The neural response to emotional robots

When it comes to robotics, Japan is way ahead of the rest of the world. Reality is quickly catching up with science-fiction as robots are being used and developed for increasingly complex behaviours. There are now Japanese robots that function as security guards, trainers for professional skills, and even pets and social companions.

Robots are taking over roles that were once thought to make humans unique. An archetypal example of this is the use of robots for cognitive therapy. Robots are also being used for social assistance and personal care of the elderly. But how does robot social support fare against human support? Is it really possible to empathize with and emotionally respond to a robot while simultaneously knowing that it is just a robot?

Researchers from – you guessed it – Japan, recently collaborated with an international team to investigate how our brains respond to robots expressing human emotions. A humanoid robot, called WE4-RII, was specially designed to make facial expressions for emotions such as disgust, anger and joy. Study participants had their brains scanned with fMRI as they watched either WE4-RII expressing emotions or a human expressing the same emotions. The subjects were asked to attend to either the way the robot/human face was moving or to the emotion being depicted.

When subjects attended to emotions, it was found that brain activity in areas involved in processing emotions (such as the left anterior insula for the perception of disgust) was reduced for robot compared to human stimuli. However, when participants attended to emotions rather than motions, it was also found that brain activity was increased in the ‘motor resonance’ (i.e., the controversial mirror neuron) circuit.

The experimenters suggested this means we don’t emotionally resonate with robots as well as we do with humans, but we relate to robot facial motions better when we attend to their emotions.

The latter claim may seem counterintuitive, but it matches behavioural experiments that suggest a ‘motor interference effect’ for robotic movements. That is, when we attend to robotic movements, we don’t think of these movements as something that we do when we move, so we don’t resonate with them. But when we stop attending to the movements, we don’t notice the robotic nature of these movements anymore, and we therefore imitate them to a greater degree. I wonder if this would be much different for people who are really good at dancing the robot.

Still the experiment doesn’t demonstrate that we can’t emotionally relate to robots to the same degree as to humans. The robot used was clearly mechanical compared to the human actors. This means that subjects knew the robot was a robot. If you can’t tell whether a face is robot or human, however, it would be expected that the brain would respond in the same way.

An interesting follow-up study could address this problem by using more human-looking robots and including two groups of subjects: those who are aware of the robots and those who are not. Then we’d be able to see how previous knowledge affects our innate reactions to emotional facial expressions.

And another central question remains. Now that robots are taking over traditional human roles, when will we start scanning their ‘brains’ and investigating whether they can empathize with us? I won’t be visiting any hot-shot robot psychotherapist until we have data that shows they care.



Thierry Chaminade1,2*, Massimiliano Zecca3,4,5, Sarah-Jayne Blakemore6, Atsuo Takanishi, Chris D.Frith1, Silvestro Micera, Paolo Dario, Giacomo Rizzolatti, Vittorio Gallese11, & Maria Alessandra Umilta (2010). Brain Response to a Humanoid Robot in Areas Implicated in the Perception of Human Emotional Gestures PLoS ONE

The empathetic vegetarian brain

It is often the case that meatless lifestyles are chosen for ethical reasons related to valuing animal rights. As a consequence of their food choices, vegetarians and vegans are often accused of and taunted for loving animals more than people. But do most vegetarians care less for fellow humans than animals, care for humans and animals equally, or care more for humans than animals but still care more for animals than omnivores do?

A study published yesterday in PLoS ONE has attempted to parse out differences among omnivores, vegetarians and vegans in brain responses to human and animal suffering. The three groups were first given the Empathy quotient questionnaire, and it was determined that vegans and vegetarians scored significantly higher in empathy than omnivores. Next, the subjects had their brains scanned with fMRI as they viewed images of human suffering, animal suffering and “neutral” natural landscapes. Many differences were found among the brains of those with different feedings habits.

Firstly, vegetarians and vegans had higher engagement than omnivores of “empathy related areas,” such as the anterior cingulate cortex (ACC) and left inferior frontal gyrus (IFG), while observing both human and animal suffering. This seems to suggest that there is a neural basis for those with meatless lifestyles having greater empathy for all living beings.

However, when viewing animal suffering but not human suffering, meat-free subjects recruited additional empathy related areas in prefrontal and visual areas and reduced their right amygdala activity. This may be interpreted as evidence that vegetarians and vegans care more about the emotions of animals than those of humans. It is important to consider how the study was conducted, though, before reaching such a conclusion.

The authors themselves note a couple of weaknesses in their design. The subjects’ brain activities while they viewed human or animal suffering were compared to the baseline/control condition of “neutral” scenes that did not include living beings, faces, or suffering of any kind, which are all factors that should have been considered. The subjects were also simply asked to look at the images of the different conditions without being asked about their thoughts or feelings, so it is impossible to confidently attribute their brain responses to specific emotions. But even if the demonstrated brain activity represented empathy, there is also the possibility that the subjects were desensitized to images of human suffering that appear daily on the news. Desensitization to an image does not necessarily reflect empathetic feelings toward fellow humans. So a claim that vegetarians/vegans love animals more than humans because they have more empathetic neural activity while viewing suffering animals than suffering humans is unsubstantiated at this point.

Another major finding in this study was differences in neural representations of cognitive empathy between vegetarians and vegans. All of these subjects had chosen not to eat meat for ethical reasons, but the authors suggest that these differences in vegan and vegetarian brain responses indicate that the groups experience empathy for suffering differently, possibly due to differences in reasons for their diet choices. Again, these results should be taken as preliminary because of weaknesses in the study’s design.

Overall the study is interesting, but it remains to be seen whether this will spark further research that will ultimately demonstrate findings significant enough to affect public policy and animal cruelty regulations. For now, we have a bit of a clearer picture of the brain’s representation of empathy and a lot of extra material for the never-ending ethical debate over man’s right to meat.



Filippi M, Riccitelli G, Falini A, Di Salle F, Vuilleumier P, Comi G, & Rocca MA (2010). The Brain Functional Networks Associated to Human and Animal Suffering Differ among Omnivores, Vegetarians and Vegans PLoS ONE

Empathy for pain in doctors versus synesthetes

A common warning given to students interested in a career in medicine is “you better have a tough stomach.” Luckily for physician-wannabes who tense up at the sight of blood, a new study published in NeuroImage suggests that it may be possible to change your brain’s response to watching pain being inflicted on others. The findings are nicely summarized at the BPS Research Digest blog:

Decety's team used electroencephalography (EEG) to monitor the electrical activity arising from the brains of 15 doctors and 15 controls while they looked at dozens of static pictures of people being pricked in various body parts by a needle or prodded by a cotton bud.

When a person looks at someone else in pain, their EEG response typically shows two distinct characteristics: a frontal component after 110ms, which is thought to reflect an automatic burst of empathy, and a more central, parietal component after about 350ms, which reflects a conscious evaluation of what's been seen.

As expected, the control participants showed an enhanced early and later phase EEG response to the needle pictures compared with the cotton bud pictures. The doctors, by contrast, showed no difference in brain response to the two categories of picture.

This means that doctors are essentially the opposite of people who experience synesthesia for pain, a condition I previously wrote about. Synesthesia for pain, the physical experience of pain induced by simply viewing pain in another, has mainly been identified in rare ‘phantom limb’ patients who have had an amputation but still experience sensations in the absent limb. If you can recall, certain areas of the brain are active when pain is felt: some areas involving emotion/affective processing, some areas involving cognition/evaluation, and other areas involving the actual sensation of pain. It is hypothesized that pain synesthetes have overly-sensitive responses to viewing pain in brain regions that are responsible for conscious pain perception.

In contrast, Decety’s new study suggests that doctors have under-active responses in the whole pain matrix. If this under-active response can be acquired by training (e.g. assisting surgeries in medical school), perhaps pain synesthetes could make their empathetic pain experiences go away by repeatedly viewing needles being pressed into others. However, this might not be the best treatment approach as it would probably be exceptionally painful for the synesthete.

Pain synesthesia is acquired (usually after injury/amputation), unlike most other identified forms of synesthesia in which people are supposedly born experiencing numbers as colours or sounds as tastes. Perhaps this means pain synesthesia can be cured as well.

Decety J, Yang CY, & Cheng Y (2010). Physicians down-regulate their pain empathy response: an event-related brain potential study. NeuroImage, 50 (4), 1676-82 PMID: 20080194

Fitzgibbon BM, Giummarra MJ, Georgiou-Karistianis N, Enticott PG, & Bradshaw JL (2010). Shared pain: from empathy to synaesthesia. Neuroscience and biobehavioral reviews, 34 (4), 500-12 PMID: 19857517

Synesthesia of empathy for pain

Synesthesia, the confusion of the senses, has fascinated artists and writers for centuries. However, the first medical description of a synesthete, who experienced “coloured hearing,” was not until 1812.

Now 61 different types of synesthesia have been identified, and new forms continue to regularly pop up in the scientific literature. The most common type is grapheme-colour synesthesia, in which an affected individual experiences letters and numbers as shaded or tinged with colour. There are also such things as “flavour-colour,” “sound-touch,” and “vision-temperature” synesthetes.

Interestingly, many of the more recently identified synesthesias involve emotion, a characteristic that has not traditionally been thought of as a primary “sense” but can be intimately linked to the senses. An example is synesthesia for pain, a condition in which the synesthete has so much empathy for the physical pain in others that the pain is actually experienced when it is observed. This variety of synesthesia was recently reviewed in a paper by Bernadette M. Fitzgibbon and colleagues that describes possible cognitive and neural mechanisms underlying the phenomenon.

Synesthesia for pain has mainly been found in rare phantom limb patients who have had an amputation but still experience sensations in the absent limb. This quality differentiates synesthesia for pain from many other forms of developmental synesthesia in that synesthesia for pain is acquired by experience. Although most of us (hopefully all of us?) feel empathetic towards those suffering from pain, it is thought that some phantom limb patients experience ‘uber-empathy’ for pain due to rewiring and reshaping of their brains.

The neural system that Fitzgibbon’s group mainly discuss as a possible underlying mechanism is of course our great unified theory of neuroscience: the mirror neuron system. Neuroimaging studies of non-synesthetes reveal that certain areas of the brain are active when pain is felt: some areas involving emotion/affective processing, some areas involving cognition/evaluation, and other areas involving the actual sensation of pain. When non-synesthetes observe pain being inflicted on another, the only activated component of the pain matrix is the emotional one. This finding has been interpreted as evidence for a mirror system of empathy (although this is hotly debated in the literature).

So the non-synesthetes feel bad for those experiencing pain but they don’t actual feel that pain (validating the claim “you’ll never understand my pain!!”).

Fitzgibbon’s group hypothesize that pain synesthetes have a “disinihibited” mirror empathy system, such that observation of pain elicits activity in all components of the pain matrix, including the areas involving the sensation of pain. This has not yet been tested, but neuroimaging studies could provide insight to the understanding of synesthesia for pain and possible treatments for this surely gruelling condition (imagine not being able to watch Scarface without feeling as though you are being dismembered by a chainsaw).

Interestingly – although this is pure speculation - further study of non-synesthetes could potentially help us understand synesthesia for pain. We all know people who cringe or feel tingly at the sight of blood. I know that I sometimes get goosebumps when viewing gory scenes in movies. Is this a less severe form of synesthesia for pain? Can these reactions be reduced with certain experiences, such as repeated exposure? Or with brain-altering interventions such as rTMS?

The synesthete may be viewed as abnormal, but perhaps we underestimate the interrelatedness of the senses that exists in us all.

References:

Fitzgibbon BM, Giummarra MJ, Georgiou-Karistianis N, Enticott PG, & Bradshaw JL (2010). Shared pain: from empathy to synaesthesia. Neuroscience and biobehavioral reviews, 34 (4), 500-12 PMID: 19857517