Have you ever wondered where emotion comes from? The Cannon-Bard theory says there’s a physiological explanation for it.

The Cannon-Bard theory proposes that outside events can cause emotional and physical responses at the same time.

The theory directly challenges the James-Lange theory of emotion, which states that emotions are the result of a physical reaction to a stimulating event.

Instead, the Cannon-Bard theory proposes that the feeling and the physiological expression of emotion occur independently but exactly at the same time.

Walter B. Cannon and Philip Bard developed the theory in 1927 as a direct response to the then-popular James-Lange theory of emotion.

The Cannon-Bard theory is also known as the thalamic theory of emotion related to the thalamus, a part of your brain related to sensory and motor functions. This theory suggests that external (outside the body) stimulation — negative or positive — can trigger both an emotional and physical response that starts in the thalamus.

For example, if you have a fear of spiders, seeing one crawling near your bed may cause you to feel fear and start trembling at the same time.

According to the Cannon-Bard theory, you’re not trembling because of the fear you feel and you’re not feeling fear because your body started trembling. Both happened independently at the same time as a response to the stimulus (the spider).

In other words, the theory says that it’s not the experiencing of the emotion that causes the reaction in your body or vice versa. Instead, both responses to an external stimulus happen at the same time.

The Cannon-Bard theory suggests that emotions are primarily controlled by your thalamus, an area of your brain that communicates with your peripheral nervous system and cerebral cortex.

The peripheral nervous system refers to all the nerves of your body outside of the brain and spinal cord. The cerebral cortex is the wrinkly cover, or outer layer, of your brain that regulates important functions, from your five senses to speech and memory.

According to the theory, the experience of the emotion (feeling it) starts in the thalamus, and the expression of that emotion (how your body reacts) comes from the hypothalamus. The cerebral cortex can either “allow” or “suppress” the physical expression of the emotion.

Here are a few examples of how the Cannon-Bard theory would explain emotional responses in real-world situations.

Deer runs in front of your moving car

Picture driving down the road at night, when a deer runs out in front of your car.

You experience the emotion of fear and a physical response to the threat at the same time.

You feel panic at the possibility of hitting the deer and causing damage to the car or injury to yourself. At the same time, your heart starts beating much faster and you slam on the brakes to avoid the deer.

Meeting someone you like

You have a first date with someone you may like romantically.

You hear the knock on your door and immediately experience butterflies in your stomach as you feel excited and happy.

Seeing your child run out into the road

You’re spending some time in the park with your child. Suddenly, you see your little one run after a ball that’s heading in the direction of a nearby road.

You feel a sudden jolt of fear as your heart beats fast and you scream and run after your baby.

The James-Lange theory proposes that emotions result from a physical reaction and as a result are tied to physiological responses to stimuli. So, emotion cannot exist without a previous physiological reaction.

Here’s how the James-Lange theory would explain a real-world scenario, compared with the Cannon-Bard theory.

Go back to the example of the car and the deer.

In the James-Lange theory, the first reaction to seeing the animal is to slam on the brakes. This physical response (slamming the breaks) then causes the emotions tied to that physical response — in this case, fear.

The Cannon-Bard theory rejects the idea that fear comes from the act of slamming on the breaks. Instead, in this theory, the same stimulus (the deer in the road) triggers both an emotional response (fear) and a physical response (slamming the brakes) at the same time.

In short, the theories are competing points of view on the same responses and processes.

The Cannon-Bard theory has been challenged multiple times. One of the main criticisms it has received is that it gives too much importance to the thalamus when explaining emotions.

Even though research does show that the thalamus is involved in the experience of emotions, other brain regions not considered by the theory also play an important part.

According to a literature review published in 2014, one major flaw in the Cannon-Bard theory is that it doesn’t take into account that a person’s physical reactions can, in fact, influence emotional experiences. Multiple studies suggest this is possible.

Studies in the review have shown that asking someone to hold specific facial expressions can influence how that person feels. In other words, if you hold a “sad expression,” you may begin to feel down after a while, even if no stimulus has been presented.

Another theory, published in 1962, is known as the Schachter-Singer or two-factor theory of emotion. It takes elements of both the Cannon-Bard and the James-Lange theories. It states that physical reactions to stimuli occur before experiencing an emotion, but these reactions can be similar for different emotions.

According to the two-factor theory, you “will assign an emotion to a physiological change based on the available emotions in the social situation.” In other words, you experience a physical reaction first and then later assign an emotional value to it.

Return to the case of a deer running into the road. In the Schachter-Singer, you first experience a physical reaction: trembling, rapid heartbeat, and slamming on the brakes. Once you have a chance to process these reactions, you realize you feel fear.

The Schachter-Singer theory has also been criticized, since as early as 1967.

Current emotion theorists and researchers do not agree on assigning an order to emotional responses, but they generally accept there are three aspects involved in emotions, including:

  • the experiences, or stimuli
  • behavioral responses, or the expression of emotion
  • physiological responses, or the physical change that occurs

The Cannon-Bard theory of emotions states that you experience emotional and physical responses to stimuli independently but at the same time, and that the thalamus is the main actor in this process.

The theory has been widely refuted, since research has shown that other regions of the brain besides the thalamus are involved in the experience of emotions. Other studies have also shown that physical responses can influence how you feel, which would mean that experience and expression of emotions don’t always happen at the same time.