According to wikipedia :
In humans, posture can provide a significant amount of important information on nonverbal communication and emotional cues. Psychological studies have shown the effects of body posture on emotions. This research can be traced back to Charles Darwin when he studied emotion and movement in humans and animals. Currently, many studies have shown that certain patterns of body movements are indicative of specific emotions. Researchers studied sign language and found that even non-sign language users can determine emotions from only hand movements. Another example is the fact that anger is characterized by forward whole body movement. The theories that guide research in this field are the self-validation or perception theory and the embodied emotion theory.
- Self-Validation theory is when a participant’s posture has a significant affect on his or her self-evaluation of their emotions. An example of this is an experiment where participants had to think and then write positive qualities of themselves in a confident or doubtful posture. Participants then had to self-evaluate on how good of a job candidate, interviewee, performer, and how satisfied they would be as an employee. Mood and confidence level were also measured. Results from this study proved in favor of the self-validation theory. Participants’ attitudes in the confident but not doubtful posture, significantly affected their self-reported attitudes. A similar study showed that participants who were placed in a hunched posture reported were more likely to feel stressed compared to participants who assumed a relaxed position.
Embodied Emotion theory is the idea that mental events can be represented by states of the body. In a study showing embodied emotion, participants were primed with concepts of pride and disappointment by a word generation task. Researchers hypothesized there would be an observable change in participants’ posture based on the word they were primed with. This hypothesis was confirmed for the disappointment prime because participants were more likely to decrease in their vertical height or show slumping behavior.