Why Experience Matters: Stress Inoculation in Active Threat Assessment

Vaccines are used in medicine to help our body’s build up protections against disease. Protections which safeguard us if we are exposed. The same concept can be applied to preparing first responders to deal with stressful situations – this is often called stress inoculation.

In medicine, vaccinations involve exposing the patient to weaker forms of disease to develop resistance.  This exposure produces antibodies and physically prepares the body for future attacks. In social psychological research on stress, this “inoculation” involves exposing the trainee to moderate forms of the stress to help them deal with more stressful situations in the future. Your trainees who deal with stressful situations should get trained in ways that prepare them to do so.

Full disclosure, I am a researcher, and I have never been exposed to the kinds of high risk or violent situations dealt with by law enforcement. But, I do have some experience dealing with stress. I am an experienced skydiver (with more than 1,100 jumps over the past 20 years). In skydiving, when the last time you have jumped (a.k.a. currency) really matters.


If I haven’t jumped in a few months, I can feel it. My heart rate increases, my hands have a bit of a shake, and I get butterflies in my stomach. My cognitive abilities decrease. In short, I get dumb and scared. 

But if I have jumped recently, this doesn’t happen – my brain and body resist the stress. When I am less stressed, I process more of what is happening around me and make better decisions.  Having jumped recently inoculate me against the stress and fear associated with a somewhat dangerous activity.

Ok, enough about skydiving - let’s get back to stress inoculation and its application to police training, preparing officers for a stressful situation, or even to identify potential threats.

Stress Inoculation and Training

Stress Inoculation is used by both councilors and police trainers to help prepare people to deal with stressful situations.

From a therapeutic perspective, stress inoculation therapy (SIT) can help people deal with stressful events. It is used to help with Post-Traumatic Stress Disorder (PTSD) and help people overcome addictions. In therapy, SIT has three phases (educating about stress and harmful coping mechanisms), skill acquisition and rehearsal (learning skills to deal with a stressful event that occurs), and application and follow-through (opportunities to practice).

For law enforcement, stress inoculation training can involve exposing recruits to gradually increasingly stressful situations that they are likely to face on the job; situations involving force, pepper spray, and fighting while injured or partially incapacitated. Situations that these recruits have never experienced, but could occur while on duty. Stress inoculation training will help the recruits to function in stressful situations and react appropriately and effectively.

Research has shown that law enforcement officers who undergo marksmanship and tactical training while experiencing high levels of anxiety are less affected by anxiety when later tested under the same conditions (Honig and Lewinski, 2008; Oudejans, 2008; Nieuwenhuys, & Oudejans, 2011).

Stress and Behavior

Stress impacts our behavior and the behavior of those around us. We can feel it and even see it in others. People who are stressed may shake, have involuntary facial cues (sweating, red face, bulging veins, blinking, licking of the lips and fast eye movement), or they may have a noticeable pulse of the carotid artery on their neck (Fernandes, Portugal, Alves, Campognoli, Mocaiber, and David, 2013).  These behaviors are often involuntary and occur due to a rapid increase neurochemicals and hormones in the body during a fight or flight situation.


Individuals vary in the frequency and intensity of stress behaviors they exhibit; when stressed, they may show one behaviors, none at all, or many. One of the reasons behavior baselines are likely to vary is stress inoculation (Deyoung, 2009; Honig and Lewinski, 2008).

For an experienced drug smuggler, this might mean they can interact with law enforcement without displaying signs of nervousness or distress. A young person carrying an illegal handgun for the first time who is stopped by the police may be shaking, sweating, and repeatedly blinking their eyes.

 Active Threat Assessment and Stress Inoculation

Active threat assessment involves identifying people who are carrying weapons and may have an intent to cause harm. Stress inoculation is relevant to active threat assessment training in two ways – both in the provision of training as well as in the identification of someone who is a potential threat.

This is why we make sure our trainees learn how to use these active threat assessment skills throughout an encounter with a person of interest and allow them to practice these skills. Our first responders have plenty of stress to deal with – good training can help officers to react appropriately and effectively during encounters. These keep both them and the public safe.

Behavioral cues associated with stress are one set of threat indicators that can be used to identify an active threat. Now, we all know that stress during an encounter with LE is NOT a sign that someone is a threat; people get stressed around police for a variety of reasons unrelated to criminal intent.

Regretfully, we didn’t have as much opportunity to explore in-depth how stress impacts the behavior of potentially threatening individuals in this post and how these cues can be used to identify potential threats. But you can learn more about active threat assessment and threat indicators in our free 1-hour online Introduction to Active Threat Assessment Course.



Deyoung, B. (2009). Bullet-Proofing the mind. Law Officer, 4(3), 1-5.

Honig, A. and Lewinski, W. (2008). A survey of the research on human factors related to lethal force encounters: Implications for law enforcement training, tactics, and testimony. Law Enforcement Executive Forum, 8(4), 129-152.

 Khillah, Amir. (2017. Why stress inoculation is critical for police recruits. Policeone.com. Obtained February 2019 from https://www.policeone.com/Officer-Safety/articles/458426006-Why-stress-inoculation-is-critical-for-police-recruits/

Mills, H., Reiss, N., and M. Donbeck. (ND). Stress Inoculation Therapy. Obtained February 2019 from https://www.mentalhelp.net/articles/stress-inoculation-therapy/.

Nieuwenhuys, A., & Oudejans, R. R. (2011). Training with anxiety: short-and long-term effects on police officers’ shooting behavior under pressure. Cognitive processing, 12(3), 277-288.

Oudejans, R.R. (2008). Reality based practice under pressure improves handgun shooting performance of police officers. Ergonomics, 51, 261-273. 

Tull, M. (2018). How to Manage PTSD Stress With Stress Inoculation Training. Verywellmind.com. Obtained February 2019 from https://www.verywellmind.com/stress-inoculation-training-2797682.

Nathan Meehan Ph.D.