Physical Mechanisms of Emotions Evoked by Postural Feedback.

Adopting physical expressions of emotion has been shown to have feedback effects on individuals' mood and behavior. For example, adopting the expansive and contractive body language of dominance and submission can affect individuals' feelings of power. However, the effects can be subtle and variable; we suggest that this may be due to inter-individual variability in the physical expression of the experimental posture, including both the magnitude of the posture adopted and the specific muscles used to adopt it. Here, we employed a postural feedback (i.e., "power posing") paradigm and recorded quantitative measures of body position algorithmically derived from video recordings (N = 101). We demonstrate for the first time that variation in neck flexion mediates the effects of posture on mood. We also investigated several other variables which, based on previous work, could additionally mediate or moderate the postural feedback effects, finding that subjective difficulty also mediates posture effects independently of neck flexion, with effects moderated by body awareness. Finally, we investigated the muscular processes underlying neck flexion in the posture using electromyography, demonstrating that the neck flexion which mediates mood effects is associated with sternocleidomastoid muscle activity. The present work carries implications for our understanding of the adaptive benefits of expansive and contractive postures, and provides important methodological insights into the paradigms typically used for research on postural feedback.