Theory of mind and mirroring neurons
Authors: Jay Schulkin
Journal: Trends in Cognitive Sciences (2000)

Two very interesting papers in this journal are worthy of further comment. One was by Vittorio Gallese and Alvin Goldman entitled ‘Mirror neurons and the simulation theory of mind-reading’1Gallese V. Goldman A. Mirror neurons and the simulation theory of mind reading.Trends Cognit. Sci. 1999; 2: 493-501Abstract Full Text Full Text PDF Scopus (2144) Google Scholar, and the other by Ralph Adolphs entitled ‘Social cognition and the human brain’2Adolphs R. Social cognition and the human brain.Trends Cognit. Sci. 1999; 3: 469-479Abstract Full Text Full Text PDF PubMed Scopus (669) Google Scholar. Both articles highlighted and raised issues about the status of simulation theory of mind in the context of mirror neurons. Both also pointed to recent experiments in cognitive neuroscience and their implications for understanding the mechanisms that underlie the ability to understand other people (or, more generally, conspecifics). Some groups of premotor neurons are often called ‘mirroring neurons’ (or mirror neurons) because they are activated by performing and/or observing intentional action. The question is whether these mirroring neurons need first person (‘simulation theory’) or third person (‘theory-theory’) access to an event with regard to understanding the intentional states of others. I will begin with a brief discussion of first and third person perspective. Issues about first and third person perspective-taking recreates the old argument by analogy, in the hands of simulation theorists3Caruthers P. Smith P.K. Theories of Theories of Mind. Cambridge University Press, 1996Crossref Google Scholar. I know something about you, the old argument went, in so far as I can extend my experiences to you by analogy. Simulation theory is a modern variant of the argument by analogy. The argument by analogy as foundational for knowing others has been criticized by a great number of investigators in this century: the counter-argument is that we know a lot about the world and other peoples’ experiences even when there is no corresponding experience in us4Peirce C.S. Some consequences of four incapacities.J. Speculative Philos. 1868; : 140-157Google Scholar. What was attacked was the idea of having to look inward to know others, like the idea of having to look inward to know something about the world, and rightfully so5Wittgenstein L. Philosophical Investigations. Macmillan, 1953Google Scholar. (I am by no means advocating a return to an intellectually bankrupt behaviorism; the cognitive revolution changed the landscape of modern psychology6Schulkin J. Pragmatism and the cognitive and neural sciences.Psychol. Rep. 1996; 78: 499-506Crossref PubMed Scopus (1) Google Scholar.) The statement ‘I watch your envious thought of your brother’s success’ does not mean that I first think of my brother, and then think of you and your brother. I can just be thinking about you, the world and the social milieu in which I view you. But might one have had to have experienced envy? Yes, probably. Experience matters. The question is, to what degree? Looking inward is no measure of truth, and moreover, the mechanisms that allow learning about the world are not typically part of what one sees internally, in as much as one sees anything. Simulation theory does a disservice by suggesting that my coming to know another person means by necessity that I first have to turn inward to my own experience. I can learn, thankfully, many things about other people that have no bearing upon my own experience. That is not to say I don’t draw on my experience; obviously we do. But the capacity to imagine who you are is a cognitive achievement, without having to look inward. Thus, I see no reason to return to the traditional view that we only attribute to others what we find in ourselves. The ‘introspective mind’ popularized, and importantly so, by Nicholas Humphrey7Humphrey N.C. A History of the Mind. Harper, 1992Crossref Google Scholar should not become a criterion for social cognition. Much of what goes on when we reason about others is not introspection in the classical sense of looking in on the contents of mind. Several of the developmental psychologists hold the theory-theory position (e.g. 8Gopnik A. How we know our minds.Behav. Brain Sci. 1992; 16: 1-14Crossref Google Scholar). This view is close to Hanson’s theory-laden view of science9Hanson N.R. Patterns of Discovery. Cambridge University Press, 1958Google Scholar. For these developmental psychologists, learning about you or me is theoretical. In fact, mini theories are the parlance of young children and older adults. The question is to what degree; and that is an empirical question. Peirce noted that ‘all inference is hypothetical’10Peirce C.S. Questions concerning certain faculties claimed for man.J. Speculative Philos. 1868; : 103-114Google Scholar. There is no privileged status: all seeing is from a background framework of inferences, whether of first- or third-person perspective9Hanson N.R. Patterns of Discovery. Cambridge University Press, 1958Google Scholar. Thus, the contents of the mind are as theoretical as the contents of the kidney. The workings of the loops of Henle in the kidney are not more available to inspection than the mechanisms that underlie short-term memory. Nothing is simply transparent or indubitable. Consider the following scenario, which perhaps might differentiate simulation theory from theory-theory. When confronted with something other than first-person experience it should take longer for that person to figure something out, or perhaps they won’t figure it out at all if they cannot find the experience internally first. Looking inward and then outward and then somehow measuring the difference or similarity is the cornerstone of simulation. Thus the more different the two experiences are, the longer will be the time for working it out (if at all), in the view of the simulation theorists. In other words, simulation is a two-step process and laborious. I am not disputing that we do this. But it is not clear to what extent. In real life, the computational mechanisms are not particularly conscious; and it is theory laden if one looks in or looks out at first blush. The problem with the alternative view is that ‘theory’ (third person perspective) sounds cold and detached and divorced from experience. It is unfortunate that theory is often characterized as the abstract, and experience as the concrete; theory as distant, simulation as close and upfront. A sophisticated and common way to characterize theory in the context of knowing another is ‘the knowledge that I have of her and her past life–knowledge which is necessary for this sort of prediction – [but which] is clearly not theoretical knowledge’11Goldie P. How we think of others’ emotions.Mind Lang. 1999; 14: 394-421Crossref Scopus (69) Google Scholar. But if theory means systematic inferences made on the basis of background assumptions, then whether it is first person or third person, theory is presupposed in both contexts. Moreover, in either case, some outlooks are up close and personal, others are not. Even the distinction of the abstract (concept) and the concrete (particular) has its roots in classical thought and is present in modern cognitive science. I am not denying this distinction, but I am questioning the way it is used in understanding how we learn from each other. Theory (a set of concepts and inferences) is active in our interactions, whether we look inward, or outward on others. The same cognitive and neural mechanisms are recruited in both contexts. The best evidence for the existence of mirroring neurons come from primate studies of the frontal area of the brain. Populations of mirror neurons have been recorded from these frontal regions in macaques1Gallese V. Goldman A. Mirror neurons and the simulation theory of mind reading.Trends Cognit. Sci. 1999; 2: 493-501Abstract Full Text Full Text PDF Scopus (2144) Google Scholar, 12Gallese V. et al.Action recognition in the premotor cortex.Brain. 1996; 119: 593-609Crossref PubMed Scopus (3584) Google Scholar. Specific neurons fire when the macaque is shown a specific hand movement and these same neurons also fire when the macaque is performing that movement (e.g. 12Gallese V. et al.Action recognition in the premotor cortex.Brain. 1996; 119: 593-609Crossref PubMed Scopus (3584) Google Scholar). In other words, it was found that premotor cortex is active both when monkeys observe simple movements and when they perform them. In human brain-imaging studies, when people were asked to imagine or actually grasp an object, regions of the brain linked to movement were activated13Decety J. et al.Mapping motor representations with positron emission tomography.Nature. 1994; 371: 600-602Crossref PubMed Scopus (840) Google Scholar. These regions included Brodmann area 6 in the inferior part of the frontal gyrus of both cortical hemispheres, the anterior cingulate regions and the ventral parietal lobe. Interestingly, both the caudate nucleus of the basal ganglia and regions of the cerebellum were also activated. Moreover, a neural system that matches or imitates movement has been shown to include neurons within the left inferior frontal cortex and the caudal region of the right superior parietal lobe – these areas are active when human subjects are asked to observe and imitate finger movements14Iacoboni M. et al.Cortical mechanisms of human imitation.Science. 1991; 286: 2526-2528Crossref Scopus (2099) Google Scholar. How are we to interpret these observations? Gallese and Goldman1Gallese V. Goldman A. Mirror neurons and the simulation theory of mind reading.Trends Cognit. Sci. 1999; 2: 493-501Abstract Full Text Full Text PDF Scopus (2144) Google Scholar are simulation theorists; however, on first glance, I believe they have a mistaken view of theory. For them, the difference between the theory-theory view and simulation theory is that the theory-theory view is ‘thoroughly detached’ (1Gallese V. Goldman A. Mirror neurons and the simulation theory of mind reading.Trends Cognit. Sci. 1999; 2: 493-501Abstract Full Text Full Text PDF Scopus (2144) Google Scholar, p. 497). Why detached? Looking out does not mean detached, or not drawing on one’s own or others’ history. It is not an either/or affair in real life. Gallese and Goldman’s point is that ‘mirror neuron activity is not mere theoretical inference’ (p. 498). But why not? One could be detached and putatively be looking inward, and not be detached and looking outward. The interesting fact here is that there are neurons in the brain that subserve the doing, and the watching of others doing, an action. But simply calling these ‘mirror neurons’ is independent, I would submit, of the simulation- versus the theory-theory view. The important finding is that these neurons underlie observation and orchestration of goal-directed action patterns, and perhaps underlie the perception of intentional action. In his article, Ralph Adolphs presents the interesting idea that ‘simulation may be the only option in cases that are sufficiently idiosyncratic, or in cases where the information is not easily encoded into language. In the latter situation, it could be that the only way to predict what another person will do is to run in one’s own brain the processes that the other person is running in theirs. If this possibility is taken seriously it suggests a role for conscious experience in social cognition: to obtain information about another person’s internal mental state, it may be necessary to imagine what it would be like to be the other person via direct simulation.’ (2Adolphs R. Social cognition and the human brain.Trends Cognit. Sci. 1999; 3: 469-479Abstract Full Text Full Text PDF PubMed Scopus (669) Google Scholar, p. 476). He then goes on to suggest that ‘simulation might find its developmental origins in the infant’s ability to mimic facial expressions…’. Simulation theory suggests, though mistakenly I believe, that sensory experiences are entirely distinct from theory building. This is perhaps reflected in one misleading claim in the developmental literature, in which desires are construed as primitive and preceding beliefs in the developmental calendar15Wellman H.M. Woolley J.D. From simple desires to ordinary beliefs: the early development of everyday psychology.Cognition. 1990; 35: 245-275Crossref PubMed Scopus (427) Google Scholar. Some of the evidence to support this claim is that two-year-olds emit more talk about desires than about belief. Evidence is provided that two-year-olds easily work with imaginary objects in which the character acts out wanting something, but when queried about beliefs they do less well15Wellman H.M. Woolley J.D. From simple desires to ordinary beliefs: the early development of everyday psychology.Cognition. 1990; 35: 245-275Crossref PubMed Scopus (427) Google Scholar. But at that age, the storehouse of knowledge to have beliefs about is limited16Fodor J.A. A theory of the child’s theory of mind.Cognition. 1992; 44: 283-296Crossref PubMed Scopus (354) Google Scholar. At other times it has been suggested that children understand other people’s mental states in intentional but not representational terms. I am not sure what this means, because intentionality presupposes the existence of propositional attitudes17Rey G. Contemporary Philosophy of Mind. Blackwell, 1997Google Scholar and propositional attitudes are surely representational. On Wellman’s and Woolley’s view15Wellman H.M. Woolley J.D. From simple desires to ordinary beliefs: the early development of everyday psychology.Cognition. 1990; 35: 245-275Crossref PubMed Scopus (427) Google Scholar, for example, young children understand what others might want, but not what they believe. I do not disagree with this. A simple desire-psychology allows children to understand a limited number of objects, and this is increased with the onset of beliefs. The storehouse of knowledge accrues with understanding about where objects come from. But these assumptions, I am afraid, rest on a false distinction – desires about apples presuppose beliefs about objects: they are good to eat, they are safe, and so on. How can you desire something without having beliefs about it? It is not as if desires aren’t theory-laden. Again, perhaps, the difference is the degree of complexity and the storehouse of knowledge of desires versus beliefs. This is not to deny that desires are not different from beliefs – they are. One such difference is that beliefs either have or do not have truth-value; this is not true of desires. The distinction between desires and beliefs is consistent with the empiricist view of desires unmediated by thoughts, like sensations unmediated by cognition, or emotions unmediated by cognition18Parrott W.G. Schulkin J. Neuropsychology and the cognitive nature of the emotions.Cognit. Emot. 1993; 1: 43-49Crossref Scopus (59) Google Scholar. A more troublesome aspect, though, of the separation of desires and beliefs is that it resurrects a philosophical problemat that has cast a long intellectual shadow. Desires are not more indubitable than beliefs. Certainty of that kind is just what one must give up19Dewey J. The Quest for Certainty. Putnam & Sons, 1929Google Scholar. Perhaps we are in a better position if we separate these issues from consciousness, for then one is suggesting only that the mechanisms for imagination are similar to those of actual engagement. The discussion of mechanisms is quite different from whether the child really has something available to his conscious experience. In all this, the exciting finding is that an emerging cognitive neuroscience has implicated a number of key brain areas that are fundamental in social cognition, as was elegantly described by Adolphs in his paper. Interestingly, common regions of my brain are active whether I reach for an object or I observe you doing so. Understanding social interactions involves four key areas of the brain: frontal and temporal cortex, the amygdala and perhaps the basal ganglia (e.g. 20Baron-Cohen S. et al.Social intelligence in the normal and autistic brain: an fMRI study.Eur. J. Neurosci. 1999; 11: 1891-1898Crossref PubMed Scopus (1120) Google Scholar, 21Frith C.D. Frith U. Interacting minds-biological basis.Science. 1999; 286: 1692-1695Crossref PubMed Scopus (1343) Google Scholar).