to conceive of terrorism as an event that occurs or does not occur, or as a process that unfolds
over time and across organizational contexts (Horgan, 2005; Taylor and Horgan, 2006;
Suttmoeller, Chermak, Freilich, & Fitzgerald, 2011). Horgan (2008), for example, believes that
certain risk factors (described below) may provide a framework for “openness to socialization”
into terrorism, i.e., they may be relevant to assessing the risk of becoming initially involved in
terrorism. Once the individual moves further in the process of becoming a terrorist, however,
different risk factors may come into play.
Horgan’s distinction between initiation into terrorism and later continued involvement in
terrorist acts is reminiscent of Blumstein, Cohen, Roth, and Visher’s (1986) concept of “criminal
careers.” Risk factors for beginning to participate in a life of crime (i.e., for committing a first
crime) may be very different from risk factors for continuing to commit crimes at a high rate or
for a long period. “Thus, separating the participation rate from the course of active offenders’
criminal careers enables one to isolate influences on the initiation of offending from influences
on the frequency or duration of a criminal career” (Blumstein et al, 1986, p. 2).
Finally, in addition to differences between types of terrorism and phases in the process of
terrorism, there are different roles that can be played in a terrorist operation (Merari, 2010, p.
264; Gill & Young, 2011). As Horgan (2008, p. 86) notes:
The reality of terrorist movements today… is that this most public of roles and functions
tends to merely represent the tip of an iceberg of activity. Supporting the execution of a
violent attack are those directly aiding and abetting the event, those who house the
terrorist or provide other kinds of support, raise funds, generate publicity, provide
intelligence, and so forth. The person we think of as “the terrorist” is therefore fulfilling
only one of multiple functions in the movement, albeit the most dramatic in terms of
As a second example of the benefits of “splitting” rather than “lumping” in the choice of terrorism outcome
measure, Gartenstein-Ross & Grossman (2009, p. 14) in their study of 117 “homegrown” terrorists of the jihadi type
in the U.S. and the U.K., found that the homegrown terrorists they studied were “of a less privileged socioeconomic
upbringing, and had both a weaker educational background and weaker professional prospects than previous studies
suggest is typical of the global terrorist movement as a whole.”
Running head: INDIVIDUAL RISK ASSESSMENT OF TERRORISM 18
The choice of a broad or a narrow outcome measure in terrorism risk assessment research
is a crucial but often neglected issue. Yet, without clarity from the outset on whether we are
attempting to assess the risk of terrorism in the aggregate, or of specific types of terrorism—or of
specific phases in the process of becoming or of remaining a terrorist, or of specific roles in
terrorist activity—we are unlikely to produce a coherent body of empirical findings on the risk
assessment of terrorism.
Issue 2: The Optimal Degree of Structuring the Risk Assessment of Terrorism
In Part II, drawing heavily upon Skeem and Monahan (2011), I argued that the process
for assessing the risk of “common” violence might usefully be seen as having four components:
(a) identifying valid risk factors, (b) determining a method for measuring (“scoring”) each of
these risk factors (c) establishing a procedure for combining the scores on the various risk
factors, and (d) producing a final estimate of violence risk. I also argued that it is possible to
array five current approaches to the risk assessment of common violence according to whether
the approach structures none, one, two, three, or all four components of the risk assessment
process. Unfortunately, the range of approaches that can be taken in the risk assessment of
terrorism is likely to be significantly narrower than is the case with the risk assessment of
First, the option of structuring no components of the risk assessment process—i.e.,
relying on unmodified clinical prediction—is even less viable in the context of terrorism than it
is in the context of common violence. At least common violence is common: it occurs often, and
therefore a practicing clinician, especially a forensic psychologist or psychiatrist, may be able to
draw upon a large store of experience with violence in making his or her subjective judgments.
Some of that experience may include feedback on the accuracy (or lack thereof) of prior risk
assessments and the clinician may have learned valuable, if painful, lessons from that feedback
(Kahneman & Klein, 2009).
For two reasons, this clinical learning is unlikely to occur in the case of terrorism. First,
terrorism is much less common than “common” violence. This, of course, is a very good thing.
But it means that few clinicians, other than those who work in national security, are likely to
have a large—or even a small—store of experience with terrorism to draw upon in making their
clinical judgments. Second, whatever experience clinicians, including clinicians who work in
national security, have with assessing terrorism risk is unlikely to have been accompanied by the
kind of feedback from which the clinicians may have learned about their successes and mistakes:
no one who is clinically assessed as presenting a “high” risk of terrorism is about to be released
from detention or offered a military promotion or a job as a DoD contract employee. I address
this issue at greater length below.
Second, the two most structured options described earlier—modified and unmodified
actuarial risk assessment—seem patently infeasible in the context of assessing terrorism risk.
The sample size of people who actually engage in terrorist acts will never be large enough to
allow the statistical power needed to determine the optimal quantitative combination of risk
factor scores, or to generate a final estimate of risk that does not rely in substantial part on
clinical judgment. This issue is also addressed at greater length below.
Running head: INDIVIDUAL RISK ASSESSMENT OF TERRORISM 19
Of the five approaches to structuring the risk assessment of common violence identified
by Skeem and Monahan (2011), only two might feasibly apply to the risk assessment of
terrorism: modified clinical risk assessment, in which key risk factors for terrorism are identified,
and structured professional judgment, in which key risk factors for violence are both identified
and measured. Of these two feasible approaches, the latter seems clearly preferable, since the
former functions largely as a checklist to jog the assessor’s memory.
To my knowledge, only one instrument has been developed specifically to assess the risk
of terrorism, and that instrument adopts the structured professional judgment approach pioneered
by Webster et al (1997). The Violent Extremism Risk Assessment, or VERA, was developed in
Canada by D. Elaine Pressman (2009). Pressman concluded that three-quarters of the risk factors
for common violence on the HCR-20 had little or no relationship to risk factors believed to
characterize violent extremists. Therefore, she attempted to identify risk factors more relevant to
the context of terrorism:
Items on the VERA have been supported by the results of research undertaken in the area
of radicalization and terrorism, are based on previous work undertaken in collaboration
with RCMP [i.e., Royal Canadian Mounted Police] personnel having operational
experience with criminal violent extremists, have followed from discussions with
professionals in the security and intelligence fields and have used relevant information
obtained from interviews and self-report questionnaire data on radicalization (p. 21).
Each of the items scored on the VERA is scored as high, moderate, or low, based on
interviews and/or records. As with other structured professional instruments in clinical use, such
as the HCR-20, the items are not combined in clinical practice in a specified manner (e.g., by
summing scores), and the final risk estimate is a matter of informed clinical judgment.
The current version of the VERA (Consultative Version 2, Pressman & Flockton, 2010, p.
5), consists of 31 items grouped into five categories:
1. Beliefs and Attitudes, e.g., “Victim of injustice and grievances.”
2. Context and Intent, e.g., “Anger and expressed intent to act violently.”
3. History and Capability, e.g., “Network (family, friends) involved in violent action.”
4. Commitment and Motivation, e.g., “Driven by moral imperative, moral superiority.”
5. Protective Factors, e.g., “Family support for non-violence.”
Issue 3: The Need for New Risk Factors for Terrorism
As indicated in Part III above, existing research has largely failed to find valid nontrivial
risk factors for terrorism. Without the identification of valid risk factors, the individual risk
assessment of terrorism is impossible. Fortunately, several scholars have recently proposed
variables that they believe are promising candidates for being risk factors for terrorism. Horgan
(2008, p. 84), for example, while carefully noting that “the dangers of overgeneralization should
Running head: INDIVIDUAL RISK ASSESSMENT OF TERRORISM 20
be obvious,” hypothesizes that among the “predisposing risk factors for involvement in
terrorism” may be the following:
“1. The presence of some emotional vulnerability, in terms of feelings of anger,
alienation (often synonymous with feelings of being culturally uprooted or displaced and
a longing for a sense of community), and disenfranchisement…
2. Dissatisfaction with their current activity, whether it be political or social protest, and
the perception that conventional political activity just does not work or produce results...
3. Identification with victims—either real, in terms of personal victimization (e.g., by the
military or police) or less tangible...
4. Crucially, the person has to believe that engaging in violence against the state or its
symbols is not inherently immoral…
5. Also important is a sense of reward that the recruit has about what ‘being in this
movement’ represents. All suicide bombers, across the world, have one thing in common.
They come to believe that they will achieve more in death than they ever could in life…
6. Finally, kinship or other social ties to those experiencing similar issues, or already
involved, are crucial” (pp. 84-85).
In addition, McCauley and Moskalenko (2011), while strongly emphasizing that “there is
no one path, no royal road, no ‘conveyor belt’ from activism to terrorism” (p. 218), proposed six
individual-level “mechanisms of political radicalization” (p. 12).
1. Personal Grievance: “Harm to self or loved ones can move individuals to hostility and
violence toward perpetrators” (p. 13).
2. Group Grievance: “Threat or harm to a group or cause the individual cares about can
move the individual to hostility and violence toward perpetrators” (p. 21).
3. Slippery Slope: “Small involvements in political conflict can create new forces moving
an individual toward radicalization” (p. 35).
4. Love: “Love for someone already radicalized can move an individual toward
radicalization” (p. 49).
5. Risk and Status: “The attractions of risk-taking and status can move individuals,
especially young males, to radical political action” (p. 58).
6. Unfreezing: “Loss of social connection can open an individual to new ideas and new
identity that may include political radicalization” (p. 75).
Note that a number of Pressman and Flockton’s (2010), and Horgan’s (2008), and
McCauley and Moskalenko’s (2011) proposed risk factors overlap. Take two examples. First,
compare Pressman and Flockton’s “Victim of injustice and grievances,” with Horgan’s
Running head: INDIVIDUAL RISK ASSESSMENT OF TERRORISM 21
“Identification with victims—either real, in terms of personal victimization (e.g., by the military
or police) or less tangible,” and with McCauley and Moskalenko’s “Harm to self or loved ones
can move individuals to hostility and violence toward perpetrators.” Second, compare Pressman
and Flockton’s “Network (family, friends) involved in violent action,” with Horgan’s “Kinship
or other social ties to those experiencing similar issues, or already involved, are crucial,” and
with McCauley and Moskalenko’s “Love for someone already radicalized can move an
individual toward radicalization.”
From my own reading of the empirical literature on terrorism, I would single out four
categories of variables—each of which can find a parallel in Pressman and Flockton (2010),
Horgan (2008), and/or McCauley and Moskalenko (2011)—that seem to be auspicious
candidates for terrorism risk factors. These categories center on ideologies, affiliations,
grievances, and moral emotions.
A study analyzing suicide terrorists’ farewell videos and interviewing mothers of
deceased suicide bombers found that the stated reasons for suicide terrorism were almost
uniformly ideological (Kruglanski, Chen, Dechesne, Fishman, & Orehek, 2009). In this regard,
Saucier, Akers, Shen-Miller, Knežević, & Stankov (2009, p. 256) define an ideology they term
militant extremism as “zealous adherence to a set of beliefs and values, with a combination of
two key features: advocacy of measures beyond the norm (i.e., extremism) and intention and
willingness to resort to violence (i.e., militancy)” (see also Stankov, Higgins, Saucier, &
Knežević, 2010; Stankov, Saucier, & Knežević, 2010; and Gartenstein-Ross & Grossman,
To develop a model of militant-extremist ideology in a “culture-fair” manner, Saucier et
al (2009) extracted statements from written material produced by extremist groups from seven
regions around the world: Europe, Middle East, Sub-Saharan Africa, South Asia, East Asia,
Latin America, and North America (see also Smith, 2004). To be sampled, the groups had to be
active within the last 150 years and had to have committed actual violence involving the death of
multiple persons outside the group. Saucier et al (2009) identified 16 themes that recurred in
multiple written statements. The 16 themes are summarized in Table 1.
The authors hypothesize that the themes “could be assembled to form a coherent and
potentially compelling narrative, and this narrative may be the source of much of the appeal that
salient militant-extremist groups generate” (p. 269; see also Leuprecht, Hataley, Moskalenko, &
McCauley, 2009, 2010). The narrative that they propose is as follows:
We (i.e., our group, however defined) have a glorious past, but modernity has been
disastrous, bringing on a great catastrophe in which we are tragically obstructed from
reaching our rightful place, obstructed by an illegitimate civil government and/or by an
enemy so evil that it does not even deserve to be called human. This intolerable situation
calls for vengeance. Extreme measures are required; indeed, any means will be justified
for realizing our sacred end. We must think in military terms to annihilate this evil and
purify the world of it. It is a duty to kill the perpetrators of evil, and we cannot be blamed
for carrying out this violence. Those who sacrifice themselves in our cause will attain
Running head: INDIVIDUAL RISK ASSESSMENT OF TERRORISM 22
glory, and supernatural powers should come to our aid in this struggle. In the end, we will
bring our people to a new world that is a paradise (p. 265).
It is crucial to stress here the vast gulf between terrorist ideology and terrorist action
(Karagiannis & McCauley, 2006; Horgan, 2008; Kurzman, 2011). As McCauley and
Moskalenko (2011) note, “Polls in Muslim countries indicate that millions sympathize with
jihadist goals or justify terrorist attacks. But Muslim terrorists number only in the thousands. The
challenge is to explain how only one in a thousand with radical beliefs is involved in radical
action” (p. 5; see also Merari, 2010, p. 246).
If certain ideological commitments disproportionately serve a facilitating role in the
initiation to—or in the continuation of—terrorism, the existence of such commitments might
function as an individual risk factor for terrorism, or at least for some types of terrorism.
is so, the reliable measurement of these ideological commitments is an important methodological
pursuit (Borum, in press a, in press b).
In addition, given that many more people espouse ideological commitments conducive to
terrorism than participate in terrorist acts, perhaps these ideological commitments manifest
themselves in terrorist behavior primarily in individuals with certain pre-existing personality
characteristics (although, as discussed above, no such characteristics have yet been identified
(Merari, 2010)). One candidate for a personality characteristic that might differentiate— among
people with what Saucier et al (2009) call militant-extremist ideological commitments—those
who refrain from terrorism and those who engage in terrorism is “boldness” (Patrick, Fowles, &
Krueger, 2009; Patrick, 2010) or “fearlessness” (Newman, Curtin, Bertsch, & Baskin-Sommers,
People who commit terrorist acts tend to associate with other people who commit
terrorist acts (Smith, 2008; Weine, Horgan, Robertson, Loue, Mohamed, & Noor, 2009).
Sageman (2008) reported that about 70 percent of the people who join al-Qaeda do so with
friends, and about 20 percent do so with kin. Atran (2008) noted that friends tend to become kin
as they marry one another's sisters and cousins. The web can greatly facilitate this terrorist
bonding process (Theohary & Rollins, 2011).
Along these lines, Ginges, Hansen, and Norenzayan (2009) propose an alternative to the
hypothesis that certain religious beliefs (e.g., the belief that “martyrs” will be rewarded in an
afterlife) directly influence support for suicide terrorist attacks. They refer to their alternative as
the coalitional-commitment hypothesis: the relationship of religion to suicide attacks may be
independent of any particular religious beliefs and more a function of religion’s powerful ability
to strengthen coalitional identities and to foster “parochial altruism.” Parochial altruism is a
For example, Moskalenko & McCauley (2011, p. 124) have recently noted that “Ideology and ideas of justice
may… be more important for solo political action than for action embedded in radical groups or terrorist
I am grateful to Jennifer Skeem for this suggestion.
Running head: INDIVIDUAL RISK ASSESSMENT OF TERRORISM 23
concept developed by Choi and Bowles (2007) that combines parochialism, i.e., hostility toward
individuals who are not members of one’s own group, with altruism, i.e., benefitting in-group
members at a tremendous cost to oneself.
Ginges et al (2009) report several studies finding that
the frequency with which Palestinian Muslims attend mosque, but not their frequency of prayer,
positively predicted support for suicide attacks. In addition, experimentally bringing to mind
synagogue attendance, but not experimentally bringing to mind prayer, increased the likelihood
that Israeli settlers would state that a suicide attack against Palestinians was “extremely heroic.”
In another study, with a multireligious sample, the frequency of attendance at organized religious
services, but not the frequency of prayer, predicted parochial altruism (see Putnam & Campbell,
2010). Ginges et al conclude that the relationship between religion and support for suicide
attacks is independent of “devotion to particular religious belief, or indeed to religious belief in
general. [Rather, the relationship] is a function of collective religious activities that facilitate
popular support for suicide attacks and parochial altruism more generally” (p. 230; see also
Liddle, Machluf, & Shackelford, 2010; Ginges, Hansen, & Norenzayan, 2010; Graham & Haidt,
2010; Liddle, Bush, & Shackelford, 2011). The well-known group-polarization effect, whereby
group discussion tends to make those participating in it advocate more extreme positions and
riskier actions than those not participating in it (McCauley & Moskalenko, 2010) may play an
important role in explaining why coalitional-commitment mediates the relationship between
religious belief and terrorism.
If kinship, friendship, and romantic affiliation often play a crucial role in the
development of terrorist ideology and in the transformation of that ideology into terrorist actions,
risk assessment must focus not just on the individual being assessed, but must also incorporate
information on the behavior of those with whom the individual closely affiliates. The extensive
literature on criminal gangs may be a source of useful insights in this regard (Sandia National
Laboratories, 2002; Goldson, 2011).
Personal and group grievances are frequently implicated in accounts of the development
of terrorism (Atran, 2003). McCauley and Moskalenko (2011), for example, note that personal
grievances (i.e., “[h]arm to self or loved ones”) can combine with group grievances (i.e.,
“[t]hreat or harm to a group or cause the individual cares about”) in two primary ways:
One possibility is that each mechanism adds its independent contribution to
radicalization. The second possibility is that the power of multiple mechanisms is more
like a multiplication than an addition. There could be synergisms such that particular
combinations of mechanisms are particularly potent… Our cases of individual
radicalization by personal grievance showed considerable overlap in experience with
cases of individual radicalization by group grievance. We were led to recognize that
these two kinds of grievance are often found together. Indeed either kind of grievance is
likely to produce the other. Personal grievance can lead an individual to seek out and
On the concept of altruism, McCauley and Moskalenko (2011) note that “studies of altruism have shown the
importance of sympathy and empathy in predicting help for a stranger in distress. Although altruism research has not
yet examined the relation between empathy and aggression toward the perpetrator of a stranger’s distress, the
importance of individual differences in empathy for understanding political radicalization may be worth pursuing”
Running head: INDIVIDUAL RISK ASSESSMENT OF TERRORISM 24
cooperate with others feeling anger toward the same perpetrator: the personal then
becomes political. Group grievance can lead to involvement in conflicts with the
government and police that are experienced as unjustified repression: the political then
becomes personal (pp. 214-215.
Others have argued that one particular grievance—the loss of a loved one—may
indirectly remind a person of his or her own mortality in a particularly personal way, and that
being reminded of one’s own death has important behavioral consequences. Terror Management
Theory, for example, holds that people respond to what that theory refers to as the “existential”
fear of death by clinging to their existing worldviews more tenaciously, since those worldviews
may provide a measure of protection against otherwise debilitating anxiety. As stated by
Pyszczynski, Rothschild, and Abdollahi (2008, p. 319), “in the face of elevated concerns about
death, people are more prone to dehumanizing, vilifying, and supporting the killing of
worldview-threatening others.” A recent meta-analysis concluded that the central hypothesis of
the theory—that death affects us without our conscious realization—“is robust and produces
moderate to large effects across a wide variety of mortality salience manipulations as well as
attitudinal, behavioral, and cognitive dependent variables”
(Burke, Martens, & Faucher, 2010,
Several studies have directly applied Terror Management Theory to the study of terrorism
(for a review, see Vail, Motyl, Abdollahi, & Pyszczynski, 2010). Pyszczynski, Abdollahi,
Solomon, Greenberg, Cohen, and Weise (2006), for example, in a randomized experimental
study of Iranian college students, found that students reminded of death were more supportive of
“martyrdom” attacks against the United States than students not reminded of death. In addition,
Kokdemir and Yeniceri (2010) found that predominantly Muslim university students in Turkey,
when reminded of death, wanted their country to have stronger relations with Turkmenistan (also
predominantly Muslim) and weaker relations with England and Greece. Finally, Chatard, Arndt,
and Pyszczynski (2010) have found that the death of loved ones leads to a long-term polarization
of political attitudes and opinions.
Grievances, particularly in the form of the loss of loved ones due to military actions by
those perceived to be enemies, may be an undervalued individual risk factor for terrorism.
Grievances may be particularly potent risk factors for terrorism in “cultures of honor” (Nibbett
&Cohen, 1996) in which “men are sensitive to a cultural script in which aggression is used to
restore threatened manhood” (Bossin & Vandello, 2011, p. 83).
The three risk factors for terrorism just discussed—ideology, affiliations, and
grievances—have been combined by Kruglanski, Chen, Dechesne, Fishman, & Orehek (2009)
into an overarching notion of a “significance quest” that is undertaken by suicidal terrorists:
This is not to say that there is general agreement that “existential” fear of death is what produces these effects. See
Navarrete and Fessler (2005):
Adherence to ingroup ideology increases after exposure to death-related stimuli, a reaction that proponents
of terror management theory explain as a psychological defense against the uniquely human existential fear
of death. We argue that existential concerns are not the relevant issue; rather, such concepts can be
subsumed under a larger category of adaptive challenges that prime coalitional thinking (p. 297).
Running head: INDIVIDUAL RISK ASSESSMENT OF TERRORISM 25
Recent analysis of the motivations for suicidal terrorism have identified a broad variety
of motives (the “fatal cocktail”) having to do with potential perpetrators’ (1) personal
traumas and frustrations, (2) ideological reasons, and (3) social pressures to which they
may be subjected. [W]e introduced the notion of significance quest as an integrative
concept tying these motivational categories together: Personal traumas and frustrations
could encourage a “collectivistic switch” to a terrorism-justifying ideology because the
latter may afford a means for restoring the lost significance occasioned by various
unsettling events. Besides, terrorism-justifying ideologies may afford a relatively simple
means of substantial significance gain and attainment of a hero or a martyr status in the
eyes of one’s community (p. 353).
The final set of variables that may have particular promise as risk factors for terrorism
concern emotions that are increasingly being termed “moral.”
Numerous scholars recently have argued that terrorism can only be understood in terms
of morality, that is, in terms of other groups violating one’s own group’s “sacred values”
(Ginges, Atran, Sachdeva, & Medin, 2011). Tetlock (2002) defines a sacred value as “any value
toward which a moral community proclaims, at least in rhetoric, an unbounded or infinite
commitment.” For example, Ginges, Atran, Medlin, and Shikaki (2007) report several
experiments carried out with Palestinian and Israeli participants showing that violent opposition
to compromise over values considered by one group or the other to be sacred—e.g., exchanging
land for peace, sovereignty over Jerusalem, and the right of Palestinian refugees to return to their
former lands inside Israel—is increased by offering material incentives (i.e., the payment of
money) to compromise with one’s adversary, but is decreased when the adversary makes
symbolic compromises over their own sacred values (e.g., recognizing the right of the other to
exist as a state). In other words, the use of material incentives to promote the resolution of
conflict backfires when adversaries see these incentives as a challenge to the “sacredness” of
their moral values (see also Atran, Axelrod, & Davis, 2007).
Ginges and Atran (2009a) have
replicated this result with Indonesian madrassa students, with the “backfire effect” being the
strongest among the most radicalized students. As summarized by Ginges and Atran (2009b), it
appears that “choices people make in violent intergroup conflicts, from whether to accept a
compromise to whether individuals commit themselves to violent collective action, are bound by
moral commitments to collective interests” (p. 122. See also Ginges & Atran, 2011).
In this regard, Haidt (2012; Haidt & Kesebir, 2010; see also Hutcherson & Gross, 2011)
has described a “new synthesis” in the study of morality that may have important implications
for studying the violent actions in which terrorists feel morally obligated to engage. A key aspect
of this new synthesis is the primacy of moral emotions over moral reasoning. “Moral reasoning,
when it occurs, is usually a post-hoc process in which we search for evidence to support our
initial intuitive reaction” (Haidt, 2007, p. 998). Haidt (2003) posited that the principal moral
emotions used to condemn others are anger, contempt, and disgust. McCauley and Moskalenko
(2011, pp. 19-20) have focused on the relationship between anger and terrorism:
In a related article, Rai and Fiske (2011) have stated, “When someone offers you a million dollars for your
daughter, you do not counter with three million—you regard the offer as heinously offensive” (p. 66).
Running head: INDIVIDUAL RISK ASSESSMENT OF TERRORISM 26
There seems to be an easy path from personal grievance to anger to aggression toward the
perpetrator…But [there are] two complications about this path. The first complication is
the transition from revenge against a particular perpetrator to justice against a particular
class or category of people… The complication of the path between personal grievance
and political violence is then the psychology of attribution in which both victims and
perpetrators are raised to the level of classes or categories. We need a theory that can
describe when and how individual events are interpreted in terms of conflict between
groups… The second complication of the path from personal grievance to political
violence is that the experience of anger is relatively brief. Psychologists studying
emotion, whether anger or any other emotion, try to measure the emotion or its effects
only in the minutes immediately after instigating the emotion. How can an emotional
experience that lasts only minutes explain political violence that is planned and carried
out over periods of months and years?
Matsumoto (2010), on the other hand, sees disgust as the moral emotion most closely
associated with terrorism (Rozin, Haidt, & McCauley, 2008; Hodson & Costello, 2007). Note
that ways to measure moral emotions outside the context of terrorism already exist. Some of
these procedures rely on self-report (e.g., the Novaco Anger Scale (Novaco, 2004); the Disgust
Scale-Revised (Haidt, McCauley & Rozin, 1994, modified by Olatunji et al (2007)), making
them subject to concerns regarding subjects’ feigning answers. Other measurement procedures,
however, rely on physiological measures of disgust (Sherman, Haidt & Coan, 2010), or on the
recognition of micro-expressions (Ekman, 2007), which may be more difficult to manipulate
(e.g., see Matsumodo (2005) on ratings of expressions of contempt).
I have argued here that four categories of variables have promise as risk factors for
terrorism: the ideologies, affiliations, and grievances of potential terrorists, and the emotions that
they experience as morally salient. It is entirely possible that some pathways to some types of
terrorism operate through one set of risk factors and other pathways to other types of terrorism
operate through a different set of risk factors.
Issue 4: The Problem of Validation
To appreciate the profound problem of empirically validating an instrument for assessing
an individual’s risk of terrorism, it may be useful to contrast the hypothetical validation of such
an instrument with the actual validation of an existing instrument for assessing the risk of
common violence. I take as an illustration the Classification of Violence Risk (COVR) (Monahan
et al, 2001)
, since that is the instrument mentioned in the DoD report, Protecting the Force
In brief, to validate the COVR, the instrument was administered to two independent
samples of acute mental hospital inpatients (n = 700). A stratified random sample of 177 of these
patients—each of whom had been classified by the instrument as either at “high” risk or at “low”
risk of violence—were prospectively followed in the community for four months after discharge
from the hospital (Monahan, Steadman, Robbins, Appelbaum, Banks, Grisso, Heilbrun, Mulvey,
Roth, & Silver, 2005). Of the 700 patients whose risk of violence was assessed, only three
Full disclosure: I am one of the co-owners of the Classification of Violence Risk.
Running head: INDIVIDUAL RISK ASSESSMENT OF TERRORISM 27
(0.4%) had not been discharged from the hospital within ten weeks after admission, and these
three patients were eliminated from the analysis. Follow-up data—consisting of interviews with
the patients and with collaterals (e.g., family members) about the patients’ violence in the
community during the first four months after hospital discharge (with the confidentiality of the
interviews guaranteed by a Federal Confidentiality Certificate), as well as police and hospital
records—were obtained for 157 of the 177 patients in the sample (89%).
The results of the COVR validation study were that during the follow-up approximately
(1) one-in-ten of the patients classified by the instrument as “low” risk of violence committed a
violent act; and (2) one-in-two of the patients classified by the instrument as “high” risk of
violence committed a violent act. This difference was highly statistically significant.
Contrast this actual validation study of an instrument to assess the risk of common
violence with a hypothetical validation study of an instrument to assess the risk of terrorism. For
example, consider the validation of a terrorism risk assessment instrument to be used in deciding
whether to release from detention an individual found to have committed such an act—what was
earlier called terrorism as crime. Three questions immediately come to mind:
Where does one find 700 people who have committed an act of terrorism to whom
the terrorism risk assessment instrument could be administered?
When does it happen that virtually all (99.6%) of the people adjudicated as
terrorists are released into the community in a short period of time?
How does one locate, interview, and obtain official data concerning the great
majority (89%) of those terrorists who have been released into the community, in
order to determine whether or not they have, in fact, committed a new act of
As stated by the National Research Council (2010, p. 33), “One reason that the area of
counterterrorism… has so few evaluation studies is the fact that terrorist activities, unlike
criminal activities, are rare. Thus researchers have relatively little information to work with.” A
second reason is that the cost of a false negative prediction—concluding that an individual will
be safe when in fact he or she goes on to commit a violent act—while often high in the case of
common violence, may be catastrophically higher in the case of violent terrorism. No one wants
to be the risk assessor who recommended the release of a detainee—or the promotion of a
military officer, or the hiring of a civilian contractor—who later flies a plane into a building (see
Tetlock & Mellers (2011) on “accountability ping-pong,” and McGraw, Todorov, & Kunreuther
(2011) on “preventing terrorism or preventing blame”).
For the reasons given above, it is difficult to avoid the conclusion that in no real-world
national security context can an instrument to assess the risk of terrorism be prospectively
validated in the same manner that risk assessment instruments for common violence are
prospectively validated. That is, in no real-world national security context can an instrument to
assess the individual risk of terrorism be prospectively validated by
Running head: INDIVIDUAL RISK ASSESSMENT OF TERRORISM 28
administering the risk assessment instrument to large groups of people in either a
terrorism as crime or a terrorism as workplace violence context, and
releasing a large portion of these individuals from detention—including those
who score as “high” risk of terrorism on the instrument—or employing them as
members of the U.S. military or as DoD civilian contractors, and
monitoring their behavior to determine which ones commit terrorist acts and
which ones do not, in order to determine whether the instrument is able to
statistically distinguish the former from the latter.
This, as the saying goes, is not going to happen.
If prospective validation is not remotely feasible, “known group” validation methods
(Cronbach & Meehl, 1955; DeVellis, 2011) may be the most that can realistically be achieved
when validating risk factors for terrorism—singly, or aggregated into a risk assessment
instrument. In a known-group validation, the researcher would (a) measure the presence of a
putative risk factor among a group of people known to be terrorists, and (b) measure the presence
of the same putative risk factor among a matched group of people from the same population who
are known not to be terrorists, and (c) compare the prevalence of the putative risk factor between
the two groups. If the prevalence rates of the putative risk factor do not differ to a statistically
significant degree, the researcher can conclude that the putative risk factor is in fact not a valid
risk factor for terrorism. If the prevalence rates of the two groups are statistically significantly
different from one another, the researcher can conclude that the putative risk factor fulfills at
least one of the two criteria for being a valid risk factor set forth by Kraemer et al (1997): it
correlates with the outcome. Whether the putative risk factor fulfills the other Kraemer et al
criterion for being a valid risk factor—did it precede the outcome in time?—would still need to
be established. For example, if a certain ideological commitment, or a given moral emotion,
became manifest in terrorists only after they had already become terrorists, that commitment or
emotion would not be a risk factor for initiation into terrorism.
There may be few viable alternatives to relying on known-group methods to validate risk
factors for terrorism. If this is the case, an infrastructure for facilitating researchers’ access to
known groups of terrorists
and non-terrorists from the same populations may be crucial for
conducting a program of research on the individual risk assessment of terrorism (see Horgan,
2011). This research should be stringently governed by applicable legal and ethical standards
(Kennedy & Williams, 2011).
This article attempted to identify the most important conceptual and methodological
challenges that must be overcome if the risk assessment of terrorism is to make the same
As examples of “known groups” of detained terrorists, the Federal Bureau of Prisons (2010) houses “216
individuals with a history of or nexus to international terrorism.” In addition, 172 people are detained as enemy
combatants at the U.S. Naval Base in Guantanamo Bay, Cuba (Savage et al, 2011), and approximately 1,800 people
are detained in the Parwan Detention Facility in Bagram, Afghanistan (Hennessy-Fiske, 2011).
Running head: INDIVIDUAL RISK ASSESSMENT OF TERRORISM 29
progress that in recent years has distinguished the risk assessment of other forms of violence.
Four principal conclusions are offered.
First, clarity from the outset on what risk we are trying to assess—the risk of terrorism in
the aggregate, or of specific types of terrorism, or of specific phases in the process of becoming a
terrorist, or of specific roles in terrorist activity—is a prerequisite to progress in research.
Second, one current approach to the risk assessment of common violence—structured
professional judgment—usefully may be applied to the risk assessment of terrorism. However,
given that many known risk factors for common violence are not risk factors for terrorism, the
substantive content of any instrument to assess the risk of terrorism will be very different from
the substantive content of existing instruments that address common violence.
Third, since there is little evidence supporting the non-trivial validity of any individual
risk factors for terrorism, the highest priority for research should be the identification of robust
individual risk factors. Promising candidates include ideologies, affiliations, grievances, and
Finally, it is highly unlikely that an instrument to assess the risk of terrorism can be
validated prospectively. An infrastructure for facilitating access to known groups of terrorists
and non-terrorists from the same populations may be crucial for conducting a scientifically
rigorous and operationally relevant program of research on the individual risk assessment of
Running head: INDIVIDUAL RISK ASSESSMENT OF TERRORISM 30
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Running head: INDIVIDUAL RISK ASSESSMENT OF TERRORISM 46
Sixteen Themes Detected in Statements from Militant-Extremist Groups (from Saucier et al,
1. One’s own group as tragically obstructed
2. Glorification of the past (especially of one’s group)
3. Utopian thinking
4. Catastrophizing: a focus on calamities in past, present, future
5. Perceived need for unconventional and extreme measures
6. Rationalizations absolving oneself (and one’s group) of responsibility for any harmful
consequences of one’s violence
7. Atypical overextension of military terminology (to all areas of life)
8. Expectation of supernatural intervention
9. Imperative to annihilate evil and purify the world
10. Duty to kill or initiate hostilities
11. Glorification of dying for the cause
12. Machiavellianism in service of the sacred
13. Elevation of intolerance and vengeance to a virtue
14. Dehumanizing one’s adversaries
15. Modernity seen as disastrous
16. Civil government seen as illegitimate