Theory of mind
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, intentions, and perspectives that are different from one's own. Deficits can occur in people with autism spectrum disorders, schizophrenia, attention deficit hyperactivity disorder, cocaine addiction, as well as alcoholics who have suffered brain damage due to alcohol's neurotoxicity. Although philosophical approaches to this exist, the theory of mind as such is distinct from the philosophy of mind.
Theory of mind is a theory insofar as the mind is the only thing being directly observed. The presumption that others have a mind is termed a theory of mind because each human can only intuit the existence of their own mind through introspection, and no one has direct access to the mind of another. It is typically assumed that others have minds analogous to one's own, and this assumption is based on the reciprocal, social interaction, as observed in joint attention, the functional use of language, and the understanding of others' emotions and actions. Having 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 primates including humans, that requires social and other experience over many years for its full development. Different people may develop more, or less, effective theory of mind. Empathy is a related concept, meaning the recognition and understanding of 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 empathetic 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 Guy 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 through established relations.
Philosophical and psychological rootsEdit
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. It is also closely related to person perception and attribution theory from social psychology.
The intuitive assumption that others are minded is an apparent tendency we all share. We anthropomorphize non-human animals, inanimate objects, and even natural phenomena. 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 (RFT) 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 the development of this ability in human ontogeny and phylogeny, has identified several behavioral precursors to 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 with stickers as baited. 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 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.
There is evidence to believe that the development of theory of mind is closely intertwined with language development in humans. One meta-analysis (Milligan, Astington, & Dack, 2007) showed a moderate to strong correlation (r = 0.43) between performance on theory of mind and language tasks. One might argue that this relationship is due solely to the fact that both language and theory of mind seem to begin to develop substantially around the same time in children (between ages 2–5). However, many other abilities develop during this same time period as well, and do not produce such high correlations with one another nor with theory of mind. There must be something else going on to explain the relationship between theory of mind and language.
Miller (2006) posed a few possible explanations for this relationship. One idea was that the extent of verbal communication and conversation involving children in a family could explain theory of mind development. The belief is that this type of language exposure could help introduce a child to the different mental states and perspectives of others. This has been suggested empirically by findings indicating that participation in family discussion predict scores on theory of mind tasks (Ruffman, Slade, & Crowe, 2002), as well as findings showing that deaf children who have hearing parents and may not be able to communicate with their parents much during early years of development tend to score lower on theory of mind tasks (Wolfe, Want, & Siegal, 2002).
Another explanation of the relationship between language and theory of mind development has to do with a child's understanding of mental state words such as "think" and "believe". Since a mental state is not something that one can observe from behavior, children must learn the meanings of words denoting mental states from verbal explanations alone, requiring knowledge of the syntactic rules, semantic systems, and pragmatics of a language (Miller, 2006). Studies have shown that understanding of these mental state words predicts theory of mind in four-year-olds (Moore, Pure, & Furrow, 1990).
Lastly, a third hypothesis is that the ability to distinguish a whole sentence ("Jimmy thinks the world is flat") from its embedded complement ("the world is flat") and understand that one can be true while the other can be false is related to theory of mind development. Recognizing these sentential complements as being independent of one another is a relatively complex syntactic skill and has been shown to be related to increased scores on theory of mind tasks in children (de Villiers & Pyers, 2002).
Whether children younger than 3 or 4 years old may have any 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 into her basket, and then leaves the room. While she is out of the room, Anne takes the marble from the basket and puts it into 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 Sally 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 able to pass the tasks from 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, defined as: "the inclination to see events that have already happened as being more predictable than they were before they took place." 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 "Unexpected contents", 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 "Smarties" exist 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, either a location or identity change exists. 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 has looked at innovative ways at capturing preverbal 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 of 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 persons 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 difficult time seeing phenomena 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 nonverbal learning disorder, 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 suggested that children with autism do not employ Theory of Mind, and suggested that autistic children 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 autistic 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 some autistic individuals show extreme deficits in both theory of mind and pretend play. However, Hobson proposes a social-affective justification, which suggests that with an autistic person, deficits in theory of mind result from a distortion in understanding and responding to emotions. He suggests that typically developing human beings, unlike autistic individuals, 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 autistic children 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 discrete 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 autistic children score substantially lower on measures of social theory of mind in comparison to children diagnosed with Asperger syndrome.
Individuals with the diagnosis of schizophrenia can show deficits in theory of mind. Mirjam Sprong and colleagues investigated the impairment by examining 29 different studies, with a total of over 1500 participants. This meta-analysis showed significant and stable deficit of theory of mind in people with schizophrenia. They performed poorly on false-belief tasks, which test the ability to understand that others can hold false beliefs about events in the world, and also on intention-inference tasks, which assess the ability to infer a character's intention from reading a short story. Schizophrenia patients with negative symptoms, such as lack of emotion, motivation, or speech, have the most impairment in theory of mind and are unable to represent the mental states of themselves and of others. Paranoid schizophrenic patients also perform poorly because they have difficulty accurately interpreting others' intentions. The meta-analysis additionally showed that IQ, gender, and age of the participants does not significantly affect the performance of theory of mind tasks.
Current research suggests that impairment in theory of mind negatively affects clinical insight, the patient's awareness of their mental illness. Insight requires theory of mind—a patient must be able to adopt a third-person perspective and see the self as others do. A patient with good insight would be able to accurately self-represent, by comparing oneself with others and by viewing oneself from the perspective of others. Insight allows a patient to recognize and react appropriately to his symptoms; however, a patient who lacks insight would not realize that he has a mental illness, because of his inability to accurately self-represent. Therapies that teach patients perspective-taking and self-reflection skills can improve abilities in reading social cues and taking the perspective of another person.
The majority of the current literature supports the argument that the theory of mind deficit is a stable trait-characteristic rather than a state-characteristic of schizophrenia. The meta-analysis conducted by Sprong et al. showed that patients in remission still had impairment in theory of mind. The results indicate that the deficit is not merely a consequence of the active phase of schizophrenia.
Schizophrenic patients' deficit in theory of mind impairs their daily interactions with others. An example of a disrupted interaction is one between a schizophrenic parent and a child. Theory of mind is particularly important for parents, who must understand the thoughts and behaviors of their children and react accordingly. Dysfunctional parenting is associated with deficits in the first-order theory of mind, the ability to understand another person's thoughts, and the second-order theory of mind, the ability to infer what one person thinks about another person's thoughts. Compared with healthy mothers, mothers with schizophrenia are found to be more remote, quiet, self-absorbed, insensitive, unresponsive, and to have fewer satisfying interactions with their children. They also tend to misinterpret their children's emotional cues, and often misunderstand neutral faces as negative. Activities such as role-playing and individual or group-based sessions are effective interventions that help the parents improve on perspective-taking and theory of mind. Although there is a strong association between theory of mind deficit and parental role dysfunction, future studies could strengthen the relationship by possibly establishing a causal role of theory of mind on parenting abilities.
Alcohol use disordersEdit
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.
Depression and dysphoriaEdit
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.
Specific language impairmentEdit
Children diagnosed with specific language impairment (SLI) exhibit much lower scores on reading and writing sections of standardized tests, yet have a normal nonverbal IQ. These language deficits can be any specific deficits in lexical semantics, syntax, or pragmatics, or a combination of multiple problems. They often exhibit poorer social skills than normally developing children, and seem to have problems decoding beliefs in others. A recent meta-analysis confirmed that children with SLI have substantially lower scores on Theory of Mind tasks compared to typically developing children (Nilsson & Lopez, 2015). This strengthens the claim that language development is related to Theory of Mind.
In typically developing humansEdit
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. PET research on theory of mind, using verbal and pictorial story comprehension tasks, has identified a set of brain 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 at isolating 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. Examples would be: 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 then apparently would 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 regarding the neural basis of theory of mind. Studies with patients suffering from a lesion of the frontal lobes and 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, as well as 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) that 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.
However, in a recent paper, Keren Haroush and Ziv Williams outlined the case for a group of neurons in primates' brains that uniquely predicted the choice selection of their interacting partner. These primates' neurons, located in the anterior cingulate cortex of rhesus monkeys, were observed using single-unit recording while the monkeys played a variant of the iterative prisoner's dilemma game. By identifying cells that represent the yet unknown intentions of a game partner, Haroush & Williams' study supports the idea that theory of mind may be a fundamental and generalized process, and suggests that anterior cingulate cortex neurons may potentially act to complement the function of mirror neurons during social interchange.
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) replicated a prior study in normal individuals, which employed a story-comprehension task. 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 they watched a human shift gaze toward a target and then 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 feedback 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 the right temporoparietal junction (rTPJ) of higher-functioning adults with autism was not more selectively activated 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.
The brain regions associated with theory of mind include the superior temporal gyrus (STS), the temporoparietal junction (TPJ), the medial prefrontal cortex (MPFC), the precuneus, and the amygdala. The reduced activity in the MPFC of individuals with schizophrenia is associated with the Theory of mind deficit and may explain impairments in social function among people with schizophrenia. Increased neural activity in MPFC is related to better perspective-taking, emotion management, and increased social functioning. Disrupted brain activities in areas related to theory of mind may increase social stress or disinterest in social interaction, and contribute to the social dysfunction associated with schizophrenia.
Group member average scores of theory of mind abilities, measured with the Reading the Mind in the Eyes test (RME), are suggested as drivers of successful group performance. In particular, high group average scores on the RME are shown to be correlated with the collective intelligence factor c defined as a group's ability to perform a wide range of mental tasks, a group intelligence measure similar to the g factor for general individual intelligence. RME is a ToM test for adults that shows sufficient test-retest reliability and constantly differentiates control groups from individuals with functional autism or Asperger syndrome. It is one of the most widely accepted and well-validated tests for ToM abilities within adults.
The evolutionary origin of theory of mind remains obscure. While many theories make claims about its role in the development of human language and social cognition few of them specify in detail any evolutionary neurophysiological precursors. A recent theory claims that ToM has its roots in two defensive reactions, namely immobilization stress and tonic immobility, which are implicated in the handling of stressful encounters and also figure prominently in mammalian childrearing practices (Tsoukalas, 2017). Their combined effect seems capable of producing many of the hallmarks of theory of mind, e.g., eye-contact, gaze-following, inhibitory control and intentional attributions.
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 or of particular thoughts, or the existence of a concept of self or self-awareness, consciousness and qualia. One difficulty with non-human studies of ToM is the lack of sufficient numbers of naturalistic observations, 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 whom 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.
In a 2016 experiment, ravens Corvus corax were shown to take into account visual access of unseen conspecifics. It is suspected that "ravens can generalize from their own perceptual experience to infer the possibility of being seen".
A 2016 study published by evolutionary anthropologist Christopher Krupenye brings new light to the existence of ToM, and particularly false beliefs, in non-human primates.
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