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The personal experience of pain produces a reliable effect on facial behavior in humans and in nonhuman mammals. Why should pain have a face? What is it for? I will attempt to head towards answering this question by invoking a theoretical framework: polyvagal theory (Porges, 2001, 2006).

1 Polyvagal Theory

According to polyvagal theory (Porges, 2001, 2006), evolution of neural control within the autonomic nervous system (ANS) has tracked three stages, each revealing a specific behavior, and a specific function:

In the first stage, the ancient unmyelinated visceral vagus nerve that enables digestion could respond to danger and pain only by reducing metabolic output and producing immobilization behaviors.

In the second stage, the sympathetic nervous system (SNS) made it possible to increase metabolic activity and inhibit the visceral vagus nerve, thus allowing fight/flight behaviors following perceived threat or pain.

The third stage, which is uniquely mammalian, involves a myelinated vagus that can rapidly control cardiac and bronchi output to enable spontaneous interaction (i.e., engagement or disengagement) with the environment. The interaction of the autonomic nervous system (ANS) with the hypothalamo-pituitary-adrenal (HPA) axis, nervous and immune systems change to maximize response to stressors such as nociception. During nociception, the ANS operates together with nervous, endocrine and immune systems to produce stress (Chapman et al. 2008; Porges, 2001, 2006). In terms of polyvagal theory, pain facial expression is a dynamic autonomic response caused by noxious signaling. In terms of polyvagal-type identity mechanistic theory pain facial expression is a type of behavior that is identical to a type of neurophysiological mechanism; namely, the phylogenetically recent brain-heart-face mechanism.

The expansion of cortex in the third stage increased innervation and neural control of the mammalian face: upper face innervation is bilateral and arises from the supplementary motor area (M2) and the rostral cingulate motor area (M3). Lower face innervation is contralateral and arises from primary motor cortex (M1), ventral lateral premotor cortex, and the caudal cingulate motor cortex (M4) (Morecraft et al. 2004). Human pain facial movements of the eyebrows and upper lip are type identical with negative emotional aspects of pain and activation of M1, M2, M3, whereas facial movements around the eyes are type identical with somatosensory aspects of pain, and activation of M2 and M3 (Kunz et al. 2011). Thus, evolution of cranial anatomy enabled a highly integrated facial representation of the multidimensional experience of pain.

2 Why Pain Should Have a Face

In clinical and experimental settings, the pain face is observed to rapidly appear following noxious stimulation, and diminish concurrent with cessation of the noxious stimulus, or when analgesics are administered (e.g., Craig & Patrick, 1985). The brain-heart-face mechanism is an integrated system with both a somatomotor part controlling the striated facial muscles and a visceromotor part controlling the heart through a myelinated vagus nerve (Porges, 2001, 2006). When the vagal tone to the cardiac pacemaker is high, the myelinated vagus acts as a brake or restraint limiting heart rate. Rapid inhibition and disinhibition of vagal tone to the heart supports the rapid mobilization of facial muscles and formation of the pain face concurrent with pain onset. In humans and nonhuman mammals, the main vagal inhibitory pathways in the myelinated vagus originate in the nucleus ambiguus.

The vagal brake supports the low-metabolic requirements involved in the rapidly appearing and disappearing pain face. Withdrawal of the vagal brake is strongly correlated with the rapid appearance of the pain face; reinstatement of the vagal brake is strongly correlated with the rapid diminishing of the pain face. These correlations are not unique to pain facial expression; similar relationships hold with regard to the vagal brake and the timing and duration of aversive, but non-noxious emotional facial expressions (e.g., Pu et al. 2010), and positive emotional facial expressions (e.g., Kok & Fredrickson, 2010).

In terms of the function of rapid pain face onset and offset, the vagal brake makes it possible for the individual in pain to quickly disengage from source of wounding and pain, concurrent with the rapid appearance or diminishing of pain facial expression, which may offer temporary access to additional metabolic resources to aid healing, recovery and self-soothing behaviors, with likely involvement from care givers.

Concerning aid from others, the vagal brake reliably maps onto specific interaction types observed in mammalian pain events. In pain events comprising the individual in pain and care givers, mammalian behavior is typed according to interpersonal communication through facial expressions, vocalizations, head and hand gestures (Hadjistavropoulos et al. 2011; Porges, 2001, 2006; Williams, 2002). A relevant feature is the rapid ‘switching’ of temporary engagement to temporary disengagement behaviors between the individual in pain and care givers. This interaction type may involve care givers speaking to the one in pain, and then quickly switching to listening; for the one in pain, looking into the face of the care giver, and then quickly switching to vocalizing (Craig et al. 2011; Hadjistavropoulos et al. 2011; Porges, 2001, 2006; Williams, 2002). The brain-heart-face mechanism thus allows the one in pain and the care giver to get the timing right. Some philosophers and neuroscientists claim that evolutionary neurobehavioral solutions to timing problems such as these are implicated in the origin of empathy and ultimately consciousness itself (Churchland, 2002; Cole, 1998; Engen & Singer, 2012; van Rysewyk, 2011).

However, if pain is severe or chronic and the vagal brake is withdrawn (or dysfunctional), the concurrency of increased pain facial expression, cardiac output, and other mobilization behaviors (i.e., increased SNS and HPA output), means that, if care giving is to succeed in promoting healing and recovery, the care giver’s vagal brake must be dynamically reinstated. By applying their own vagal brake, care givers may regulate their own visceral distress and thereby succeed in allocating valuable metabolic resources to communicate safety to the one in pain (and themselves) through calming facial and head behaviors, eye gaze, and prosodic vocalizations (i.e., increasing the vagal brake decreases SNS and HPA output). Since the vagal brake of the person in pain has been provisionally withdrawn, the care giver is effectively an integrated external brain-heart-face mechanism (cf. Tantam, 2009, the ‘interbrain’).

Thus, the pain facial muscles function as neural timekeepers detecting and expressing features of safety and danger that cue the one in pain to quickly disengage from the source of wounding and pain, simultaneous with the rapid appearance or attenuation of pain facial activity, and also cue others who can help.


Chapman, C. R., Tuckett, R. P., & Song, C. W. (2008). Pain and stress in a systems perspective: reciprocal neural, endocrine, and immune interactions. Journal of Pain, 9(2), 122-145.

Churchland, P. S. (1989). Neurophilosophy: Toward a Unified Science of the Mind-Brain. Cambridge, Mass.: MIT Press.

Cole, J. (1998) About face. Cambridge, Mass.: The MIT Press.

Craig, K. D., & Patrick, C. J. (1985). Facial expression during induced pain. Journal of Personality and Social Psychology, 48(4), 1080-1091.

Craig, K. D., Prkachin, K. M., & Grunau, R. E. (2011). .The facial expression of pain. In D. C. Turk, & R. Melzack, Handbook of Pain Assessment, 2nd Edition (pp. 117-133). New York: The Guilford Press.

Engen, H. G., & Singer, T. (2012). Empathy circuits. Current Opinion in Neurobiology, 23, 1-8.

Hadjistavropoulos, T., Craig, K. D., Duck, S., Cano, A., Goubert, L., Jackson, P. L., Mogil, J. S., Rainville, P., Sullivan, M. J. L., de C. Williams, Amanda C., Vervoort, T., & Fitzgerald, T. D. (2011). A biopsychosocial formulation of pain communication. Psychological Bulletin, 137(6), 910-939.

Kok, B. E., & Fredrickson, B. L. (2010). Upward spirals of the heart: Autonomic flexibility, as indexed by vagal tone, reciprocally and prospectively predicts positive emotions and social connectedness. Biological Psychology, 85(3), 432-436.

Kunz, M., Lautenbacher, S., LeBlanc, N., & Rainville, P. (2011). Are both the sensory and the affective dimensions of pain encoded in the face? Pain, 153(2), 350-358.

Morecraft, R. J., Stilwell-Morecraft, K. S., & Rossing, W. R. (2004). The Motor Cortex and Facial Expression: New Insights From Neuroscience. The Neurologist, 10(5), 235-249.

Porges, S. W. (2001). The polyvagal theory: phylogenetic substrates of a social nervous system. International Journal of Psychophysiology, 42(2), 123-146.

Porges, S. W. (2006). Emotion: An Evolutionary By‐Product of the Neural Regulation of the Autonomic Nervous System. Annals of the New York Academy of Sciences, 807(1), 62-77.

Pu, J., Schmeichel, B. J., & Demaree, H. A. (2010). Cardiac vagal control predicts spontaneous regulation of negative emotional expression and subsequent cognitive performance. Biological Psychology, 84(3), 531-540.

van Rysewyk, S. (2011). Beyond faces: The relevance of Moebius Syndrome to emotion recognition and empathy. In: A. Freitas-Magalhães (Ed.), ‘Emotional Expression: The Brain and the Face’ (V. III, Second Series), University of Fernando Pessoa Press, Oporto: pp. 75-97.

Williams, A. C. D. C. (2002). Facial expression of pain: an evolutionary account. Behavioral and Brain Sciences, 25(4), 439-455.


Call for Chapters: Machine Medical Ethics, Edited Collection

You are warmly invited to submit your research chapter for possible inclusion in an edited collection entitled Machine Medical Ethics. Target publication date: 2014.

The new field of Artificial Intelligence called Machine Ethics is concerned with ensuring that the behaviour of machines towards human users and other machines is ethical. This unique edited collection aims to provide an interdisciplinary platform for researchers in this field to present new research and developments in Machine Medical Ethics. Areas of interest for this edited collection include, but are not limited to, the following topics:

Foundational Concepts

What is medical ethics?

What is machine medical ethics?

What are the consequences of creating or not creating ethical medical machines?

Can medical machines be autonomous?

Ought medical machines to operate autonomously, or under (complete or partial) human physician control?

Theories of Machine Medical Ethics

What theories of machine medical ethics are most theoretically plausible and most empirically supported?

Ought machine medical ethics be rule-based (top-down), case- based (bottom-up), or a hybrid view of both top-down and bottom-up?

Is an interdisciplinary approach suited to designing a machine medical ethical theory? (e.g., collaboration between philosophy, psychology, AI, computational neuroscience…)

Medical Machine Training

What does ethical training for medical machines consist in: ethical principles, ethical theories, or ethical skills? Is a hybrid approach best?

What training regimes currently tested and/or used are most successful?

Can ethically trained medical machines become unethical?

Can a medical machine learn empathy (caring) and skills relevant to the patient-physician relationship?

Can a medical machine learn to give an apology for a medical error?

Ought medical machines to be trained to detect and respond to patient embarrassment and/or issues of patient privacy? What social norms are relevant for training?

Ought medical machines to be trained to show sensitivity to gender, cultural and age-differences?

Ought machines to teach medicine and medical ethics to human medical students?

Patient-Machine-Physician Relationship

What role ought imitation or mimicry to play in the patient-machine-physician relationship?

What role ought empathy or caring to play in the patient-machine-physician relationship?

What skills are necessary to maintain a good patient-machine-physician relationship?

Ought medical machines be able to detect patient fakery and malingering?

Under what conditions ought medical machines to operate with a nurse?

In what circumstances should a machine physician consult with human or other machine physicians regarding patient assessment or diagnosis?

Medical Machine Physical Appearance

Is there a correlation between physical appearance and physician trustworthiness?

Ought medical machines to appear human or non-human?

Is a highly plastic human-like face essential to medical machines? Or, is a static face sufficient?

What specific morphological facial features ought medical machines to have?

Ought medical machines to be gendered or androgynous?

Ought medical machines to possess a human-like body with mobile limbs?

What vocal characteristics ought medical machines to have?

As a new field, the target audiences are expected to be from the scientists, researchers, and practitioners working in the field of machine ethics and medical ethics. The target audience will also include various stakeholders, like academics, research institutes, and individuals interested in this field, and the huge audience in the public sector comprising health service providers, government agencies, ministries, education institutions, social service providers and other types of government, commercial and not-for-profit agencies.

Please indicate your intention to submit your full paper by email to the editor who emails you with the title of the paper, authors, and abstract. The full manuscript, as PDF file, should be emailed to that same editor by the deadline indicated below. Authoring guidelines will be mailed to you after we receive your letter of intent.

Please feel free to contact the editors, Simon van Rysewyk or Dr. Matthijs Pontier, if you have any questions or concerns. Many thanks!


Intent to Submit: June 10, 2013

Full Version: October 20, 2013

Decision Date: November 10, 2013

Final Version: December 31, 2013


Simon van Rysewyk

School of Humanities
University of Tasmania
Private Bag 41
Tasmania 7001


Dr. Matthijs Pontier

Post-Doctoral Researcher
The Centre for Advanced Media Research (CAMeRA)
Vrije Universiteit Amsterdam
Buitenveldertselaan 3
1081 HV Amsterdam
The Netherlands


My #SciFund video is finally complete!

Quite a mission to do (first time), but I am happy with the finished product.

Click on the image:









Here is a map showing the global distribution of participating scientists in Round 1 (2011) and Round 2 (May, 2012) of the #SciFund Challenge:

SciFunders Standing Tall and Talented

Come tomorrow, my #SciFund project will go online with other projects in Round 2 of the #SciFund Challenge!
What is the #SciFund Challenge?
#SciFund Challenge is about raising funds for important and interesting science projects.
It’s called crowdfunding.
In 2011, Round 1 of the #SciFund Challenge raised over US$76,000 for science projects!
The participating scientists included students, professors and independent researchers.
How does it work?
Each participating scientist creates a project, and a fundraising target.
Next, each scientist promotes their project online through social media, personal blogs,
YouTube, #Scifund blogs and #Scifund website, from May 1 to May 31, 2012.
A big part of a crowdfunding campaign is a 2-3 minute video advertising the project.
I’ll wrap-up my video tomorrow, and post it on RocketHub (the online host of #SciFund Round 2).
Next, I’ll invite you all to have a look at my excellent project page on RocketHub.
Then, you can decide whether I have convinced you or not!
What is my #SciFund project?
It is my PhD project: ‘The face of pain’. Intrigued yet?
Some of the questions I am looking at are:
What differentiates pain faces from emotion faces?
What facial features communicate the most information in a pain face?
How do observers fixate on, react to, and interpret faces of pain?
These aren’t merely interesting questions.
There is potential for direct clinical application.
How? The more clearly we define the attributes that make pain a unique expression,
the better equipped we are to assess and manage pain in patients.
This is especially critical in patients who lack verbal expressions or language
(e.g., patients with verbal disorders, dementia, autism, neonates, infants).
Clinicians rely heavily on non-verbal expressions of pain (e.g., facial expression) in such cases.
What is my fundraising target?
My target is US$1000. 
This target is very achievable given a bit of work on my part during May,
and your outstanding generosity and vision!
This target will fund costs related to conducting my experiments online (it ain’t cheap!).
Oh, and did I mention there are rewards for donators?
I’m not kidding around.
I’ll reveal my rewards when my project is online tomorrow!
Now, if you don’t wish to support my project, that’s completely OK.
But, I do ask of you one small thing: spread the word about my #SciFund project 
through your social network.
How is that? 
Muchas gracias, mi buen amigo!
What happens next?
I will post the link to my project-page on Rocket Hub on this blog!

John Donne was partly right: A person is an island. But – every island is surrounded by water.

I am half myself, half you.

I am surrounded by your facial expressions. I adopt them as my own.

I cannot predict your every thought and action for the simple reason that most of my own thoughts and actions are completely spontaneous.

I cannot predict what I will do in most instances. I cannot know myself, so I cannot know you. True enough? We are both in the dark, it seems.

That sounds a bit bleak.

Is there any good news?

Yes: A person is not a vacuum. Human thought and action is shared. Shared, copied, modified, suppressed, distilled – we live in each other’s facial expressions.

A report is here.

patient-before-surgery.jpg (384×512)

Patient before surgery

patient-after-surgery.jpg (408×512)

Patient after surgery

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