Final answer:
The Cannon-Bard theory states that physical arousal and cognitive appraisal of an emotion-provoking stimulus happen simultaneously.
Step-by-step explanation:
The theory of emotion that proposes that physical arousal and cognitive appraisal of the stimulus happen simultaneously is known as the Cannon-Bard theory. This theory suggests that when we encounter a stimulus, such as a venomous snake, we feel fear and our body activates the fight-or-flight response at the same time. These two responses occur independently yet simultaneously, challenging earlier theories like the James-Lange theory, which claimed that emotional experiences follow physiological arousal. In contrast, the Schachter-Singer two-factor theory, another important concept in emotion research, postulates that our physiological arousal needs to be interpreted in context and labeled to result in the specific emotional experience.