When someone is angry, their respiration, heart rate, and sweating increase. The same responses are also seen when someone is afraid. Walter Cannon suggested that such findings brought which theory into question?

The James-Lange theory of emotion.

Explanation:

According to the James-Lange theory, emotion is equivalent to the array of physiological arousal resulting due to external incidents. The two scientists indicated that for someone to feel emotion, he or she must first encounter with bodily responses like increased heart rate, increased respiration, or sweaty hands.

Once this physiological reaction is determined, then the individual can suggest that he or she is feeling the emotions. This is in contrast to the general common-sense way of thinking regarding the cause and effect association between the experience of emotion and its expression.