to American national security. Understanding the
causes, motivations, and determinants of terrorist
behavior poses an enormous challenge in countering
that threat, leading to a heightened interest in the
“psychology of terrorism.” This entry focuses on the
psychological dimensions of terrorist behavior, de-
emphasizes the analysis of sociologically based expla-
nations (sometimes referred to as root causes) or
macrolevel economic and political theories, and does
not address the psychological effects of terrorism.
After decades of social science research, no single
theory of aggression has gained ascendance as an
explanatory model for all types of violence. Terrorism
is a distinct form of violence, although the basic ques-
tion of how best to define terrorism has itself been a
vexing problem. For heuristic purposes, though, most
agree that terrorism would include acts of violence (as
opposed to threats or more general coercion) inten-
tionally perpetrated on civilian noncombatants with
the goal of furthering some ideological, religious, or
political objective.
Issues of intent, tactics, motive, ideology, and legit-
imacy of targets all add complexity and plurality to
the construction of terrorism as a form of violence and
challenge the emergence of a unifying explanatory
theory. Commenting on the search for a master expla-
nation of terrorism generally, Walter Laqueur has
insightfully observed that there exist “many ter-
rorisms” and that the factors that cause, sustain, or
weaken them may vary greatly for different groups in
different contexts at different points in time. From a
psychological perspective, the psychiatrist Jerrold
Post believes that there is not one terrorist psychology,
but multiple terrorist psychologies.
Psychological theory and research on terrorism has
evolved considerably since the 1960s. The earliest line
of work was drawn principally from psychoanalytic
theory and tended to focus on narcissism and hostility
toward parents as explanatory variables. More recent
explanations have moved away from this approach. A
summary of the more contemporary body of profes-
sional literature on the psychology of terrorism is out-
lined below and framed around a series of functional
questions.How and why do people enter, remain in, and leave ter-
rorist organizations?Research on terrorists and violent
extremists who adhere to a broad range of ideologies
shows that the pathways to, and motives for, terrorism
are quite varied and diverse. Among the key psycholog-
ical factors in understanding whether, how, and whichindividuals in a given environment enter the process of
becoming a terrorist are motive and vulnerability. By
definition,motiveis an emotion, desire, physiological
need, or similar impulse that acts as an incitement to
action, and vulnerability refers to susceptibility or
liability to succumb, as to persuasion or temptation.
Regarding motive, researchers have begun to distinguish
between the reasons for joining, remaining in, and leav-
ing terrorist organizations, finding that motivations
may be different at each stage and not even necessarily
related to each other. Regarding vulnerability, there
do appear to be some common vulnerabilities and per-
ceptions among those who turn to terrorism—perceived
injustice, need for identity, and need for belonging,
though certainly there are persons who share these per-
ceptions but do not become terrorists.
In 2006, at Pennsylvania State University, an
Advanced Research Workshop was convened of pro-
fessionals who study the psychology of terrorism. The
common “risk factors” for terrorism identified by the
participants of the workshop included the following:- Perceptions of isolation or alienation from general
society - Perceptions of individual or group humiliation, injus-
tice, shame, or dishonor - Social isolation
- Need for identity and desire to belong
- Sense of disillusionment with the available
alternatives - Ideology that legitimizes terrorism
- Role models and heroes
- Sense of being or identifying with victims
Promising areas of inquiry have focused on com-
mon stages and processes in adopting extremist ide-
ologies rather than on the content of the motive or
justification per se. Three contemporary theories
describing the adoption of extremist ideologies
include Randy Borum’s generic four-stage terrorist
mindsetmodel, which attempts to explain how griev-
ances and vulnerabilities are transformed into hatred
of a target group and how hatred is transformed—for
some—into a justification or impetus for violence.
Also recently introduced is Ali Moghaddam’s stair-
case to terrorismmodel, in which he describes a con-
vergent (i.e., fewer people proceed to each successive
stage), five-step progression that transforms the per-
sonal experience of adversity into violent terrorist
action. Using a more socially based framework in a
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