University of Virginia School of Law Public Law and Legal Theory Working Paper Series 2011- 34

The Individual Risk Assessment of Terrorism

John Monahan

University of Virginia School of Law

September 2011

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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

John Monahan

University of Virginia

Author Note

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:

jmonahan@virginia.edu

© (2012) American Psychological Association

Running head: INDIVIDUAL RISK ASSESSMENT OF TERRORISM 2

Abstract

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’s1 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.”

1 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 adjudication2 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

assessments.

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

2 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.”3

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).4 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”

(p. 12).

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

3 The Executive Order is available at http://www.whitehouse.gov/the-press-office/2011/03/07/executive-order-

periodic-review-individuals-detained-guant-namo-bay-nava

4 “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).5

5 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,

2006).

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 factor6

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.7

and transportation contracts is the insurgent’s second-largest funding source” (with the drug trade being the largest

funding source).

6 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.”

http://www.oed.com/view/Entry/152090?redirectedFrom=profiling#eid

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).

7 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

factors.

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

problems.

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

endeavors:

“(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

common crime:

“(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.

Age

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.

Gender

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).

Marital Status

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

Social Class

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.

Prior Crime

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

criminal record.

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.”

Suicidality

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.

Substance Abuse

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,

2002).

Personality Disorder

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.”

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).8

Summary

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.

8 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.9

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).

9 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

terrorists:

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

apply.10

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

assessment data.

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

direct consequences.

10

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

common violence.

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.

Ideology

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,

2009).

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.11

If this

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,

2009).12

Affiliations

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

11

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

organizations.”

12

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.13

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).

Grievances

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

13

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”

(p. 33).

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”14

(Burke, Martens, & Faucher, 2010,

p. 187).

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:

14

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.”

Moral Emotions

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).15

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:

15

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)16

, since that is the instrument mentioned in the DoD report, Protecting the Force

(2010b).

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

16

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

terrorism?

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 terrorists17

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).

Conclusions

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

17

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

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 scientifically

rigorous and operationally relevant program of research on the individual risk assessment of

terrorism.

Running head: INDIVIDUAL RISK ASSESSMENT OF TERRORISM 30

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Table 1

Sixteen Themes Detected in Statements from Militant-Extremist Groups (from Saucier et al,

2009)

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