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 do not significantly affect the performance of theory of mind tasks. 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 can accurately self-represent, by comparing himself with others and by viewing himself from the perspective of others. insight allows a patient to recognize and react appropriately to his symptoms. a patient who lacks insight does 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. research indicates that 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. this indicates that the deficit is not merely a consequence of the active phase of schizophrenia. schizophrenic patients' deficit in theory of mind impairs their interactions with others. 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 in 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. there is a strong association between theory of mind deficit and parental role dysfunction. alcohol use disorders impairments in theory of mind, as well as other social-cognitive deficits, are commonly found in people who have alcohol use disorders, due to the neurotoxic effects of alcohol on the brain, particularly the prefrontal cortex. depression and dysphoria individuals in a major depressive episode, 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 major depressive disorder (mdd), dysphoric individuals, and individuals with a maternal history of mdd. developmental language disorder children diagnosed with developmental language disorder (dld) 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. such children 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 dld have substantially lower scores on theory of mind tasks compared to typically developing children. this strengthens the claim that language development is related to theory of mind. brain mechanisms in neurotypical people 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 supports this view, demonstrating specific brain regions are consistently engaged during theory of mind tasks. pet research on theory of mind, using verbal and pictorial story comprehension tasks, identifies 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. research on the neural basis of theory of mind has diversified, with separate lines of research focusing 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 consistently found activation in mpfc, precuneus, and temporoparietal junction (tpj), right-lateralized. in particular, it has been proposed that the right tpj (rtpj) is selectively involved in representing the beliefs of others. some debate exists, as the same rtpj region is consistently activated during spatial reorienting of visual attention; jean decety from the university of chicago and jason mitchell from harvard thus propose 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. using single-cell recordings in the human dorsomedial prefrontal cortex (dmpfc), researchers at mgh identified neurons that encode information about others' beliefs, which were distinct from self beliefs, across different scenarios in a false-belief task. they further showed high specificity between cells based on the content of the others' beliefs and were able to accurately predict whether these beliefs were true or false. these findings suggest a prominent role of distinct neuronal populations in the dmpfc in theory of mmind complemented by the tpj and psts. functional imaging also illuminates 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 theory of mind 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 implicates 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 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 apparently demand more processing in the sts. this region is distinct from the temporoparietal area activated during false belief tasks. 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 supports neuroimaging results regarding the neural basis of theory of mind. studies with patients with a lesion of the frontal lobes and the temporoparietal junction of the brain (between the temporal lobe and parietal lobe) report 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 theory of mind. research by vittorio gallese, luciano fadiga, and giacomo rizzolatti shows that some sensorimotor neurons, referred to as mirror neurons and 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 performing the same action. fmri studies with human participants show brain regions (assumed to contain mirror neurons) that are active when one person sees another person's goal-directed action. these data 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. there is also evidence against a 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 those 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 theory of mind. 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. in autism several neuroimaging studies have looked at the neural basis for 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 neurotypical 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 less 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