In 1872 Darwin acknowledged the dynamic neural relationship between the heart and the brain and that when the heart is affected it reacts on the brain; and the state of the brain again reacts through the vagus nerve on the heart; so that under any excitement there will be mutual action and reaction between these two most important organs of the body.
Although Darwin acknowledged the bi-directional communication between the heart and the brain, subsequent formal description of the autonomic nervous system minimized the importance of central regulatory structures and afferent nervous system. Medical and physiological research tended to focus on the peripheral motor nerves of the autonomic nervous system, with a conceptual emphasis on the paired antagonism between sympathetic and parasympathetic efferent pathways on the target visceral organs. This focus minimized interest in both afferent pathways and the brainstem areas that regulate specific efferent pathways.
The brain has long enjoyed a privileged status as psychology’s favourite body organ. This is not surprising given that the brain instantiates virtually all mental operations, from understanding language, to learning that fire is dangerous, to categorizing fruits and vegetables, to predicting the future.
Arguing for the importance of the brain in psychology is like arguing for the importance of money in economics.
Psychology’s recognition of the body’s influence on the mind coincides with a recent focus on the role of the heart in social psychology. It turns out that the heart is not only critical for survival, but also for how people relate to one another. In particular, heart rate variability (HRV) plays a key role in social behaviours ranging from decision-making, regulating one’s emotions, coping with stress and even academic engagement.
Decreased HRV appears to be related to depression and autism and may be linked to thinking about information purposely. Increased HRV, on the other hand, is associated with greater social skills such as recognising other people’s emotions and helps people cope with socially stressful situations, such as giving a public presentation. This diverse array of findings reflects a growing interest across clinical psychology, neuroscience, social psychology, and developmental psychology in studying the role of the heart in social life.
A key moment for the field came in 1995, when Stephen Porges, currently a professor of psychiatry at the University of Illinois at Chicago, put forth the Polyvagal theory that emphasised the role of the heart in social behaviour. This theory states that the vagus nerve, a nerve found only in mammals, provides input to the heart to guide behaviour as complex as forming relationships with other people as well as disengaging from others. A distinguishing feature of the Polyvagal theory is that it places importance not on heart rate as such, but rather on the variability of the heart rate, previously thought to be an uninteresting variable or simple noise.
Since 1995, a broad spectrum of research emerged in support of Polyvagal theory and has demonstrated the importance of the heart in social functioning.
