The Cannon-Bard theory of emotion proposes that an emotion-arousing stimulus simultaneously triggers the physiological response and the subjective experience of emotion. The two occur together; neither causes the other.

Walter Cannon and Philip Bard developed the view in the 1920s as a challenge to the earlier James-Lange theory, which held that we feel afraid because we run. Cannon argued that the same bodily changes occur in different emotions and that the changes are often too slow to account for the rapidity of emotional feeling. Instead, he located the key processes in the thalamus, which he believed sent simultaneous signals to the cortex (producing the felt emotion) and to the autonomic nervous system (producing the bodily response).

Later research has refined the anatomy—the hypothalamus and limbic structures play larger roles than Cannon supposed—yet the central claim of simultaneous generation remains influential. Modern theories often incorporate elements of both Cannon-Bard and James-Lange, recognizing that feedback from the body can color and intensify emotion even if it is not the sole cause.

According to Cannon-Bard, when you meet a bear in the woods, the racing heart and the feeling of fear arise at the same moment from the same central process.