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The Thomas Theorem: Frontline response to excited delirium


The Thomas Theorem is a fundamental law of sociology that can assist law enforcement personnel in their interactions with subjects experiencing excited delirium as well as mental illness.

The Theorem states that if an individual believes his situation to be real, the consequences of that belief will determine his response (Thomas & Thomas, 1928)1. In other words if the subject believes Elvis is coming for dinner you can expect to be asked to provide crowd control. Likewise, if the subject believes he is in immediate peril, he may behave as though his death is imminent.

People with acute mental illness (and those experiencing excited delirium) will not appreciate that their thoughts and beliefs are unusual, let alone unreal. Some subjects firmly believe what their mind is telling them — their food is poisoned; there is smoke coming from the basement; a “hit man” is hunting for them. Their disconnect with reality is going to be difficult, if not impossible for a uniformed police officer to resolve without guidance and/or training.

A quick review of excited delirium indicators is in order. These indicators can include combinations of the following:


  • bizarre and/or aggressive behavior
  • acute onset of paranoia
  • impaired thinking
  • panic
  • disorientation
  • shouting
  • hallucinations
  • violence towards others
  • unexpected physical strength




Hallucinations can be auditory, visual, or tactile. So lets examine how the Thomas Theorem can impact a person who is hallucinating — particularly one who perceives that he or she is about to be harmed. Such beliefs would make it reasonable for the subject to become aggressive in self-protection. Hallucinations can impair thinking and may result in disorientation (the subject thinks he is somewhere else or unaware of his surroundings). 

Hollywood provides several good examples of vivid hallucinations. When you're watching a film depiction of a hallucination, it's easy to understand how a person believes the reality of something taking place before his very eyes, because you, as a sympathetic viewer, are likely accepting the images before your very eyes.

In A Beautiful Mind, Russell Crowe plays a mathematical genius (John Nash) who interacts with three particular characters throughout the film. Each of these people (Agent William Parcher, Nash’s college roommate, Charles, and Charles' niece, Marcee) is a creation of Nash’s mental illness (Howard, 2001).

The blockbuster Raiders of the Lost Ark provides another good example. Think of the scene where the Nazi soldiers open the Ark. Eerie glowing spirits emerge from within, and first terrorize, then kill the bad guys by melting their faces and making them explode (Spielberg, 1981). The subjective ability to interweave hallucinations into the fabric of a person’s existence is remarkable — part of the experience is objectively real while another part is contrived, however perceived as genuine by the subject.

Here's the point: What behavior would you expect from a subject who believes that your face is melting? What if they see glowing spirits swirl around your head or emerge from within your uniform? This is where understanding the Thomas Theorem can help you interact with the subject — if their perceptions are believed to be real, then the consequences of your face melting, or of spirits swirling out from your clothing are also real.

What would you do if you saw such events unfold with your own eyes and believed them to be true? The subject may become terrified of you, and either run away or attack. If the situation were real, their reaction would make perfect sense. The problem is that we cannot tell what another person is thinking or how they are experiencing the situation.

This is likely how other features of excited delirium factor into the situation. People who believe they are about to be harmed or believe they are in danger can produce unexpected physical strength due to the sudden adrenalin rush that accompanies the fight-or-flight response 2.

The sudden onset of paranoia could be due to misinterpretation of the events and/or hallucinations. These altered perceptions could explain the panic, shouting, and ultimately the violence displayed by subjects experiencing excited delirium. So, when you interact with a person in crisis, maintain a safe distance and listen to what they say.

It's critical to understand the distorted cognition behind a subject's actions and behaviors, otherwise, their failure to comply with orders like, "get down on the ground," "get on your knees," or "come over here so I can talk to you" would (rationally) lead you to believe that they are a willfully direct threat.

What to do

If, on your arrival, the subject seems to be in crisis, request additional units to assist. Training communications personnel to recognize the hallmarks of excited delirium can result in an early coordinated medical/law enforcement response.

A person experiencing an excited delirium may have an altered perception of reality; could be very frightened; which may activate the fight or flight response. This person requires medical attention and will likely strenuously resist any efforts to gain control of his or her movements. If not already en route, call for medical assistance as soon as you realize the scope of the situation.

Remember, these subjects are extremely strong and seem to feel no pain. Baton strikes and pepper spray do not have their expected effect. Conducted energy devices (TASER©) can provide a window of opportunity during which officers can establish control and secure the subject’s hands with handcuffs. Secure their legs and roll them into a position where they can cause themselves the least harm. Subjects in excited delirium are known to bang their face and head against the ground or nearby objects. Rolling them onto their side and placing an emergency blanket under their head should limit the subject’s injuries. Again, get them to a hospital as soon as possible.

Consider the Thomas Theorem when interacting with persons who have a mental illness. Their perceptions are as real to them as your reality is to you.

Additional Resources


Local experts on how to respond to someone experiencing an acute mental health crisis are nurses within your community skilled in caring for mentally ill patients. They can be a great resource for you and they will likely have lots of examples for you to consider.I continue to recommend two recent texts on excited delirium (Di Maio & Di Maio, 2005; Ross & Chan, 2006). The Di Maio book includes a chapter that deals with how law enforcement officers might handle an excited delirium case.

An outstanding program on mental illness and the associated difficulties some people live with is FRONTLINE’s “The New Asylums.” This award winning program can be viewed on-line at http://www.pbs.org/wgbh/pages/frontline/shows/asylums/view/. While the information comes from a correctional setting, I found valuable links to front-line response issues. As you watch the program keep the Thomas Theorem in mind. Appreciating the difference between your perception of reality and the perceived reality of people the inmates represent will benefit you and your community. Remember, everyone belongs to someone.

NOTE:  I wish to thank Dr. Ivanhoe Becker MB.ChB., CCFP, for his guidance and assistance in reviewing this paper.




Di Maio, V. J. M., & Di Maio, T. G. (2005). Excited delirium syndrome: Cause of death and prevention. Baca Raton, FL: CRC Press.
Howard, R. (Writer) (2001). A beautiful mind [Film]. In B. Grazer & R. Howard (Producer). USA: Universal Pictures.
Spielberg, S. (Writer) (1981). Raiders of the lost ark [Film]. In F. Marshall (Producer). USA: Paramount Pictures.
Thomas, W. I., & Thomas, D. S. (1928). The child in America: Behavioral problems and programs. New York: Alfred A. Knopf, Inc.

“If men define their situations as real, they are real in their consequences” (p.572).

I believe that the simplest way to explain excited delirium is a fight or flight response gone awry.


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