Acute Stress Response and Deception Detection

A useful tool regarding lie detection.

Posted Jan 26, 2020

Also called the "fight-or-flight response," this condition, theorized by the noted psychologist and former chair of the Harvard Medical School department of psychology Walter Bradford Cannon, is the response to a threat, or perceived threat, to attack, harm, death, or similar self-preservation endangering conditions.

A human exposed to one of these threats, according to Cannon, will initiate a reaction to do one of two actions: stay and engage the threat (fight) or attempt to avoid the encounter and flee (flight)—the activation of the sympathetic nervous system.

Because the body is attempting to prepare for either option, beginning at the amygdala at the base of the brain, a series of reactions are set in motion. This reaction causes the increase of blood sugar, blood pressure increase, and an increase of energy. Energy is required for either option, fight or flight.

The bodily signs caused by the acute stress response is important to investigators and those training in deception detection.

When cornered in a threat situation, the acute stress response enacts and can cause individuals to manifest visual indicators that they are, indeed, under stress and helps provide investigators with indicators that those being questioned may be now in a stressful situation—a situation that may require deception.

For instance, questioning an individual regarding a crime where the interrogated was a part, and where he wants to distance himself from involvement, a certain question may activate an acute stress response revealing certain indicators that the individual is under stress.

Care must be taken, however, to understand the difference between a universal response versus an individual response. In a universal response, the individual is nervous—acute stress response—from the very beginning of the questioning and stays nervous and stressed throughout the questioning. universal responses are moreover meaningless regarding deception detection and should give way to the more specific individual responses. In an individual response, the subject will have a normal demeanor initially, but become nervous and stressed at the asking of a particular question. This response indicated that a particular question activated the acute stress response and is significant to investigators as it may indicate a deceptive answer will ensue.

Signs of someone exhibiting signs of an acute stress response may include pupil dilation; nervousness; pale skin; increased respirations; dry mouth; increased blinking rate; the need to urinate; and, due to blood flow change, the need of the individual to rub or scratch his or her ears or nose.

The accurate observation and application of the indicators given by the acute stress response by an individual is a major tool for the investigator or individual seeking to discern if someone is being deceptive or lying.


"Understanding the Stress Response." (2018, May 1). Retrieved from