Two articles provide a connection between physiological control over heart rate and the sympathetic/parasympathetic nervous system (vagal tone), empathic traits (empathic accuracy and empathic behaviors), and social power.
First source is entitled, “Social Power Facilitates the Effect of Prosocial Orientation on Empathic Accuracy” (ref: Link to PDF). Briefly, they found that prosocial orientation (measured by respiratory sinus arrhythmia, or one’s ability to change heart rate with breathing) improves empathic accuracy (ability to accurately judge the emotions of a stranger) when the individual is (or perceives to be) of high power. They found that individuals they induced to feel powerful were more capable of gauging a stranger’s emotional state.
The second source is entitled, “Roots and Benefits of Costly Giving: Children Who Are More Altruistic Have Greater Autonomic Flexibility and Less Family Wealth” (ref:Link to PDF). The research indicates that children who forgo self-gain to help other people tend to have greater vagal flexibility and higher subsequent vagal tone compared to children who do not, and this effect is measured early on in child development. They define altruism as “costly helping” and posit that altruism is one of the harder prosocial behaviors to learn. There is a field of study (called polyvagal theory) dedicated to studying how our biology affects our behaviors and perceptions. Polyvagal theory “posits that prosociality is supported by physiological states that foster calm social engagement and inhibit defensive responding (i.e., fight-or-flight behaviors).
More to come.