What Is Cannon Bard Theory?

Medically Reviewed by Smitha Bhandari, MD on July 19, 2023
3 min read

The Cannon-Bard theory of emotion proposed the idea of the fight or flight response. It’s leading question: When faced with a potentially dangerous scenario, what do your instincts tell you to do?

The Cannon-Bard theory states that the lower part of the brain, also called the thalamus, controls your experience of emotion. At the same time, the higher part of the brain, also called the cortex, controls the expression of emotion. It is believed that these two parts of the brain react simultaneously. This theory was proposed in the 1920s and early 1930s by Walter B. Cannon and Philip Bard. It’s also referred to as the “fight or flight” response.

Stress begins in your brain and your senses communicate potential dangers to it. For example, you may see a car coming toward you or hear a sudden loud sound. The Cannon-Bard theory proposes that your amygdala processes what you see and hear, translating possible danger to the hypothalamus.

Your amygdala processes emotions. When it communicates potential danger, your brain has a stress response to stay and fight the danger or run away.

Once your amygdala initiates a distress signal, your hypothalamus alerts your sympathetic nervous system by sending signals to your adrenal glands. Adrenaline begins pumping through your veins, quickly resulting in:

  • Faster heartbeat
  • Higher pulse rate
  • Increased blood pressure
  • Faster breathing
  • Heightened senses
  • Alertness

Each of these physiological responses happens so quickly that you aren’t aware at first. Instead, you’re acting instinctively. Hundreds of years ago, our instincts kept us safe. Today, we face fewer real dangers, yet our fight or flight response may still be triggered by something.

Fight or flight response adapts as your environment does. Hundreds of years ago, you may have been scared of wild animals that threatened to attack you. Instead of spending time making a logical choice based on your scenario, your brain decided for you — run, or stay and fight.

In today’s world, the fight or flight response may come in less dangerous situations. For example, your boss at work asks you to come into their office. You immediately think something is wrong, and it triggers your glands to release adrenaline. You become defensive and may feel the need to walk into the office with your guard up, ready to fight.

Alternately, past trauma or PTSD can elicit a fight or flight response. Your memories are often grounded in your senses. You remember what you saw, felt, and heard at a particular time. If you see or hear something that reminds you of a traumatic experience, your brain may trigger the fight or flight response.

This happens in an effort of self-preservation to protect you from the same trauma again. Fortunately, repeated trauma will likely not occur. Therefore, you have to focus on calming yourself down so that the stress doesn’t continue to affect your day.

Relaxation techniques. In establishing the theory of fight or flight, concerns were raised about the amount of time your body spends under stress. The Cannon-Bard theory states that if you find yourself experiencing the symptoms of fight or flight, take a minute to calm down.

Training your mind. Over time, you can train your brain to react with less eagerness if there isn’t any danger around.

Mental stress. Fight or flight is great because it’s an innate survival mechanism. However, if you are constantly facing “threats” that cause you stress, it can lead to poor health outcomes. Stress can become chronic if not properly managed.

Nervous system issues. When your body focuses its energy on responding to threats, your nervous system takes a hit. This may leave you feeling unstable and lead to chronic health problems.

If you pay attention to your subconscious response to threatening situations, you can learn a lot. If your stress levels remain too high, it’s a sign that your sympathetic and parasympathetic systems aren’t working together. You can seek help from a professional mental health provider to learn how to better manage stress.