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Theory of mind (often abbreviated ToM) is the ability to attribute mental states — beliefs, intents, desires, pretending, knowledge, etc. — to oneself and others and to understand that others have beliefs, desires, and intentions that are different from one's own. Deficits occur in people with autism spectrum disorders, schizophrenia, attention deficit hyperactivity disorder, as well as neurotoxicity due to alcohol abuse. Although there are philosophical approaches to this, the theory of mind as such is distinct from the philosophy of mind.
Theory of mind is a theory insofar as the mind is not directly observable. The presumption that others have a mind is termed a theory of mind because each human can only intuit the existence of his/her own mind through introspection, and no one has direct access to the mind of another. It is typically assumed that others have minds by analogy with one's own, and this assumption is based on the reciprocal nature of social interaction, as observed in joint attention, the functional use of language, and understanding of others' emotions and actions. Having a theory of mind allows one to attribute thoughts, desires, and intentions to others, to predict or explain their actions, and to posit their intentions. As originally defined, it enables one to understand that mental states can be the cause of—and thus be used to explain and predict—the behavior of others. Being able to attribute mental states to others and understanding them as causes of behavior implies, in part, that one must be able to conceive of the mind as a "generator of representations". If a person does not have a complete theory of mind it may be a sign of cognitive or developmental impairment.
Theory of mind appears to be an innate potential ability in humans, but one requiring social and other experience over many years to bring to fruition. Different people may develop more, or less, effective theories of mind. Empathy is a related concept, meaning the recognition and understanding the states of mind of others, including their beliefs, desires and particularly emotions. This is often characterized as the ability to "put oneself into another's shoes". Recent neuro ethological studies of animal behaviour suggest that even rodents may exhibit ethical or empathic abilities. Neo-Piagetian theories of cognitive development maintain that theory of mind is a byproduct of a broader hypercognitive ability of the human mind to register, monitor, and represent its own functioning.
Research on theory of mind, in humans and animals, adults and children, normally and atypically developing, has grown rapidly in the 35 years since Premack and Woodruff's paper, "Does the chimpanzee have a theory of mind?". The emerging field of social neuroscience has also begun to address this debate, by imaging the brains of humans while they perform tasks demanding the understanding of an intention, belief or other mental state in others.
An alternative account of theory of mind is given within operant psychology and provides significant empirical evidence for a functional account of both perspective taking and empathy. The most developed operant approach is founded on research on derived relational responding and is subsumed within what is called, "Relational Frame Theory". According to this view empathy and perspective taking comprise a complex set of derived relational abilities based on learning to discriminate and respond verbally to ever more complex relations between self, others, place, and time, and the transformation of function through established relations.
Contemporary discussions of ToM have their roots in philosophical debate—most broadly, from the time of Descartes' Second Meditation, which set the groundwork for considering the science of the mind. Most prominent recently are two contrasting approaches in the philosophical literature, to theory of mind: theory-theory and simulation theory. The theory-theorist imagines a veritable theory—"folk psychology"—used to reason about others' minds. The theory is developed automatically and innately, though instantiated through social interactions.
On the other hand, simulation theory (ST) suggests ToM is not, at its core, theoretical. According to simulation theorists, the primary method for understanding the minds of others that people employ is simply to place themselves "in the mental shoes" of the other. This idea that is also explicit in the "golden rule": "Treat others as you would like to be treated". In other words, imagine how you might react to someone else doing an action to you before you do the same action to someone else. ST involves three steps:
There are a number of different accounts of ST, each of which relies heavily upon the activity of mirror neurons. Arguably the consensus view is the "direct matching" hypothesis. According to this theory, mirror neurons actually "mirror" the state of the target in the observer. This mirroring elicits a similar emotion or intention in the observer, which is then implicitly or explicitly projected upon the target. The observer then infers the meaning or intention of the target using this information.
An alternative simulation theory has been proposed, the "inverse modeling" hypothesis. According to this view, the actions of mirror neurons simulate the intended goal of an action first. After this motor simulation, the observer uses his/her conceptual abilities to infer the intention of the action. By this model, the role of mirror neurons is an instrumental tool that can be used to guess the meaning of intentional behavior by producing a model of that behavior in context to aid understanding.
Another simulation theory that tries to account for broadly congruent mirror neurons is the response modeling theory. These theorists propose that the function of mirror neurons in social cognition is not so much to "mirror" the target’s action. Rather, the function is to instantly prepare a complementary action in response to the target. They dynamically couple action observation to action execution. The impetus for this view was the discovery that mirror neurons are actually more active when preparing for a complementary action rather than an imitative action. In other words, the function of some mirror neurons is to instantly anticipate and prepare a response to an observed action.
Two additional kinds of simulationism have been proposed. One version (Alvin Goldman's) emphasizes that one must recognize one's own mental states before ascribing mental states to others by simulation. The second version of simulation theory proposes that each person comes to know his or her own and others' minds through what Robert Gordon names a logical ascent routine, which answers questions about mental states by re-phrasing the question as a metaphysical one. For example, if Zoe asks Pam, "Do you think that dog wants to play with you?", Pam would ask herself, "Does that dog want to play with me?" to determine her own response. She could equally well ask that to answer the question of what Zoe might think. Both hold that people generally understand one another by simulating being in the other's shoes.
One of the differences between the two theories that have influenced psychological consideration of ToM is that theory-theory describes ToM as a detached theoretical process that is an innate feature, whereas simulation theory portrays ToM as a kind of knowledge that allows one to form predictions of someone's mental states by putting oneself in the other person's shoes and simulating them. These theories continue to inform the definitions of theory of mind at the heart of scientific ToM investigation.
Recently other accounts of our ability to know the minds of others have been proposed. For example, interaction theory, a recent theory based on Shaun Gallagher's work, rejects the standard interpretations as being overly "mental". In interaction theory, the minds of others are directly perceived during intersubjective encounters. According to IT, very little mentalizing occurs in our day-to-day interactions. Rather than first perceiving another's actions and then inferring the meaning of their actions, the intended meaning is automatically apparent upon perception. Hidden away mental states like "beliefs" and "desires" are therefore unnecessary to explain behavior. We can see the meaning of their behavior through their actions and expressive movements. For example, upon seeing an angry face an observer does not see first a face that is contorted into a scowl and then infer that the target is angry. The anger is immediately apparent on the face of the other. The overwhelming majority of interactions in our daily lives are face-to-face so it makes sense that our primary way of understanding one another is from a second-person perspective rather than a detached, theoretical, third-person perspective.
"In most intersubjective situations, that is, in situations of social interaction, we have a direct perceptual understanding of another person's intentions because their intentions are explicitly expressed in their embodied actions and their expressive behaviors. This understanding does not require us to postulate or infer a belief or a desire hidden away in the other person's mind. What we might reflectively or abstractly call their belief or desire is expressed directly in their actions and behaviors".
This ability has been termed "primary intersubjectivity" and includes emotional, sensory-motor, perceptual, and nonconceptual embodied practices that are exhibited by pre-linguistic children. It is considered "primary" for two reasons: (1) Ontogenetically it is the earliest appearing intersubjective abilities in children, and (2) even into adulthood it remains the most essential ability that we utilize in interacting and understanding others. These abilities are multimodal and nonconceptual, which is evident in well-known experiments regarding neonate imitation. In these experiments the neonate is only minutes old and therefore does not have conceptual abilities; yet the neonate can imitate the facial expressions of others, which is a multimodal process that requires a nonconceptual connection between visual stimulus and the neonates own facial configuration.
Furthermore, the fact that most interactions take place in cooperative contexts leads to "secondary intersubjectivity". During most interactions, intentions are apparent based upon the pragmatic context of the situation in which they are occurring. We can instantly see what the other "intends" or "wants" based upon their actions and the current context; we do not need to infer their intentions as if they are hidden away. There is a "shared world" that we live in where we intuitively and instinctively perceive others as minded beings like ourselves. Dan Zahavi echoed these sentiments when he wrote, "it is not the case that we first see inanimate objects and then animate them through a subsequent addition of mental components. Rather, at first we see everything as expressive, and then we go through a process of de-animation".
The intuitive assumption that others are minded is an apparent tendency we all share. We anthropomorphize non-human animals, inanimate objects, and even natural phenomenon. Daniel Dennett referred to this tendency as taking an "intentional stance" toward things: we assume they have intentions, to help predict future behavior. However, there is an important distinction between taking an "intentional stance" toward something and entering a "shared world" with it. The intentional stance is a detached and functional theory we resort to during interpersonal interactions. A shared world is directly perceived and its existence structures reality itself for the perceiver. It is not just automatically applied to perception; it in many ways constitutes perception.
The philosophical roots of the Relational Frame Theory account of ToM arise from contextual psychology and refer to the study of organisms (both human and non-human) interacting in and with a historical and current situational context. It is an approach based on contextualism, a philosophy in which any event is interpreted as an ongoing act inseparable from its current and historical context and in which a radically functional approach to truth and meaning is adopted. As a variant of contextualism, RFT focuses on the construction of practical, scientific knowledge. This scientific form of contextual psychology is virtually synonymous with the philosophy of operant psychology.
The study of which animals are capable of attributing knowledge and mental states to others, as well as when in human ontogeny and phylogeny this ability developed, has identified a number of precursory behaviors to a theory of mind. Understanding attention, understanding of others' intentions, and imitative experience with other people are hallmarks of a theory of mind that may be observed early in the development of what later becomes a full-fledged theory. In studies with non-human animals and pre-verbal humans, in particular, researchers look to these behaviors preferentially in making inferences about mind.
Simon Baron-Cohen identified the infant's understanding of attention in others, a social skill found by 7 to 9 months of age, as a "critical precursor" to the development of theory of mind. Understanding attention involves understanding that seeing can be directed selectively as attention, that the looker assesses the seen object as "of interest", and that seeing can induce beliefs. Attention can be directed and shared by the act of pointing, a joint attention behavior that requires taking into account another person's mental state, particularly whether the person notices an object or finds it of interest. Baron-Cohen speculates that the inclination to spontaneously reference an object in the world as of interest ("protodeclarative pointing") and to likewise appreciate the directed attention and interests of another may be the underlying motive behind all human communication.
Understanding of others' intentions is another critical precursor to understanding other minds because intentionality, or "aboutness", is a fundamental feature of mental states and events. The "intentional stance" has been defined by Daniel Dennett as an understanding that others' actions are goal-directed and arise from particular beliefs or desires. Both 2- and 3-year-old children could discriminate when an experimenter intentionally vs. accidentally marked a box as baited with stickers. Even earlier in ontogeny, Andrew N. Meltzoff found that 18 month-old infants could perform target manipulations that adult experimenters attempted and failed, suggesting the infants could represent the object-manipulating behavior of adults as involving goals and intentions. While attribution of intention (the box-marking) and knowledge (false-belief tasks) is investigated in young humans and nonhuman animals to detect precursors to a theory of mind, Gagliardi et al. have pointed out that even adult humans do not always act in a way consistent with an attributional perspective. In the experiment, adult human subjects made choices about baited containers when guided by confederates who could not see (and therefore, not know) which container was baited.
Recent research in developmental psychology suggests that the infant's ability to imitate others lies at the origins of both a theory of mind and other social-cognitive achievements like perspective-taking and empathy. According to Meltzoff, the infant's innate understanding that others are "like me" allows it to recognize the equivalence between the physical and mental states apparent in others and those felt by the self. For example, the infant uses his own experiences orienting his head/eyes toward an object of interest to understand the movements of others who turn toward an object, that is, that they will generally attend to objects of interest or significance. Some researchers in comparative disciplines have hesitated to put a too-ponderous weight on imitation as a critical precursor to advanced human social-cognitive skills like mentalizing and empathizing, especially if true imitation is no longer employed by adults. A test of imitation by Alexandra Horowitz found that adult subjects imitated an experimenter demonstrating a novel task far less closely than children did. Horowitz points out that the precise psychological state underlying imitation is unclear and cannot, by itself, be used to draw conclusions about the mental states of humans.
Whether children younger than 3 or 4 years old may have a theory of mind is a topic of debate among researchers. It is a challenging question, due to the difficulty of assessing what pre-linguistic children understand about others and the world. Tasks used in research into the development of ToM must take into account the umwelt—(the German word Umwelt means "environment" or "surrounding world")—of the pre-verbal child.[clarification needed]
One of the most important milestones in theory of mind development is gaining the ability to attribute false belief: that is, to recognize that others can have beliefs about the world that are diverging. To do this, it is suggested, one must understand how knowledge is formed, that people's beliefs are based on their knowledge, that mental states can differ from reality, and that people’s behavior can be predicted by their mental states. Numerous versions of the false-belief task have been developed, based on the initial task done by Wimmer and Perner (1983).
In the most common version of the false-belief task (often called the "'Sally-Anne' test" or "'Sally-Anne' task"), children are told or shown a story involving two characters. For example, the child is shown two dolls, Sally and Anne, who have a basket and a box, respectively. Sally also has a marble, which she places in her basket, and then leaves the room. While she is out of the room, Anne takes the marble from the basket and puts it in the box. Sally returns, and the child is then asked where Sally will look for the marble. The child passes the task if she answers that Sally will look in the basket, where she put the marble; the child fails the task if she answers that Sally will look in the box, where the child knows the marble is hidden, even though Sally cannot know this, since she did not see it hidden there. To pass the task, the child must be able to understand that another’s mental representation of the situation is different from their own, and the child must be able to predict behavior based on that understanding.
Another example is when a boy leaves chocolate on a shelf and then leaves the room. His mother puts it in the fridge. To pass the task, the child must understand that the boy upon returning holds the false belief that his chocolate is still on the shelf.
The results of research using false-belief tasks have been fairly consistent: most normally developing children are unable to pass the tasks until around age four. (Notably, while most children, including those with Down syndrome, are able to pass this test, in one study, 80% of children diagnosed with autism were unable to do so.)
Also adults can experience problems with false beliefs, for instance when they show hindsight bias, which can be defined as: “the inclination to see events that have already happened as being more predictable than they were before they took place.”  For instance, in an experiment by Fischhoff in 1975, adult subjects who were asked for an independent assessment were unable to disregard information on actual outcome. Also in experiments with complicated situations, when assessing others' thinking, adults can be unable to disregard certain information that they have been given.
Other tasks have been developed to try to solve the problems inherent in the false-belief task. In the "appearance-reality", or "Smarties" task, experimenters ask children what they believe to be the contents of a box that looks as though it holds a candy called "Smarties". After the child guesses (usually) "Smarties", it is shown that the box in fact contained pencils. The experimenter then re-closes the box and asks the child what she thinks another person, who has not been shown the true contents of the box, will think is inside. The child passes the task if he/she responds that another person will think that there are "Smarties" in the box, but fails the task if she responds that another person will think that the box contains pencils. Gopnik & Astington (1988) found that children pass this test at age four or five years.
The "false-photograph" task is another task that serves as a measure of theory of mind development. In this task, children must reason about what is represented in a photograph that differs from the current state of affairs. Within the false-photograph task, there is either a location or identity change. In the location-change task, the examiner puts an object in one location (e.g., chocolate in an open green cupboard), whereupon the child takes a Polaroid photograph of the scene. While the photograph is developing, the examiner moves the object to a different location (e.g., a blue cupboard), allowing the child to view the examiner's action. The examiner asks the child two control questions: "When we first took the picture, where was the object?" and "Where is the object now?". The subject is also asked a "false-photograph" question: "Where is the object in the picture?" The child passes the task if he/she correctly identifies the location of the object in the picture and the actual location of the object at the time of the question. However, the last question might be misinterpreted as: "Where in this room is the object that the picture depicts?" and therefore some examiners use an alternative phrasing.
To make it easier for animals, young children, and individuals with classical (Kanner-type) autism to understand and perform theory-of-mind tasks, researchers have developed tests in which verbal communication is de-emphasized: some whose administration does not involve verbal communication on the part of the examiner, some whose successful completion does not require verbal communication on the part of the subject, and some that meet both of the foregoing standards. One category of tasks uses a preferential looking paradigm, with looking time as the dependent variable. For instance, 9-month-old infants prefer looking at behaviors performed by a human hand over those made by an inanimate hand-like object. Other paradigms look at rates of imitative behavior, the ability to replicate and complete unfinished goal-directed acts, and rates of pretend play.
Recent research on the early precursors of theory of mind have looked at innovative ways at capturing prelinguistic infants' understanding of other people's mental states, including perception and beliefs. Using a variety of experimental procedures, studies have shown that infants in their second year of life have an implicit understanding what other people see and what they know. A popular paradigm used to study infants' theory of mind is the violation of expectation procedure, which predicates on infants' tendency to look longer at unexpected and surprising events compared to familiar and expected events. Therefore, their looking times measures would give researchers an indication of what infants might be inferring, or their implicit understanding of events. One recent study using this paradigm found that 16-month-olds tend to attribute beliefs to a person whose visual perception was previously witnessed as being "reliable" compared to someone whose visual perception was "unreliable". Specifically, 16-month-olds were trained to expect a person's excited vocalization and gaze into a container to be associated with finding a toy in the reliable looker condition or an absence of a toy in the unreliable looker condition. Following this training phase, infants witnessed, in an object-search task, the same person either searching for a toy in the correct or incorrect location after they both witnessed the location of where the toy was hidden. Infants who experienced the reliable looker were surprised and therefore looked longer when the person searched for the toy in the incorrect location compared to the correct location. In contrast, the looking time for infants who experienced the unreliable looker did not differ for either search locations. These findings suggest that 16-month-old infants can differentially attribute beliefs about a toy's location based on the person's prior record of visual perception.
The theory of mind (ToM) impairment describes a difficulty someone would have with perspective taking. This is also sometimes referred to as mind-blindness. This means that individuals with a ToM impairment would have a hard time seeing things from any other perspective than their own. Individuals who experience a theory of mind deficit have difficulty determining the intentions of others, lack understanding of how their behavior affects others, and have a difficult time with social reciprocity. ToM deficits have been observed in people with autism spectrum disorders, people with schizophrenia, people with attention deficit disorder, persons under the influence of alcohol and narcotics, sleep-deprived persons, and persons who are experiencing severe emotional or physical pain.
In 1985 Simon Baron-Cohen, Alan M. Leslie and Uta Frith published research that suggested that children with autism do not employ a theory of mind, and suggested that children with autism have particular difficulties with tasks requiring the child to understand another person's beliefs. These difficulties persist when children are matched for verbal skills and have been taken as a key feature of autism.
Many individuals classified as having autism have severe difficulty assigning mental states to others, and they seem to lack theory of mind capabilities. Researchers who study the relationship between autism and theory of mind attempt to explain the connection in a variety of ways. One account assumes that theory of mind plays a role in the attribution of mental states to others and in childhood pretend play. According to Leslie, theory of mind is the capacity to mentally represent thoughts, beliefs, and desires, regardless of whether or not the circumstances involved are real. This might explain why individuals with autism show extreme deficits in both theory of mind and pretend play. However, Hobson proposes a social-affective justification, which suggests that a person with autism deficits in theory of mind result from a distortion in understanding and responding to emotions. He suggests that typically developing human beings, unlike individuals with autism, are born with a set of skills (such as social referencing ability) that later lets them comprehend and react to other people’s feelings. Other scholars emphasize that autism involves a specific developmental delay, so that children with the impairment vary in their deficiencies, because they experience difficulty in different stages of growth. Very early setbacks can alter proper advancement of joint-attention behaviors, which may lead to a failure to form a full theory of mind.
It has been speculated that ToM exists on a continuum as opposed to the traditional view of a concrete presence or absence. While some research has suggested that some autistic populations are unable to attribute mental states to others, recent evidence points to the possibility of coping mechanisms that facilitate a spectrum of mindful behavior. Tine et al. suggest that children with autism score substantially lower on measures of social theory of mind in comparison to children with Asperger syndrome.
Impairments in theory of mind, as well as other social-cognitive deficits are commonly found in people suffering from alcoholism due to the neurotoxic effects of alcohol on the brain, particularly the prefrontal cortex region of the brain.
Individuals in a current major depressive episode (MDD), a disorder characterized by social impairment, show deficits in theory of mind decoding. Theory of mind decoding is the ability to use information available in the immediate environment (e.g., facial expression, tone of voice, body posture) to accurately label the mental states of others . The opposite pattern, enhanced theory of mind, is observed in individuals vulnerable to depression, including those individuals with past MDD , dysphoric individuals, and individuals with a maternal history of MDD.
Research on theory of mind in autism led to the view that mentalizing abilities are subserved by dedicated mechanisms that can (in some cases) be impaired while general cognitive function remains largely intact. Neuroimaging research has supported this view, demonstrating specific brain regions consistently engaged during theory of mind tasks. Early PET research on theory of mind, using verbal and pictorial story comprehension tasks, identified a set of regions including the medial prefrontal cortex (mPFC), and area around posterior superior temporal sulcus (pSTS), and sometimes precuneus and amygdala/temporopolar cortex. Subsequently, research on the neural basis of theory of mind has diversified, with separate lines of research focused on the understanding of beliefs, intentions, and more complex properties of minds such as psychological traits.
Studies from Rebecca Saxe's lab at MIT, using a false belief versus false photograph task contrast aimed to isolate the mentalizing component of the false belief task, have very consistently found activation in mPFC, precuneus, and temporo-parietal junction (TPJ), right-lateralized. In particular, it has been proposed that the right TPJ (rTPJ) is selectively involved in representing the beliefs of others. However, some debate exists, as some scientists have noted that the same rTPJ region has been consistently activated during spatial reorienting of visual attention; Jean Decety from the University of Chicago and Jason Mitchell from Harvard have thus proposed that the rTPJ subserves a more general function involved in both false belief understanding and attentional reorienting, rather than a mechanism specialized for social cognition. However, it is possible that the observation of overlapping regions for representing beliefs and attentional reorienting may simply be due to adjacent but distinct neuronal populations that code for each. The resolution of typical fMRI studies may not be good enough to show that distinct/adjacent neuronal populations code for each of these processes. In a study following Decety and Mitchell, Saxe and colleagues used higher-resolution fMRI and showed that the peak of activation for attentional reorienting is approximately 6-10mm above the peak for representing beliefs. Further corroborating that differing populations of neurons may code for each process, they found no similarity in the patterning of fMRI response across space.
Functional imaging has also been used to study the detection of mental state information in Heider-Simmel-esque animations of moving geometric shapes, which typical humans automatically perceive as social interactions laden with intention and emotion. Three studies found remarkably similar patterns of activation during the perception of such animations versus a random or deterministic motion control: mPFC, pSTS, fusiform face area (FFA), and amygdala were selectively engaged during the ToM condition. Another study presented subjects with an animation of two dots moving with a parameterized degree of intentionality (quantifying the extent to which the dots chased each other), and found that pSTS activation correlated with this parameter.
A separate body of research has implicated the posterior superior temporal sulcus in the perception of intentionality in human action; this area is also involved in perceiving biological motion, including body, eye, mouth, and point-light display motion. One study found increased pSTS activation while watching a human lift his hand versus having his hand pushed up by a piston (intentional versus unintentional action). Several studies have found increased pSTS activation when subjects perceive a human action that is incongruent with the action expected from the actor’s context and inferred intention: for instance, a human performing a reach-to-grasp motion on empty space next to an object, versus grasping the object; a human shifting eye gaze toward empty space next to a checkerboard target versus shifting gaze toward the target; an unladen human turning on a light with his knee, versus turning on a light with his knee while carrying a pile of books; and a walking human pausing as he passes behind a bookshelf, versus walking at a constant speed. In these studies, actions in the "congruent" case have a straightforward goal, and are easy to explain in terms of the actor’s intention; the incongruent actions, on the other hand, require further explanation (why would someone twist empty space next to a gear?), and apparently demand more processing in the STS. Note that this region is distinct from the temporo-parietal area activated during false belief tasks. Also note that pSTS activation in most of the above studies was largely right-lateralized, following the general trend in neuroimaging studies of social cognition and perception: also right-lateralized are the TPJ activation during false belief tasks, the STS response to biological motion, and the FFA response to faces.
Neuropsychological evidence has provided support for neuroimaging results on the neural basis of theory of mind. A study with patients suffering from a lesion of the temporoparietal junction of the brain (between the temporal lobe and parietal lobe) reported that they have difficulty with some theory of mind tasks. This shows that theory of mind abilities are associated with specific parts of the human brain. However, the fact that the medial prefrontal cortex and temporoparietal junction are necessary for theory of mind tasks does not imply that these regions are specific to that function. TPJ and mPFC may subserve more general functions necessary for ToM.
Research by Vittorio Gallese, Luciano Fadiga and Giacomo Rizzolatti (reviewed in) has shown that some sensorimotor neurons, which are referred to as mirror neurons, first discovered in the premotor cortex of rhesus monkeys, may be involved in action understanding. Single-electrode recording revealed that these neurons fired when a monkey performed an action and when the monkey viewed another agent carrying out the same task. Similarly, fMRI studies with human participants have shown brain regions (assumed to contain mirror neurons) are active when one person sees another person's goal-directed action. These data have led some authors to suggest that mirror neurons may provide the basis for theory of mind in the brain, and to support simulation theory of mind reading (see above).
However, there is also evidence against the link between mirror neurons and theory of mind. First, macaque monkeys have mirror neurons but do not seem to have a 'human-like' capacity to understand theory of mind and belief. Second, fMRI studies of theory of mind typically report activation in the mPFC, temporal poles and TPJ or STS, but these brain areas are not part of the mirror neuron system. Some investigators, like developmental psychologist Andrew Meltzoff and neuroscientist Jean Decety, believe that mirror neurons merely facilitate learning through imitation and may provide a precursor to the development of ToM. Others, like philosopher Shaun Gallagher, suggest that mirror-neuron activation, on a number of counts, fails to meet the definition of simulation as proposed by the simulation theory of mindreading.
Several neuroimaging studies have looked at the neural basis theory of mind impairment in subjects with Asperger syndrome and high-functioning autism (HFA). The first PET study of theory of mind in autism (also the first neuroimaging study using a task-induced activation paradigm in autism) employed a story comprehension task, replicating a prior study in normal individuals. This study found displaced and diminished mPFC activation in subjects with autism. However, because the study used only six subjects with autism, and because the spatial resolution of PET imaging is relatively poor, these results should be considered preliminary.
A subsequent fMRI study scanned normally developing adults and adults with HFA while performing a "reading the mind in the eyes" task—viewing a photo of a human’s eyes and choosing which of two adjectives better describes the person’s mental state, versus a gender discrimination control. The authors found activity in orbitofrontal cortex, STS, and amygdala in normal subjects, and found no amygdala activation and abnormal STS activation in subjects with autism.
A more recent PET study looked at brain activity in individuals with HFA and Asperger syndrome while viewing Heider-Simmel animations (see above) versus a random motion control. In contrast to normally developing subjects, those with autism showed no STS or FFA activation, and significantly less mPFC and amygdala activation. Activity in extrastriate regions V3 and LO was identical across the two groups, suggesting intact lower-level visual processing in the subjects with autism. The study also reported significantly less functional connectivity between STS and V3 in the autism group. Note, however, that decreased temporal correlation between activity in STS and V3 would be expected simply from the lack of an evoked response in STS to intent-laden animations in subjects with autism; a more informative analysis would be to compute functional connectivity after regressing out evoked responses from all time series.
A subsequent study, using the incongruent/congruent gaze shift paradigm described above, found that in high-functioning adults with autism, posterior STS (pSTS) activation was undifferentiated while watching a human shift gaze toward a target and toward adjacent empty space. The lack of additional STS processing in the incongruent state may suggest that these subjects fail to form an expectation of what the actor should do given contextual information, or that information about the violation of this expectation doesn’t reach STS; both explanations involve an impairment in the ability to link eye gaze shifts with intentional explanations. This study also found a significant anticorrelation between STS activation in the incongruent-congruent contrast and social subscale score on the Autism Diagnostic Interview-Revised, but not scores on the other subscales.
In 2011, an fMRI study demonstrated that right temporoparietal junction (rTPJ) of higher-functioning adults with autism was not selectively activated more for mentalizing judgments when compared to physical judgments about self and other. rTPJ selectivity for mentalizing was also related to individual variation on clinical measures of social impairment; individuals whose rTPJ was increasingly more active for mentalizing compared to physical judgments were less socially impaired, while those who showed little to no difference in response to mentalizing or physical judgments were the most socially impaired. This evidence builds on work in typical development that suggests rTPJ is critical for representing mental state information, irrespective of whether it is about oneself or others. It also points to an explanation at the neural level for the pervasive mind-blindness difficulties in autism that are evident throughout the lifespan.
An open question is if other animals besides humans have a genetic endowment and social environment that allows them to acquire a theory of mind in the same way that human children do. This is a contentious issue because of the problem of inferring from animal behavior the existence of thinking, of the existence of a concept of self or self-awareness, or of particular thoughts. One difficulty with non-human studies of ToM is the lack of sufficient numbers of naturalistic observation, giving insight into what the evolutionary pressures might be on a species' development of theory of mind.
Non-human research still has a major place in this field, however, and is especially useful in illuminating which nonverbal behaviors signify components of theory of mind, and in pointing to possible stepping points in the evolution of what many claim to be a uniquely human aspect of social cognition. While it is difficult to study human-like theory of mind and mental states in species whose potential mental states we have an incomplete understanding, researchers can focus on simpler components of more complex capabilities. For example, many researchers focus on animals' understanding of intention, gaze, perspective, or knowledge (or rather, what another being has seen). Call and Tomasello's study that looked at understanding of intention in orangutans, chimpanzees and children showed that all three species understood the difference between accidental and intentional acts. Part of the difficulty in this line of research is that observed phenomena can often be explained as simple stimulus-response learning, as it is in the nature of any theorizers of mind to have to extrapolate internal mental states from observable behavior. Recently, most non-human theory of mind research has focused on monkeys and great apes, who are of most interest in the study of the evolution of human social cognition. Other studies relevant to attributions theory of mind have been conducted using plovers and dogs, and have shown preliminary evidence of understanding attention—one precursor of theory of mind—in others.
There has been some controversy over the interpretation of evidence purporting to show theory of mind ability—or inability—in animals. Two examples serve as demonstration: first, Povinelli et al. (1990) presented chimpanzees with the choice of two experimenters from which to request food: one who had seen where food was hidden, and one who, by virtue of one of a variety of mechanisms (having a bucket or bag over his head; a blindfold over his eyes; or being turned away from the baiting) does not know, and can only guess. They found that the animals failed in most cases to differentially request food from the "knower". By contrast, Hare, Call, and Tomasello (2001) found that subordinate chimpanzees were able to use the knowledge state of dominant rival chimpanzees to determine which container of hidden food they approached. William Field and Sue Savage-Rumbaugh have no doubt that bonobos have developed ToM and cite their communications with a well known captive bonobo, Kanzi, as evidence.
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