A trigger in psychology is a stimulus such as a smell, sound, or sight that triggers feelings of trauma.

What is a Trigger?

In the strictest sense of the term, trigger is used to refer to experiences that “re-trigger” trauma in the form of flashbacks or overwhelming feelings of sadness, anxiety, or panic. The brain forms a connection between a trigger and the feelings with which it is associated, and some triggers are quite innocuous. For example, a person who smelled incense while being raped might have a panic attack when he or she smells incense in a store.

The term is used more loosely to refer to stimuli that trigger upsetting feelings or problematic behaviors, and these feelings are often associated with a psychiatric condition. People who have triggers may re-engage in unhealthy behaviors when exposed to triggers. For example, a person recovering from anorexia might be triggered by photos of very thin people to begin starvation once again. Some mental health-oriented message boards and blogs put “trigger warnings” on material that might be harmful to some people. It is impossible to predict or avoid all triggers because so many triggers are innocuous, but images of violence, substance abuse, or weapons are sometimes labeled with a trigger warning.

How Are Triggers Formed?

The exact brain functioning behind triggers is not fully understood. However, there are several theories about how triggers work. Sensory memory can be extremely powerful, and sensory experiences associated with a traumatic event may be linked in the memory to this event, causing an emotional reaction even before a person realizes why he or she is upset. Habit formation also plays a strong role in triggering. People tend to do the same things in the same way. A person who smokes might, for example, always smoke while he or she is driving, and therefore driving could trigger smoking, often without the smoker’s conscious thought.


  1. Black, C. (n.d.). The triggering effect. Psychology Today. Retrieved from
  2. University of Alberta Sexual Assault Center. (n.d.). What is a trigger? Psych Retrieved from

Last Updated: 08-28-2015

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  • Abc

    June 8th, 2017 at 10:07 PM

    Does trigger stacking as described in dog behaviour apply to people too?

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