Simulation theory of empathy

Simulation theory is based in philosophy of mind, a branch of philosophy that studies the nature of the mind and its relationship to the brain, especially the work of Alvin Goldman and Robert Gordon. The discovery of mirror neurons in macaque monkeys provides a physiological mechanism to explain the common coding between perception and action (see Wolfgang Prinz){{cite journal|author1=di Pellegrino, G.|author2=Fadiga, L.|author3=Fogassi, L.|author4=Gallese, V.|author5=Rizzolatti, G.|name-list-style=amp|year=1992|title=Understanding motor events - A neurophysiological study|journal=Experimental Brain Research|volume=91|issue=1|pages=176–180|url=https://www.uni-muenster.de/imperia/md/content/psyifp/aeechterhoff/wintersemester2011-12/vorlesungkommperskonflikt/dipellegrino_etal_understmotorevents_ebr1992.pdf|doi=10.1007/BF00230027|pmid=1301372|s2cid=206772150}} and the hypothesis of a similar mirror neuron system in the human brain.{{cite journal|author1=Preston, S.D.|author2=de Wall, F.B.M.|name-list-style=amp|year=2002|title=Empathy: its ultimate and proximate bases|journal= Behavioral and Brain Sciences|volume=25|issue=1|pages=1–20; discussion 20–71|pmid=12625087|url=https://greatergood.berkeley.edu/images/uploads/Preston_dewaal2002.pdf|doi=10.1017/S0140525X02000018|citeseerx=10.1.1.554.2794}}

• {{cite journal|author1=Iacoboni, M.|author2=Woods, R. P.|author3=Brass, M.|author4link=Harold Bekkering|author4=Bekkering, H.|author5=Mazziotta, J. C.|author6=Rizzolatti, G.|name-list-style=amp|year=1999|title=Cortical mechanisms of human imitation|journal=Science|volume=286|issue=5449|pages=2526–2528|pmid=10617472|doi=10.1126/science.286.5449.2526|citeseerx=10.1.1.555.8075}}

Since the discovery of the mirror neuron system, many studies have been carried out to examine the role of this system in action understanding, emotion, and other social functions.

Mirror neurons are activated both when actions are executed and when actions are observed. This function of mirror neurons may explain how people recognize and understand the states of others: they mirror the observed action in the brain as if they conducted the observed action.{{cite journal|author1=Gallese, V.|author2=Keysers, C.|author3=Rizzolatti, G.|name-list-style=amp|year=2004|title=A unifying view of the basis of social cognition|journal=Trends in Cognitive Sciences|volume=8|issue=9|pages=396–403|doi=10.1016/j.tics.2004.07.002|pmid=15350240|s2cid=11129793}}

Two sets of evidence suggest that mirror neurons in the monkey have a role in action understanding. First, the activation of mirror neurons requires biological effectors such as the hand or mouth. Mirror neurons do not respond to actions undertaken by tools like pliers.{{cite journal|author1=Gallese, V.|author2=Fadiga, L.|author3=Fogassi, L.|author4=Rizzolatti, G.|name-list-style=amp|year=1996|title=Action recognition in the premotor cortex|journal= Brain|volume=119|issue=Pt 2|pages=593–609|doi=10.1093/brain/119.2.593|pmid=8800951|url=https://oup.silverchair-cdn.com/oup/backfile/Content_public/Journal/brain/119/2/10.1093/brain/119.2.593/2/119-2-593.pdf?Expires=1503967362&Signature=Os76kN4jb5~VnamS8nnnGygb1NgkSFeJOnUd31~p4yGzlf1Wq1Rcy2qY5PG7Ge6cY8c~y6rACSooAufP7LVv3jJ6wbQtPs~EeAsD4ipU1X3BaZPivdKn71LmaJzH-16an64ebBEND3aeKOgbWfoflI~O4nmNbwhm-LJlbspzmiJqb4GdnxxPYJ00cDkoyLiXpElbqPvkbX7-v8mJQG6Jeyh9BWjvofIJo1sRmBgJ6FEJ0fINEXVAzhuxod8ggtUbJNNS9x29N1Yc2sGigsLL-kCY~i~9AOFH8mR6kayfNA27GEKkp1dm2lxxfJSNTbuyxSGkbXBJZs6D9AyBIhsRxg__&Key-Pair-Id=APKAIUCZBIA4LVPAVW3Q|doi-access=free}} Mirror neurons respond to neither the sight of an object alone nor to an action without an object (intransitive action). Umilta and colleagues demonstrated that a subset of mirror neurons fired in the observer when a final critical part of the action was not visible to that observer.{{cite journal|author1=Umilta, M. A.|author2=Kohler, E.|author3=Gallese, V.|author4=Fogassi, L.|author5=Fadiga, L.|author6=Keysers, C.|display-authors=etal|year=2001|title=I know what you are doing: A neurophysiological study|journal=Neuron|volume=31|issue=1|pages=155–165|pmid=11498058|doi=10.1016/S0896-6273(01)00337-3|doi-access=free}} The experimenter showed his hand moving toward a cube and grasping it, and later showed the same action without showing the final grasping of the cube (the cube was behind an occluder). Mirror neurons fired in both scenarios. However mirror neurons did not fire when the observer knew that there was not a cube behind the occluder.

Second, responses of mirror neurons to the same action are different depending on context of the action. A single cell recording experiment with monkeys demonstrated the different level of activation of mouth mirror neurons when monkey observed mouth movement depending on context (ingestive actions such as sucking juice vs. communicative actions such as lip-smacking or tongue protrusions).{{cite journal|author1=Ferrari, P. F.|author2=Gallese, V.|author3=Rizzolatti, G.|author4=Fogassi, L.|name-list-style=amp|year=2003|title=Mirror neurons responding to the observation of ingestive and communicative mouth actions in the monkey ventral premotor cortex|journal=European Journal of Neuroscience|volume=17|issue=8|pages=1703–1714|pmid=12752388|doi=10.1046/j.1460-9568.2003.02601.x|citeseerx=10.1.1.177.2287|s2cid=1915143}} An fMRI study also showed that mirror neurons respond to the action of grasping a cup differently depending on context (to drink a cup of coffee vs. to clean a table on which a cup was placed).{{cite journal|author1=Iacoboni, M.|author2=Molnar-Szakacs, I.|author3=Gallese, V.|author4=Buccino, G.|author5=Mazziotta, J. C.|author6=Rizzolatti, G.|name-list-style=amp|year=2005|title=Grasping the intentions of others with one's own mirror neuron system|journal=PLOS Biology|volume=3|issue=3|pages=529–535|pmid=15736981|pmc=1044835|doi=10.1371/journal.pbio.0030079 |doi-access=free }}

Since mirror neurons fire both for someone watching an action and someone completing an action, they may only predict actions, not beliefs or desires.

Shared neural representation for a motor behavior and its observation has been extended into the domains of feelings and emotions. Not only observations of movements but also those of facial expressions activate the same brain regions that are activated by direct experiences. In an fMRI study, the same brain regions activated when people imitated and observed emotional facial expressions such as happy, sad, angry, surprise, disgust, and afraid.{{cite journal|author1=Carr, L.|author2=Iacoboni, M.|author3=Dubeau, M. C.|author4=Mazziotta, J. C.|author5=Lenzi, G. L.|name-list-style=amp|year=2003|title=Neural mechanisms of empathy in humans: A relay from neural systems for imitation to limbic areas|journal=Proceedings of the National Academy of Sciences of the United States of America|volume=100|issue=9|pages=5497–5502|pmid=12682281|pmc=154373|doi=10.1073/pnas.0935845100|bibcode=2003PNAS..100.5497C|doi-access=free}}

Observing video clips that displayed facial expressions indicating disgust activated the neural networks typical of direct experience of disgust.{{cite journal|author1=Wicker, B.|author2=Keysers, C.|author3=Plailly, J.|author4=Royet, J. P.|author5=Gallese, V.|author6=Rizzolatti, G.|name-list-style=amp|year=2003|title=Both of us disgusted in my insula: The common neural basis of seeing and feeling disgust|journal=Neuron|volume=40|issue=3|pages=655–664|pmid=14642287|doi=10.1016/S0896-6273(03)00679-2|doi-access=free}} Similar results have been found in the case of touch. Watching movies in which someone touched legs or faces activated the somatosensory cortex for direct feeling of the touch.{{cite journal|author1=Keysers, C.|author2=Wicker, B.|author3=Gazzola, V.|author4=Anton, J. L.|author5=Fogassi, L.|author6= Gallese, V.|name-list-style=amp|year=2004|title=A touching sight: SII/PV activation during the observation and experience of touch|journal=Neuron|volume=42|issue=2|pages=335–346|pmid=15091347|doi=10.1016/S0896-6273(04)00156-4|doi-access=free}} A similar mirror system exists in perceiving pain. When people see other people feel pain, people feel pain not only affectively,{{cite journal|author1=Avenanti, A.|author2=Paluello, L. M.|author3=Bufalari, I.|author4=Aglioti, S. M.|name-list-style=amp|year=2006|title=Stimulus-driven modulation of motor-evoked potentials during observation of others' pain|journal=NeuroImage|volume=32|issue=1|pages=316–324|pmid=16675270|doi=10.1016/j.neuroimage.2006.03.010|s2cid=23907332}} but also sensorially.{{cite journal|author1=Singer, T.|author2=Seymour, B.|author3=O'Doherty, J.|author4=Kaube, H.|author5=Dolan, R. J.|author6=Frith, C. D.|name-list-style=amp|year=2004|title=Empathy for pain involves the affective but not sensory components of pain|journal=Science|volume=303|issue=5661|pages=1157–1162|pmid=14976305|doi=10.1126/science.1093535|jstor=3836287|bibcode=2004Sci...303.1157S|hdl=21.11116/0000-0001-A020-5|s2cid=14727944|hdl-access=free}}

These results suggest that understanding another's feelings and emotions is driven not by cognitive deduction of what the stimuli means but by automatic activation of somatosensory neurons. A recent study on pupil size directly demonstrated emotion perception as an automatic process modulated by mirror systems.{{cite journal|author1=Harrison, N. A.|author2=Singer, T.|author3=Rotshtein, P.|author4=Dolan, R. J.|author5=Critchley, H. D.|name-list-style=amp|year=2006|title=Pupillary contagion: Central mechanisms engaged in sadness processing|journal=SCAN|volume=1|issue=1|pages=5–17|pmid=17186063|doi=10.1093/scan/nsl006|pmc=1716019}} When people saw sad faces, pupil sizes influenced viewers in perceiving and judging emotional states without explicit awareness of differences of pupil size. When pupil size was 180% of original size, people perceived a sad face as less negative and less intense than when pupil was smaller than or equal to original pupil size. This mechanism was correlated with brain regions implicated in emotion processing, such as the amygdala. Viewers mirror the size of their own pupils to those of sad faces they watch. Considering that pupil size is beyond voluntary control, the change of pupil size upon emotion judgment is a good indication that understanding emotions is automatic process. However, the study could not find that other emotional faces, such as faces displaying happiness and anger, influence pupil size as sadness did.

Based on findings from neuroimaging studies, de Vignemont and Singer proposed empathy as a crucial factor in human communication: "Empathy might enable us to make faster and more accurate predictions of other people's needs and actions and discover salient aspects of our environment."{{cite journal|author1=de Vignemont, F.|author2=Singer, T.|name-list-style=amp|year=2006|title=The empathic brain: How, when and why?|journal=Trends in Cognitive Sciences|volume=10|issue=10|pages=435–441|pmid=16949331|doi=10.1016/j.tics.2006.08.008|s2cid=11638898|url=https://jeannicod.ccsd.cnrs.fr/ijn_00169584/file/empathy_TICS.pdf}} Mental mirroring of actions and emotions may enable humans to understand other's actions and their related environment quickly, and thus help humans communicate efficiently.

In an fMRI study, a mirror system has been proposed as common neural substrate that mediates the experience of basic emotions.{{cite journal|author1=Chakrabarti, B.|author2=Bullmore, E.|author3=Baron-Cohen, S.|name-list-style=amp|year=2006|title=Empathizing with basic emotions: Common and discrete neural substrates|journal=Social Neuroscience|volume=1|issue=3&4|pages=364–384|pmid=18633800|doi=10.1080/17470910601041317|s2cid=18612627}} Participants watched video clips of happy, sad, angry, and disgusted facial expressions, and researchers measured their empathy quotient (EQ). Specific brain regions relevant to the four emotions were found to be correlated with the EQ while the mirror system (i.e., the left dorsal inferior frontal gyrus/premotor cortex) was correlated to the EQ across all emotions. The authors interpreted this result as an evidence that action perception mediates face perception to emotion perception.

A paper published in Science challenges the idea that pain sensations and mirror neurons play a role in empathy for pain. Specifically, the authors found that activity in the anterior insula and the anterior cingulate cortex (two regions known to be responsible for the affective experience of pain) was present both when one's self and when another person were presented with a painful stimulus, but the rest of the pain matrix responsible for sensation was not active. Furthermore, participants merely saw the hand of another person with the electrode on it, making it unlikely that "mirroring" could have caused the empathic response. However, a number of other studies, using magnetoencephalography and functional MRI have since demonstrated that empathy for pain does involve the somatosensory cortex, which supports the simulation theory.{{cite journal|author1=Cheng, Y.|author2=Yang, C.Y.|author3=Lin, C.P.|author4=Lee, P.R.|author5= Decety, J.|name-list-style=amp|year=2008|title=The perception of pain in others suppresses somatosensory oscillations: a magnetoencephalography study|journal=NeuroImage|volume=40|issue=4|pages=1833–1840|pmid=18353686|doi=10.1016/j.neuroimage.2008.01.064|s2cid=1827514}}

• {{cite journal|author1=Moriguchi, Y.|author2=Decety, J.|author3=Ohnishi, T.|author4=Maeda, M.|author5=Matsuda, H.|author6=Komaki, G. |name-list-style=amp|year=2007|title=Empathy and judging other's pain: An fMRI study of alexithymia|journal=Cerebral Cortex|volume=17|issue=9|pages=2223–2234|pmid=17150987|doi= 10.1093/cercor/bhl130|doi-access=free}}
• {{cite journal|author1=Lamm, C.|author2=Nusbaum, H.C.|author3=Meltzoff, A.N.|author4=Decety, J.|name-list-style=amp|year=2007|title=What are you feeling? Using functional magnetic resonance imaging to assess the modulation of sensory and affective responses during empathy for pain|journal=PLOS ONE|volume=2|issue=12|pages=e1292|pmid=18091986|pmc=2144768|doi=10.1371/journal.pone.0001292|bibcode=2007PLoSO...2.1292L|doi-access=free}}
• {{cite journal|author1=Ogino, Y.|author2=Nemoto, H.|author3=Inui, K.|author4=Saito, S.|author5=Kakigi, R.|author6=Goto, F.|name-list-style=amp|year=2007|title=Inner experience of pain: imagination of pain while viewing images showing painful events forms subjective pain representation in human brain|journal=Cerebral Cortex|volume=17|issue=5|pages=1139–1146|pmid=16855007|doi=10.1093/cercor/bhl023|doi-access=free}}

Support for the anterior insula and anterior cingulate cortex being the neural substrates of empathy include Wicker et al., 2003 who report that their "core finding is that the anterior insula is activated both during observation of disgusted facial expressions and during the emotion of disgust evoked by unpleasant odorants."{{r|Wicker2003|p=655}}

Furthermore, one study demonstrated that "for actions, emotions, and sensations both animate and inanimate touch activates our inner representation of touch." They note, however that "it is important at this point to clarify the fact that we do not believe that the activation we observe evolved in order to empathize with other objects or human beings"{{r|auto1|p=343}}

{{Also|Empathy-altruism}}

This model states that empathy activates only one interpersonal motivation: altruism. Theoretically, this model makes sense, because empathy is an other-focused emotion. There is an impressive history of research suggesting that empathy, when activated, causes people to act in ways to benefit the other, such as receiving electric shocks for the other.{{cite journal|last=Batson|first=C. D|title=The Altruism Question: Toward a Social-Psychological Answer|year=1991}}

• {{cite book|last=Batson|first=C. D.|author2=Gilbert, D. T. |author3=Fiske, S. T. |author4=Lindzey, G. |title=The handbook of social psychology|year=1998}} These findings have often been interpreted in terms of empathy causing increased altruistic motivation, which in turn causes helping behavior.

• Mentalization
• Moral emotions
• Perspective-taking
• Social emotions
• Theory of mind

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Category:Psychological theories

Category:Motor cognition

Category:Empathy