February 2017 – The events of September 11, 2001 fundamentally altered the psychological landscape of society in ways that are unprecedented. Its effects continue to reverberate in contemporary culture, and are exacerbated by new terrorist attacks, and the very real and ongoing prospect of future violence. As a result, our society has pivoted in many ways – with much greater attention now to securitization and defense as a means of keeping us safe from these threats. This becomes immediately apparent when traveling through airports, entering large sports stadiums, or simply watching the evening news. At its core, terrorism is inherently a psychology of fear – where uncertainty and insecurity are used instrumentally by some to affect the larger political and social zeitgeist for the many. In spite of this, only recently have we begun to explore the impact of more chronic fear, worry, and insecurity (Sinclair & Antonius, 2012).
Prior to the September 11, 2001 attacks, research on the psychological effects of terrorism was relatively sparse and specific to regions such as the Middle East and Northern Ireland – which in turn has led some to debate its generalizability. However, following these attacks there was a proliferation of epidemiological and other population-based studies in the United States, which examined how people were impacted psychologically (for a comprehensive review see Sinclair & Antonius, 2012). Notably, the vast majority of this research explored prevalence rates of various psychiatric disorders / symptoms in the general population and areas immediately impacted, using clinical frameworks such as the Diagnostic and Statistical Manual of Mental Disorders (DSM-IV; American Psychiatric Association, 2000).
In aggregate, this body of research demonstrated an immediate and significant spike in various types of psychiatric conditions (e.g., depression, anxiety, trauma reactions) in the general US population following the attacks. For example, it was determined that approximately one-third of people directly exposed to a terrorist attack will subsequently experience clinically significant distress, such as Acute Distress Disorder and/or Post Traumatic Stress Disorder (Friedman, Hamblen, Foa, & Charney, 2004; Lee, Isaac, & Janca, 2002). There were also multiple national studies highlighting increases in psychiatric symptoms (e.g., PTSD, depression, substance misuse, etc.), irrespective of whether people were immediately exposed to the attacks themselves (Sinclair & Antonius, 2012). In part, this has been explained in terms of a mass exposure effect phenomenon, where people across the country were vicariously traumatized through perpetual media exposure (Ahern, Galea, Resnick, & Vlahov, 2004; Marshall, Bryant, Amsel, Suh, Cook, & Neria, 2007; Jhangiani, 2010).
Research over the last 15 years has also demonstrated that many variables interact in explaining how people react to terrorism emotionally, including: proximity to the attacks, extent of subsequent re-exposure through the media, pre-existing psychiatric vulnerabilities, level of social supports / interpersonal connections, income and education, chronic disease, degree of life stressors, etc. (Bonanno et al., 2006). Collectively, this body of work highlights how people directly exposed are at greater risk for developing some form of psychopathology, but also that people in the general population remain vulnerable – underscoring the unique role that media plays in terms of exposure.
Perhaps most surprising, numerous longitudinal studies demonstrated a gradual, normalizing trend in rates of psychopathology over time. Taken together, this body of work suggests that prevalence rates for most psychiatric conditions returned to pre-September 11, 2001 levels at roughly 6-12 months following the attacks – a return to normalcy, if you will (Sinclair & Antonius, 2012; Sinclair & Antonius, 2013). There are some exceptions to these trends, of course – for example, those most proximate to the areas affected (e.g., lower Manhattan) tended to exhibit a greater degree of psychiatric disturbance, which persisted over longer periods of time. However, as a whole this research indicates that we as a nation have essentially returned to normal.
Fear as Distinct from Psychopathology
In spite of this “new normalcy,” there is evidence that many remain fearful and worried about the prospect of future terrorism, and these fears impact people in meaningful ways. For example, numerous national polling and social science research studies have demonstrated varying levels of fear and worry in the general US population, which continue to persist irrespective of psychopathology (Boscarino, Figley, & Adams, 2003; Boscarino, Adams, Figley, Galea, & Foa, 2006; Eisenberg et al., 2009; Pyszczynski et al., 2003; Richman, Cloninger, & Rospenda, 2008; Schuster et al., 2001; Silver et al., 2002; Silverleib, 2008). These fears are perpetuated by ongoing threats / warnings that are communicated by the media and those in government, and have been found to be associated with increased levels of distress and behavioral change (usually avoidance-type behaviors), and fluctuating levels of trust in government (Kramer, Brown, Spielman, Giosan, & Rothrock, 2003; Sinclair & LoCicero, 2007; Sinclair & LoCicero, 2010).
Sinclair and Antonius (2012) recently provided a more circumscribed overview of the psychological effects of terrorism, as well as how fear specifically may impact people uniquely and independent of psychopathology. For example, elevated fears of terrorism have been shown to be associated with greater levels of behavioral avoidance, physiological stress, and symptoms of anxiety and depression (Sinclair & LoCicero, 2007; Sinclair & LoCicero, 2010). Perhaps more alarmingly, Shenhar-Tsarfaty and colleagues (2014) recently conducted a survey of over 17,000 Israeli citizens undergoing routine annual medical examinations, and found that elevated fears of terrorism were associated with increased heart rate and other biomarkers of inflammation, which have been shown to be strongly predictive of myocardial infarction and stroke – and thus increased mortality risk.
Taken together, these findings suggest that while prevalence rates for most psychiatric conditions essentially returned to baseline, anticipatory fear and insecurity surrounding future terrorism have remained prominent. Of note, this dynamic of fear reactivity is one primary reason why the US Department of Homeland Security revised its color-coded alert system in 2011 – as a means of providing greater specificity and detail surrounding potential threats, and reducing anxiety and anticipatory fear. This change was in reaction to criticism that a change in threat level, as denoted by an “elevation” in color code, did much to prime people’s fears that a threat was imminent, but little to help people mitigate these fears / threats through concrete steps they could take to feel safe. As such, the current system (implemented in 2011) sought to reduce this fear priming by eliminating the color-coded differentiations, and increase locus of control by providing more specific information as to the nature and target of the threat (for example, whether it related specifically to the transportation system).
Do Our Clinical Assessment Frameworks Need to Change?
To sum up, it becomes apparent that the research on the psychological effects of terrorism has presented two very disparate messages. On the one hand, society has “normalized” in terms of psychopathology rates and we now appear as we did prior to September 11, 2001. On the other hand, many people remain fearful (among other emotions), and these experiences influence how people live their lives – for example, where they work and live, with whom they socialize, amenability to taking public transportation, and the list goes on. As summarized above, these fears also have the potential to impact individuals’ physical and mental health in ways that are meaningful.
Some have argued that conventional mental health models may not be sufficient in assessing the psychological effects of terrorism, particularly in terms of the pervasive sense of anticipatory fear and worry that manifests (Marshall et al., 2007). For example, when evaluating for conditions such as PTSD using diagnostic frameworks like the DSM-IV (APA, 2000), the focus is primarily on symptomatology that is secondary to a discrete traumatic event (e.g., terrorism). In fact, direct exposure to a traumatic event is requisite for a diagnosis to be made. In contrast, there really is no mechanism in the DSM or other frameworks for evaluating the fears, worries, and insecurities that may arise in anticipation of future violence / terrorism.
Taking this one step further, Marshall and colleagues (2007) also discuss how traditional mental health frameworks usually consider trauma exposure in terms of a “bull’s eye model” – where those most proximate to the traumatic event will be at greatest risk of developing conditions such as PTSD, and this susceptibility decreases incrementally as distance is gained from the event. Transposed to research disseminated post-September 11, 2001, these types of models do not sufficiently explain the national spikes in PTSD and other types of trauma reactions that were consistently observed, even though most of these individuals were not directly exposed – which is again a criterion for diagnosis.
Collectively, these findings raise questions about whether existing mental health models are sufficient in explaining the psychological effects of terrorism more generally, as well as the unique phenomenon of anticipatory anxiety about future (unknown) threats specifically. Marshall and colleagues echoed a similar sentiment, noting “…the presence of persistent fears in the general population of being personally harmed in future terrorist attacks is a poorly understood phenomenon that may represent a vulnerability in the general population…” (p. 305).
Terrorism as a Unique Threat
The events of September 11, 2001 are unique in terms of how fear and insecurity were primed in the general population, and there are ways in which this reflects a new type of threat paradigm unlike any other in history (Sinclair & Antonius, 2012; Sinclair & Antonius, 2013). For example, some are quick to point out how unlikely we are to perish as a result of terrorism, and frequently juxtapose these types of threats with other common dangers we face in life that are far more threatening, at least statistically (e.g., automobile accidents, health ailments, smoking, etc.). However, there are several key features that distinguish terrorism from other threats we face, which in turn may explain the differences in fear responses (and other emotional responses) that people experience.
The first of these is locus of control. In contrast to the dangers posed by driving or heart disease, where people are able to take concrete steps to assert greater levels of (perceived) control, there is no blueprint for establishing control or prediction when it comes to terrorism. It can happen anywhere and at any time, and through an infinite number of means. Indeed, according to the most recent statistics provided by the US Center for Disease Control (through 2013), eight of the top ten leading causes of death are health-related (e.g., heart disease, cancer, stroke, etc.) (CDC, 2016). However, the locus of control one may experience across these different threats is likely to vary significantly.
In the case of illness or automobile accidents, individuals are more able to pinpoint the threat and take measures to mitigate it – whether through improving health (e.g., through increased exercise, diet modification, medication, etc.) or putting on seatbelts and/or driving slower when operating an automobile. However, in the case of terrorism, there is a significantly reduced sense of control and fewer options available for people to feel in control. As a result, people may respond in a variety of ways – often through some form of avoidance (i.e., avoiding flying or using public transportation, crowded public gatherings, etc.). Terrorist attacks are often perceived as random and elusive, with varying targets, methods of attack, and perpetrators. As a result, a person’s sense of agency in mitigating threat is significantly reduced. This likely explains the sense of cognitive dissonance people feel when told to live their lives normally.
The second feature is the catastrophic nature of the threat. Although terrorism may result in fewer overall mortalities statistically than other threats faced in everyday life, there are ways in which it is unique – both in terms of the sensationalism involved (e.g., beheadings, mass shootings) and potential scope (e.g., the prospect of nuclear / biological / chemical threats). Fear and anxiety are not only reactions to the discrete events themselves, but also to the potential for future catastrophe that is far worse. The events of September 11, 2001 were unique in terms of the sheer destruction and lives lost, with no other event on US soil even approximating this level of devastation – all of which raised the specter of terrorism in a manner never seen before.
However, it was also the national discussion that ensued in the following months and years which really catapulted terrorism into the public’s awareness. Frequent warnings from government officials (and others in the media and academia) about the possible use of biological, chemical, radiological, and even nuclear weapons bombarded the public and led people to consider catastrophes far worse than those observed on September 11, 2001. For example, in his 2004 book, Nuclear Terrorism, Harvard Professor Graham Allison noted, “…a nuclear terrorist attack on America in the decade ahead is more likely than not” (p. 15). Thus, while most attacks to date have been relatively smaller in scale, the perceived potential for far greater catastrophe and destruction have become boundless and terrifying in and of themselves.
Slovic (1987) highlighted these two factors when discussing how people develop heuristics for appraising risk in their everyday lives. Whereas Dread Risk relates more to the catastrophic and destructive quality of the threat faced, Unknown Risk has to do with the lack of control and predictability one experiences when faced with these threats (also reviewed by Marshall et al., 2007). Based on their configuration, a person’s level of perceived risk and subjective fear will vary across a continuum of threats. While these heuristics have been applied to many types of situations / threats, they are especially relevant to terrorism and may help to explain the pervasive sense of fear experienced by many post-9/11.
The third feature is the prospective, ongoing nature of the threat. Whereas disorders such as PTSD, by definition, examine symptom clusters (anxiety, avoidance, hyper-arousal) that manifest relative to a specific traumatic event(s) (American Psychiatric Association, 2013), terrorism is unique in terms of how it elicits anticipatory fear of what is to come. Thus, in addition to the catastrophic quality described above, there is also an enduring (and even never-ending) aspect to it – with no concrete parameters to indicate a beginning and an end. The threat continues to exist regardless of whether there are specific attacks, and fuels a more chronic and perpetuating insecurity within people.
Some have termed this phenomenon a Pre-Traumatic Stress Syndrome to highlight the fear and anxiety associated with a future, probabilistic threat that has not yet manifested (Zimbardo, 2003). These fears may vary to some degree, but are easily stirred up in the wake of new threats or attacks, and are perpetuated by ongoing threat priming through the media at a near constant rate (e.g., 24-hours new coverage, television shows and movies with terrorism themes, political rhetoric, etc.).
The fourth and final feature is the ubiquitous nature of the threat. That is to say, unlike most other dangers we face in life, where one is able to clearly identify the specific threat dynamic (e.g., driving in a car, running away from a bear, living in poor health, consuming too much alcohol), the threat of terrorism lacks a clarity and definition in a way that ignites fear. This is different from the catastrophic and perpetual qualities discussed above, and relates more to the lack of definition and ability of someone to clearly identify a threatening stimulus. The term “terrorism” itself is fundamentally unusable as a descriptor, as there are an almost infinite number of possible situations or threats that could qualify, rendering it almost meaningless. This may explain why in many ambiguous catastrophes, where cause has yet to be determined, terrorism is often among the first that needs to be formally ruled out.
Fear in Recent Historical Context
Although the imminence of national security threats has waxed and waned over the last fifteen years, the last twelve months have seen a resurgence of terrorism in western nations, with attacks in Paris (November 2015), San Bernardino, CA (December 2015), Brussels (March 2016), Orlando (June 2016), and Berlin (December 2016) to name a few. As a result, terrorism fears have reached their highest levels in the United States since 2003, with recent polling studies suggesting that nearly three-quarters of Americans believe terrorism is likely within weeks (Agiesta, 2016) and half worry that they or a loved one will be a victim of terrorism (Gallup, 2016). The ongoing terrorism threat has become a source of fear, insecurity, and even anxiety for many; and there are wide-reaching implications in terms of how these types of emotional reactions have the potential to impact public and political discourse.
Some would suggest that terrorism and national security have evolved into the most important sociopolitical issues of our time (Sinclair & Antonius, 2012), with immediate relevance to the recent 2016 United States’ Presidential election. Since the attacks of September 11, 2001, these dynamics have permeated political / public discourse in a myriad of ways, including with respect to immigration policy, second amendment rights, the Syrian refugee crisis, border protection, national security policy, the relinquishing of basic civil liberties, decisions about war, increases in hate crimes directed at those seen as responsible, and our economy to name but a few. At its core, terrorism is a complex psychology of emotion – uncertainty about the future, anxiety about victimization, fear of annihilation, anger at not being able to stem the threat, worry about change, and an infinite number of other affective experiences. It has become embedded within our collective consciousness in ways that now seem routine, pervaded our sense of culture and community in a manner that both repels and draws people together, and altered the basic fabric of our society in fundamental ways – both for better and worse.
Within the political spectrum, these emotional reactions have meaningful consequences in terms of which governmental policies are supported and enacted (Lerner, Gonzalez, Small, & Fischhoff, 2003). For example, in a large national survey of Americans in the months following the 9/11 attacks, Lerner and colleagues (2003) investigated the differential effects of fear versus anger on subsequent policy preferences. Notably, they found that fear increased future risk estimates and were more associated with precautionary, conciliatory policies aimed at mitigating risk. In contrast, greater levels of anger were associated with higher levels of optimism (and reduced sense of risk), as well as a greater preference for more punitive responses.
Research has also revealed varying levels of trust in government over time, often as a function of terrorism – with a significant spike in governmental trust observed immediately following the 9/11 attacks (Chanley, 2002). This was thought to be associated with the uncertainty and fear that many experienced in the days and months after the attacks, and sense of protection people sought from their elected officials. This pattern of findings was also observed in Spain following the 3/11 attacks on the transit system in Madrid, although was found to be short-lived with rates of trust returning to pre-attack levels by roughly seven months’ post 3/11 (Dinesen & Jaeger, 2013). Given these types of trends and questions about the role of emotions specifically, Sinclair and LoCicero (2010) formally tested whether fear was a meaningful predictor of governmental trust in a large sample of university undergraduates in 2006. As expected, they found that fear was a meaningful predictor of governmental trust even after controlling for other demographic variables.
Further illustrating the relationship between emotion and political beliefs / attitudes, Renshon, Lee, and Tingley (2015) recently published a study examining how anxiety specifically may impact political decision-making. Notably, they found that experimentally-induced anxiety led to higher levels of physiological arousal, which in turn was strongly predictive of anti-immigration attitudes. They explained these findings in terms of how people in negative affect states are more prone to interpreting ambiguous information in threatening ways. These findings have immediate implications in the current political context – specifically as it relates to the Syrian refugee crisis and border protection laws, and what seems like an increasing polarization in viewpoints on both sides of the debate.
Several studies have also examined the relationship between terrorism and engagement in political activity, where emotional reactions are hypothesized to play a significant role. For example, Robbins, Hunter, & Murray (2013) evaluated whether increased voter turnout was related to terrorism activity internationally, and found robust associations between the two. The authors highlighted the important role that emotion plays in terms of political decision-making, especially when faced with an external threat – which in turn motivates people to analyze and engage the political process more carefully. Similarly, Hersh (2013) conducted a study where he analyzed a number of governmental databases in the United States and found that relatives and neighbors of 9/11 victims became more engaged politically (e.g., election participation) after the attacks, as compared to their control counterparts – and remained so even 12 years following September 11, 2001.
Social & Political Implications
The implications of high levels of emotionality and perceived threat on our politics, government, and society at large are many and significant. The terrorism threat is quite unique in terms of the stranglehold it now has on the United States. It polarizes peoples’ perspectives and moves individuals to take even more extreme steps in order to feel safe. Following 9/11/2001, it moved people to relinquish even the most basic civil liberties to ensure protection (The PATRIOT ACT). It has led some to stockpile weapons, and others to advocate for an outright repeal of the second amendment. This year, it moved 31 United States Governors to block entry (at least temporarily) to individuals fleeing war in Syria simply because of their nationality. The threat of terrorism has even led some to consider banning an entire religious group from entry into the United States, which should give everyone serious pause – given that our country was founded by people fleeing religious persecution. Finally, the threat of terrorism pervades national security policy and the conditions under which it becomes acceptable and even necessary to go to war – all in the name of feeling safe. One could argue the threat of terrorism has fundamentally altered the fabric of our society in ways that are not consistent with how the country was originally established.
It is equally important to emphasize here that terrorism can be a catalyst for good. Some have referred to this phenomenon as Post-Traumatic resilience or growth – where people are also able to negotiate these types of difficult and painful experiences in ways that are meaningful and transcend the trauma itself (Sinclair & Antonius, 2012). It brought tremendous kindness and kinship from people and nations around the globe in the days, weeks, and months following 9/11/2001. It has also brought communities of people together, and made us forget our differences for a time. We are specifically reminded of how poignant these sentiments were as we in Boston watched the arch-enemies Boston Red Sox and New York Yankees play one another, initially following 9/11/2001 and then again in 2013 after the Boston Marathon bombings – where community and solidarity superseded any sense of rivalry or competition. In ways, this new era of terrorism has redefined what it means to be resilient, and provided new opportunities for individual and societal growth. Following the Boston Marathon bombings, it became the impetus for the Boston Strong movement and energized a city. As such, it is also important to highlight how these threats have brought people together in union and relationship in ways that are unprecedented.
As we gain distance from the recent US Presidential Election and move into the future, we must be mindful of what is at stake and how the threats we face move us in both positive and negative directions. As a society, we must be cognizant of how insidious and divisive fear (and anger) can be, as well as the many ways it can be exploited for political, social, and economic gain. The terrorism threat we face is complex and will not be mitigated by simple solutions, such as excluding an entire religious or ethnic group of people, new wars, or escalating violence. We must step back, take stock of the threats we face and fear it produces, and begin to have a thoughtful discussion about how to respond in a way that adheres to our core values and unifies us as a people. The alternative seems to be the track we are on currently, where fear breeds a never-ending sense of uncertainty and divides people in a way that is destructive. We must be proactive and methodical, as opposed to reactive and reflexive.
Note: Correspondence concerning this article should be addressed to Samuel Justin Sinclair, William James College, One Wells Avenue, Newton, MA 02459; DrJustinSinclair@gmail.com.
Agiesta, J. (2016). CNN Poll: Concern about terrorist attack at highest level since 2003. Retrieved November 5, 2016 at http://www.cnn.com/2016/06/23/politics/terror-attack-poll/.
Ahern, J., Galea, S., Resnick, H., & Vlahov, D. (2004). Television images and probable posttraumatic stress disorder after September 11. The Journal of Nervous and Mental Disease, 192, 217-226.
Allison, G. (2004). Nuclear terrorism: The ultimate preventable catastrophe. New York: Times Books.
American Psychiatric Association. (2013). Diagnostic and statistical manual of mental disorders-5. Washington DC: American Psychiatric Association.
Bonanno, G.A., Galea S., Bucciarelli A., Vlahov D. (2006). Psychological resilience after disaster: New York City in the aftermath of the September 11th terrorist attack. Psychological Science, 17,181–86
Boscarino, J.A., Adams, R.E., Figley, C.R., Galea, S., & Foa, E.B. (2006). Fear of terrorism and preparedness in new york city 2 years after the attacks: Implications for disaster planning and research. Journal of Public Health Management Practice, 12, 505-513.
Boscarino, J.A., Figley, C.R., & Adams, R.E. (2003). Fear of terrorism in New York after the September 11 attacks: Implications for emergency mental health and preparedness. International Journal of Emergency Mental Health, 5, 199-209.
Centers for Disease Control and Prevention. Web-Based Injury Statistics Query and Reporting System (WISQARS) Website. http://webappa.cdc.gov/sasweb/ncipc/leadcaus10_us.html. Accessed September 22, 2016.
Chanley, V.A. (2002). Trust in government in the aftermath of 9/11: Determinants and consequences. Political Psychology, 23, 469-483.
Dinesen, P.T., & Jaeger, M.M. (2013). The effect of terror on institutional trust: New evidence from the 3/11 Madrid terrorist attack. Political Psychology, 34, 917-926.
Eisenberg, D.P., Glik, D., Ong, M., Zhou, Q., Tseng, C., Long, A., Fielding, J., & Asch, S. (2009). Terrorism-related fear and avoidance behavior in a multiethnic urban population. American Journal of Public Health, 99, 168-174.
Gallup Poll (2016). Terrorism in the United States. Retrieved November 5, 2016 at http://www.gallup.com/poll/4909/terrorism-united-states.aspx
Hersh, E.D. (2013). Long-term effect of September 11 on the political behavior of victims’ families and neighbors. Proceedings of the National Academy of Sciences of the United States of America, 110, 20959-20963.
Jhangiani, R. (2010). Psychological concomitants of the 11 September 2001 terrorist attacks: A review. Behavioral Sciences of Terrorism and Political Aggression, 2, 38-69.
Kramer, M.E., Brown, A.D., Spielman, L., Giosan, C., & Rothrock, M. (2003). Psychological reactions to the national terror alert system. The ID, 1, 67-70.
Lentini, P. (2008). Review Essay – Understanding and combating terrorism:Definitions, origins, and strategies. Australian Journal of Political Science, 43, 133.
Lerner, J.S., Gonzalez, R.M., Small, D.A., & Fischhoff, B. (2003). Effects of fear and anger on perceived risks of terrorism: A national field experiment. Psychological Science, 14, 144-150.
Marshall, R.D., Bryant, R.A., Amsel, L., Suh, E.J., Cook, J.M., & Neria, Y. (2007). The psychology of ongoing threat: Relative risk appraisal, the September 11 attacks, and terrorism-related fears. American Psychologist, 62, 304-316.
North, C.S., Nixon, S.J., Shariat, S., Mallonee, S., McMillen, J.C., Spitznagel, E.L., & Smith, E.M. (1999). Psychiatric disorders among survivors of the Oklahoma city bombing. Journal of the American Medical Association, 282, 755-762.
North, C.S., & Pfefferbaum, B. (2002). Research on the mental health effects of terrorism. Journal of the American Medical Association, 288, 633-636.
Pyszczynski, T., Solomon, S., & Greenberg, J. (2003). In the wake of 9/11: The psychology of terror. Washington, DC: American Psychological Association.
Renshon, J., Lee, J.J., & Tingley, D. (2015). Physiological arousal and political beliefs. Political Psychology, 36, 569-585.
Richman, J.A., Cloninger, L., & Rospenda, K.M. (2008). Microlevel stressors, terrorism, and mental health outcomes: Broadening the stress paradigm. American Journal of Public Health, 98, 323-329.
Ranstorp, M. (2009). Mapping terrorism studies after 9/11. In Richard Jackson, Marie Bryn Smyth, and Jeroen Gunning (Eds), Critical Terrorism Studies. London: Routledge Publishers.
Schuster, M.A., Stein, B.D., Jaycox, L.H., Collins, R.L., Marshall, G.N., Elliott, M.N., et al. (2001). A national survey of stress reactions after the September 11, 2001 terrorist attacks. New England Journal of Medicine, 345, 1507-1512.
Silver, R.C., Holman, E.A., McIntosh, D.N., Poulin, M., & Gil-Rivas V. (2002). Nationwide longitudinal study of psychological responses to September 11. Journal of the American Medical Association, 288, 1235-1244.
Silverleib, A. (2008). Poll: Terrorism fears are fading. Retrieved 12/2/2008 from http://cnn.site.printthis.clickability.com.
Shenhar-Tsarfaty, S., Yayon, N., Waiskopf, N., Shapira, I., Toker, S., Zaltser, D., Berliner, S., Ritov, Y., & Soreq, H. (2014). Fear and C-reactive protein cosynergize annual pulse increases in healthy adults. Proceedings of the National Academy of Sciences, DOI: 10.1073/pnas.1418264112.
Sinclair, S.J., & Antonius, D. (2012). The psychology of terrorism fears. Oxford: Oxford University Press.
Sinclair, S.J., & Antonius, D. (Eds.). (2013). The political psychology of terrorism fears. Oxford: Oxford University Press.
Sinclair, S.J., & LoCicero, A. (2007). Anticipatory Fear and Catastrophizing About Terrorism: Development, Validation, and Psychometric Testing of the Terrorism Catastrophizing Scale (TCS). Traumatology, 13, 75-90.
Sinclair S.J., & LoCicero, A. (2010). Do Fears of Terrorism Predict Trust in Government? Journal of Aggression, Conflict and Peace Research, 2, 57-68.
Slovic, P. (1987, April 17). Perception of risk. Science, 236, 280-285.
Zimbardo, P. (2003b). The political psychology of terrorist alarms. Retrieved February 2004 from http://www.zimbardo.com/downloads/2002%20Political% 20Psychology%20of%20Terrorist%20Alarms.pdf.