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How We Process Under Pressure: Stress and Automatic Behavior

Under high stress, our minds may go on "autopilot" with disastrous results.

Key points

  • Modern research demonstrates what to expect, psychologically, when one experiences extreme stress.
  • Extreme stress can force a person to rely on old habit patterns, some of which may prove catastrophically wrong.
  • Successful training depends on helping a person create automatic habits that are useful across a reasonable spectrum of situations.
Matthew J. Sharps
Source: Matthew J. Sharps

In our last Forensic View, we began an examination of the changes in cognition and perception that occur when we’re under stress, including the extreme stress often encountered by law enforcement and other first responders. Today, we’ll start our look at the most important factors involved, including one that can be life-threateningly important: the tendency to go on “automatic pilot.”

Under high stress, we enter the human fight-or-flight response, in which a heightened state of physiological arousal, inherited from the ancient world to deal with physical emergencies, results in increased strength and endurance; but the same response can reduce perceptual and cognitive capacities in specific areas.

This behavioral complex worked pretty well in the ancient world; but in the modern world, as we saw in our last Forensic View (12/17/21), the behaviors you might use to fight or to flee from a predator are often completely inappropriate in board meetings or at the breakfast table. Wild war cries and violence, so useful in dealing with sabertooth tigers, have entirely different consequences today than in the ancient world; in the modern world, such behaviors get you fired, or you get to meet your spouse’s divorce lawyer.

Everybody knows that typical fight-or-flight behaviors are big problems in most modern settings. So why do we keep engaging in them? Why, under extreme stress, do we frequently fall back on our worst habits?

Diminished function of the prefrontal cortex

When we come under stress (e.g., Sharps, 2022), our body reallocates our blood resources differently. Far more blood goes to our muscles, for obvious reasons, resulting in fewer resources available to our brains. However, which parts of the brain get those diminished resources is further determined by typical emergency demands. The parts of the brain which tell us what we’re seeing, and where it is, really need to be kept on high alert. This is also true of the brain parts that control our movement and movement perception; so ultimately, the part of the brain that is essentially short-changed the most is the part that's less involved in these basic functions: the prefrontal cortex.

Loss of cognitive flexibility

The prefrontal cortex does most of our higher-order thinking and decision-making. In the ancient world, diminished prefrontal cortical function was often probably not as much of a problem—dealing with a ravening sabertooth tiger presents very little need for abstract thought. But in more complex if less lethal environments, like the boardroom or the breakfast table, subtle, complex decision making, requiring cognitive flexibility, is exactly what we need; and these activities are largely the province of the prefrontal cortex.

Which, under extreme stress, has more or less closed up shop and gone on vacation.

Examples of when "automatic pilot" leads to failure

With diminished prefrontal function, we tend to fall back on less optional, less flexible behaviors—the habits of mind that arise from more ancient, less flexible brain structures. Our behaviors become more automatized. This is the nature of “automatic pilot” (see Klinger, 2004; Grossman & Christensen, 2004). Under stress, we tend to go with our ingrained habits, whether they’re particularly useful or not.

The world of law enforcement provides a number of terrible and tragic examples of this. Take the infamous 1970 Newhall Incident, in which officers of the California Highway Patrol were ambushed by heavily armed attackers. Forensic analysis indicates that one officer might have been able to dispatch the assailant who killed him if he’d taken only the time needed to put one or two rounds into his emptied revolver. Instead, he took the time to reload the weapon to its full six-round capacity. This gave his attacker the extra time needed to murder him.

Why did the officer do this? Full six-round reloads, at that time, were standard on the firing range. Under the extreme tactical stress of a gunfight, the officer fell back on his training—and that training resulted in a lethally incorrect series of automatic actions in the real world.

There are many other examples. Grossman and Christensen mention instances in which officers under fire died with empty shell casings in their hands, wasting precious combat time to preserve those casings rather than simply dropping them on the ground, “dying in the middle of an administrative procedure that had been drilled into them” (2004, pg. 72). In a case discussed in Sharps (2022), an officer who had carefully practiced leaping behind cover before firing, automatizing this useful tactical behavior, survived a shooting incident and successfully defended himself. Another officer, in the same incident, did not have this covering behavior in his “automatic pilot” repertoire; standing upright as he would have at the firing range, he was murdered.

Forensic and military history abounds with these examples (e.g., Forensic View, 11/13/20; Sharps, 2022), but the lesson, for law enforcement officers and other first responders, is clear. Your training must reproduce the reasonable spectrum of situations that you will encounter in the field as closely as possible. Under tactical stress, you will behave with direct reference to “automatic pilot,” to whatever habits your experience and training have created.

If your automatic, trained behaviors are appropriate to actual field situations, you will succeed. If not, there is a strong possibility of lethal failure.

These forensic realities have a lesson for the rest of us as well. In tense situations, whether boardroom or breakfast table, we should make it automatic and habitual to pause; to consider whether what we are about to do is a good idea or a bad one, and to bring the prefrontal cortex, however briefly, back from its vacation to consider whether a given habitual response might precipitate loss of job or spouse.

It is possible to create useful automatic habits, as well as the catastrophically negative ones we’ve dealt with here. Successful training is predicated on this point. We will consider this in future posts.


Grossman, D., & Christensen, L.W. (2004). On Combat. PPCT Research publications.

Klinger, D. (2004). Into the Kill Zone: A Cop's-Eye View of Deadly Force. San Francisco: Josey-Bass.

Sharps, M.J. (2022). Processing Under Pressure: Stress, Memory, and Decision-Making in Law Enforcement. Flushing, NY: Looseleaf Law Publications.

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