Hence, it has been proposed that REM sleep stimulates the development of the visual system during infancy, informs the visual cortex about eye movements, and facilitates proper responses to environmental stimuli. Many of these functions are performed via its ponto-geniculo-occipital PGO waves. Not surprisingly, the incidence of REM sleep diminishes after the visual system has matured sufficiently Roffwarg et al.
This theory has found support in studies of people with REM sleep behavior disorder RBD , an affliction in which the sleeping person tries to enact his dreams. It has been found that when they try to enact goal-oriented dreams they seem to adjust their eye and body movements in accordance with the dream action Leclair-Visonneau et al. REM sleep has a powerful influence on the early life of children. Research has shown that newborns have no discrete sleep cycles and spend most of their sleeping time in a state resembling REM sleep.
An issue that is seldom addressed in connection with ToM is when human infants acquire this complex ability. This is a highly pertinent question as human infants spend most of the day sleeping. How can we understand this peculiar situation? Since then his claim has received considerable support see Franklin and Zyphur Examples of such behaviors are exploration in the rat, defensive maneuvers in the rabbit, and stalking in the cat notice the connection to predator-prey relationships.
The acquisition of these behaviors is subserved by a special type of brain activity, theta rhythms. Similar phenomena have also been observed in humans. Emde and Koenig , in their observational study of newborns, found that early smiling was almost exclusively connected to a particular organismic state, that of REM sleep and REM sleep drowsiness.
Although this smiling response is far removed from the fully developed social smile, the authors speculated that they probably share a common neuropsychological foundation. This reflexive smiling can be seen as a ontogenetic adaptation whose purpose is to facilitate nursing and help establish the parent-child bond Bjorklund Zborowski and McNamara have proposed that REM sleep functions to promote nighttime physiological synchrony and daytime psychological attachment between mother and child and that it continues to have similar functions in the mature organism by promoting sexual mating and pair bond formation.
The daytime search behaviors of the child are then guided by this internal working model and periodically activated in association with a min daydreaming rhythm. Antii Revonsuo has claimed that the main function of REM sleep is to process upsetting daily experiences and in so doing improve performance of various real-life tasks. Dreams accomplish this by rehearsing threat avoidance skills in the simulated environment of dream mentation.
The ultimate goal of this rehearsal is to increase the adaptive capacity of the organism. This function is, supposedly, an endowment of our evolutionary past in which such dangers abounded in the environment and their successful evasion was a daily necessity. Taken together, these studies can help us understand a rather puzzling ethological observation.
Juveniles of several primate species, including humans, continue to sleep with their mother even though they have become fully detached from her during the day Bowlby : — Since this behavior has been evolutionarily conserved in so many species, there is a distinct possibility that it performs a vital function. What could this function be? ToM could be such a skill Fonagy and Target The most impressive evidence of REM sleeps importance for ToM, however, comes from studies of children with autism. As is well-known, a hallmark of this pathology is the lack of, or improper functioning, of ToM.
Buckley et al.
Likewise, other sleep disorders common to autistic children also seem to be related to perturbations of REM sleep Devnani and Hedge Finally, Tessier et al. Thus, the evidence suggests that a relative dysfunction of REM sleep may underlie the pathogenesis of autism. Another class of neurochemicals implicated in childhood development are the endogenous opioids.
These substances have a special relationship to aversive experiences and are released in response to various physical e. Upon release, they help the organism withstand its challenge by conferring a degree of analgesia and also promote more adaptive responses by curbing the negative consequences of an overactive stress response. Since opioids also produce a sense of euphoria they additionally have a rewarding effect, especially if coupled with successful coping—for example removing the source of injury or finding social consolation Nelson and Panksepp ; Lieberman ; Valentino and van Bockstaele The combined effect of analgesia and euphoria creates a motivational system critical for early survival.
Whenever the infant is threatened or in pain its secretion of endogenous opioids rise Hindmarsh et al. This is so because by responding appropriately, usually through a combination of physical contact and feeding e. This is done partly through tactile stimulation, which is known to release endogenous opioids, and partly by milk infusion, which is a rich source of endogenous opioids Nelson and Panksepp ; Zanardo et al. If the parental response is not prompt and appropriate, however, the child experiences separation distress which further exacerbates its agonizing state Bowlby ; Lohaus et al.
Thus, for the child, successful coping reinforces contact seeking and relationship building with its caregivers. Several scholars have pointed to the evolutionary significance of the endogenous opioids, a role in many ways similar to that of oxytocin. Studies have shown that the daytime thinking of infants and young children is dominated by a special kind of brain activity, theta rhythms. As children grow up, however, theta rhythms are gradually crowded out of the brain by other types of brainwaves Orekhova et al.
One of the last vestiges of theta rhythms in the adult organism is REM sleep. REM sleep abounds in both cortical and hippocampal theta rhythms Cantero et al. In adults, when present, theta rhythms have been associated with pleasurable feelings, drowsiness, creativity and meditative states Schacter ; Gruzeler ; Jensen et al.
Theta rhythms are mainly produced by the hippocampus and some parts of the cerebral cortex Cantero et al. In experimental animals, this type of brain activity is connected to either active exploration or to motionless alertness. There seems to be a division of frequencies in this regard. Interestingly, motionless alertness seems to be predicated on cholinergic neurotransmission and consistently evoked by the threatening presence of a predator and accompanied by visual vigilance Kramis et al. Motionless alertness is common in human infants. Perhaps the most dramatic example of this is the phenomenon of staring spells Carmant et al.
As every parent knows, infants have a tendency to become highly absorbed by visual stimuli, especially faces and their eyes, and can stare at them for prolonged periods of time. This behavior can be so frequent and marked that it is often misjudged for epileptic seizures leading alarmed parents to rush to the nearest emergency room for medical assistance. The outcome of these visits is usually benign as the behavior is non-pathological. As suggested above, there seems to be a special relationship between eye movements and altered states of mind. This relationship has wide-ranging consequences.
For example, sustained attention coupled with monotonous stimulation can trigger various dissociative phenomena , from everyday mind wandering Wegner ; Biever and Karinch and ordinary drowsiness Thiffault and Bergeron ; Sallinen et al. With a hypothesis on the origins of ToM in place, we next turn our attention to its evidentiary basis. Is there any evidence, direct and indirect, in support of its various claims? I believe there is and that it is sufficiently robust to point the way from a mere analogy to an evolutionary homology.
In what follows, I will present this evidence as well as address some unattended issues. The present hypothesis claims that immobilization reactions whether TI or IS during early childhood facilitate eye contact and gaze following. Is there any evidence for this in human children? To begin with, there is plenty of anecdotal evidence. Human children like to be carried, hugged, and cuddled and all these behaviors can, actually if counterintuitively, be seen as various forms of manual restraint and immobilization.
The importance of such physical contact has become part of present-day folk psychology and also incorporated in many nursing best practices Montagu ; Ardiel and Rankin A reason for this may be that older children have more developed sympathetic nervous systems and, hence, are more easily aroused and stressed than infants and toddlers Slotkin et al.
When it comes to studies directly testing the facilitating effect of immobilization on eye contact and gaze following the evidence is more scant. There are many possible reasons for this. One reason is epistemological. For various reasons, studies of this kind have not been deemed relevant or necessary. Another reason for this scarcity is ethical. Forcefully immobilizing human infants is, for most intents and purposes, unacceptable to both parents and researchers. Despite this, however, there are a number of studies that offer tentative support of this relationship. In a qualitative study, Svendsen et al.
They identified three broad response patterns: protest, escape, and endurance.
- Social cognition?
- Genuine Risk: Thoroughbred Legends?
- Theory of mind.;
Closer scrutiny revealed, among other things, that children in the two first categories showed signs of fear and panic during the procedure and generally avoided eye contact with the nursing staff, while those in the endurance category showed signs of paralysis and dissociation but did not avoid eye contact with the nursing staff. Camras et al. They found that arm restraint consistently lead to an increase of various facial expressions, irrespective of cultural background.
Finally, Porter et al. They found that infants that had been handled and immobilized as a result of common nursing activities displayed higher physical arousal and more facial expressions following a heel stick a classical noxious stimuli than those who had not been subjected to this treatment. Although the above studies are heterogeneous methodologically, and their results preliminary, their findings lend support to the present hypothesis.
It is possible that immobilization, whether due to constitutional factors i. Using a metaphor we could say that by being immobilized infants wear their hearts on their faces. One possible way this came to pass is by the innervation of the human face by the vagus nerve, a cholinergic nerve which is activated by the stimulation of pressure receptors on the body and has both inhibitory and expressive qualities Field and Diego ; Porges If the present hypothesis has any merit to it, it should show some correspondence to how children have been handled over the ages.
Although a thorough review of the matter falls outside the scope of this presentation, it is fair to say that infant immobilization has figured prominently in the history of human childrearing practices, whether in hunter-gatherer, agrarian or modern societies Lipton et al. The ways in which infants have been immobilized in order to facilitate their care and the work of the adults are numerous: holding in the bosom, swaddling , carrying in a sling, putting in a cradleboard etc.
Although some of these practices have fallen out of favor today, it is possible that they played an important role in human evolution. Looking closer at swaddling, perhaps the most emblematic of all immobilization practices, further confirmatory evidence emerges. The classical study by Lipton et al. Newer studies have confirmed these results and also found that swaddling, especially in preterm infants, leads to improved neuromuscular development, less physiologic distress, better motor organization, and more self-regulatory ability Van Sleuwen et al.
Theory of mind: mechanisms, methods, and new directions
It should be mentioned, though, that swaddling has also been found to have certain adverse effects. For example, it may increase the risk of developing hip dysplasia Van Sleuwen et al. Any theory that purports to explain its origins should have something to say about it. How does defensive immobilization contribute to this delicate task? As it turns out it, its contribution is fundamental. Despite the appearance of inactivity, a captured animal retains a high degree of visual vigilance.
This is a purposeful behavior. If the victim can gather such information successfully, it has a better chance to escape and survive. And one of the best sources of such information is the eye movements of the predator. This fact, attested in the literature on predator-prey relationships, adds considerable depth to the present argument as it directly addresses the issue of intentionality. And it points to a plausible evolutionary scenario: the intentionality detector inherent in TI and IS was, through successive stages of mammalian evolution, transferred to human cognition, and became the founding stone on which ToM was built.
But is there any human evidence, beyond the ethological studies cited, to support such a contention? Several investigations have pointed to a possible relationship between ToM and threat perception. Connolly et al. As pointed out in the introduction, this area is centrally implicated in the control of both face recognition and mindreading. In other words, threat perception and ToM are subserved by the same neural circuitry. The connection of the superior temporal sulcus to tonic immobility is strengthened by other findings as well.
Schultz et al. Of course, such a discriminatory ability is of paramount importance in predator-prey relationships where it is imperative, at every moment, to know if the enemy is moving towards or away from oneself. Similarly, studies have shown that the superior colliculus , another structure involved in the control of ToM, is implicated in the visual detection and recognition of threatening stimuli such as snakes and faces with emotional expressions Maior et al.
This overlap in function is most pronounced during infancy, a finding also in line with the present hypothesis as TI and IS are also more pronounced in immature individuals.
Interestingly, the superior colliculus has also been implicated in the control of both the eye movements and the circadian timing of REM sleep Doricchi et al. Impressive evidence also comes from studies of the orienting response , an emergency reaction to unexpected stimuli. Here, several studies have pointed to a rather unexpected finding: the orienting response in humans, though not a social behavior per se, is directly related to the faculty of ToM.
The two reactions are actually subserved by the same neural circuits Corbetta et al. This makes perfect sense in light of the present hypothesis as the orienting response is a well-known defensive maneuver, the first in line of the mammalian defensive cascade. Much of this threat perception and intention detection is done with the help of the eyes, through eye contact and gaze following.
For this reason, other than in aggressive encounters and predatory-prey relations, direct eye contact is a relatively rare occurrence in the animal kingdom. Whenever it occurs it is necessarily accompanied by appeasement displays Morris : —; Dixon Humans are a blatant exception to this near-rule. How did humans develop a knack for this behavior, most strikingly evidenced by the almost compulsive eye-contact seeking of infants? A possibility is that a hypertrophy in the eye contact seeking and gaze-following components of TI and IS, along with an enlargement of the prefrontal cortex, made this behavioral change possible more on this later.
However, not all humans like eye contact to the same degree. Autistic people, in particular, have inborn difficulties with eye contact, difficulties that go well beyond personal idiosyncrasies and cultural conventions. For such people eye contact is a highly distracting and distressing event, one which they habitually avoid Baron-Cohen et al. More than that, recent research has shown that, like in many mammalian species, autistic persons experience eye contact as a direct threat Dalton et al.
It is as if the neural circuitry that makes eye contact non-threatening, and even attractive, for the majority of people is defective or absent in the case of autistic children. Tonic immobility is the main inhibitory reflex of the mammalian defensive cascade and is predicated on cholinergic neurotransmission instead of aminergic neurotransmission Thompson ; Klemm ; Kozlowska et al. Are there any such traces? Considerable support comes from studies that have looked at the relationship of ToM to higher order functions. Several studies have shown that inhibitory control , the ability to suppress or moderate prepotent responses, is intimately related to the faculty of ToM.
Carlson and Moses , for example, showed that performance in tasks requiring a novel response in the face of a conflicting and prepotent response, as well as tasks requiring the delay of a prepotent response, were significantly related to ToM. Chasiotis et al. Taken together, these findings show that inhibitory control is a crucial enabling factor in the development and function of ToM.
Support also comes from studies of the relationship between temperament and cognitive development. It is well-known that temperamental differences have a direct bearing on parent-child interactions and can even influence the attachment process Thomas and Chess ; Kagan One theory that has made specific predictions about this relationship, and garnered considerable support, is the emotional reactivity hypothesis Hare Wellman et al.
Similarly, Mink et al. A remarkable fact is that some domesticated animals seem to have cognitive abilities that rival, and occasionally even surpass, those of primates. Dogs, for example, are unusually skilled at reading human social and communicative behavior: they readily follow pointing gestures, seek eye contact, gaze follow, and even show rudimentary forms of ToM Miklosi et al. These findings, which have perplexed scientists for a long time, are now beginning to be understood within a unified framework.
Domestication induces a number of critical changes in the biology and ethology of animals Wilkins et al. Studies have shown that this change is mediated by a downregulation in the activity of the sympathetic nervous system, the system which controls the fight-or-flight reflex. Domesticated foxes, for example, exhibit reduced adrenal gland size and have a three- to fivefold reduction in both basal and stress-induced blood cortisol levels Osadschuk ; Trut et al. Another way of understanding the prosocial changes brought about by domestication is by realizing that selective breading for tameness tends to produce neotenous changes in the offspring, both in the sense of growth retardation and in the sense of pedomorphic features.
These two ways of understanding the effects of domestication are, furthermore, intrinsically related as immature individuals are by default less aggressive than their grown-up counterparts. The enlarged window of socialization during infancy in domesticated animals is, hence, to a large extent predicated on the prolonged immaturity of their hypothalamic-pituitary-adrenal system which prevents them from resorting to fearful reactivity as often, and as forcefully, as their wild-type kin.
The animals were kept captive, lived in enclosed spaces, and subjected to manual restraint, all proprietary triggers of defensive immobilization reactions. After all, the essence of tameness is that an animal readily yields to its master. This tipping of the scales in favor of passive defenses as opposed to aggressive defenses may actually have enabled the evolution of the devotional tie between dogs and humans.
According to several scholars this curbing of the aggressive drive, a kind of self-domestication , also played an important role in human evolution Morris ; Eccles ; Hare ; Hare et al. Biological, environmental, and cultural factors may have jointly contributed to a critical reduction in sympathetic nervous system activity during early childhood, thus enlarging the window of socialization, and enabling distinctly human forms of learning and cooperation to evolve.
The present article has highlighted two possible, and interrelated, ways through which this pacification and enculturation process may have proceeded. One of the points that I have tried to convey throughout this article is that the default mode of infants is that of a motionless and calm alertness , a mode also common to defensively immobilized animals and hypnotized subjects cf.
Peiper ; Krojanker ; Vrugt and Pederson ; Yoshida et al. In particular, it is a prerequisite for the emergence of ToM. It follows from this that disturbances in this default mode can lead to serious developmental problems. A good case in point is offered, once again, by autism.
It has been known for quite some time that autistic children show sensorimotor deficits, for example movement disorders, much earlier than they show cognitive and social deficits Kanner ; P. Teitelbaum et al. This rigidity and tension is indicative of a postural dysregulation. This, however, is a difficult task for many autistic people. Several studies have shown that they suffer from a general over-activation of their sympathetic nervous system and a corresponding under-activation of their parasympathetic nervous system Kushki et al.
This imbalance between sympathetic and parasympathetic tone, between neural excitation and inhibition, could actually help explain some of their developmental problems Rubenstein and Merzenich But how is this imbalance expressed on the neurophysiological level? One possibility is that autistic children suffer from a deficit in cholinergic neurotransmission , as this type of neurotransmission has been shown to play a central role in the regulation of muscle tone. Gall et al. Takakusaki et al. Similarly, in humans the pedunculopontine nucleus is responsible for gait and postural control Morita et al.
Importantly, these brainstem nuclei, and adjacent areas, have also been implicated in the control of TI and REM sleep Lai and Siegel ; Klemm ; Dergacheva et al. Several studies have pointed to cholinergic abnormalities in the cerebral cortex and basal forebrain of autistic people. These abnormalities cover the whole gamut and range from pathological involvement of cholinergic nuclei to altered expression of acetylcholine receptors Perry et al. In most cases, these changes amount to a significant reduction in the functionality of the brains cholinergic system. Interestingly, these cholinergic abnormalities also seem to extend to the function of the cerebellum, a recent focus of attention in studies of autism.
Lee et al. Not surprisingly, correcting these cholinergic deficits is generally beneficial for autism. Similarly, Langley et al. The difficulties of autistic children in entering a restful body position may also be explained by a deficit in oxytocinergic neurotransmission. As described previously oxytocin release is triggered by immobilization, has an anxiolytic effect and inhibits avoidance behaviors during stressful encounters.
Studies in both animals and humans have shown that this anxiolytic and inhibitory effect is achieved by a downregulation of the sympathetic nervous system and a simultaneous maintenance of cholinergic vagus nerve activity Grewen and Light ; Kenkel et al. Hence, a relative lack of this neuropeptide could tip the balance in favor of sympathetic over-activation. In line with this, studies have shown that autistic children suffer from low levels of plasma oxytocin Modahl et al.
In this article, I have presented a novel hypothesis on the origin of ToM. According to this hypothesis, ToM is evolutionarily descended from two closely related defensive reactions, tonic immobility TI and immobilization stress IS , and in particular from their intentionality detecting component.
TI, which is predicated on cholinergic neurotransmission, is triggered by a combination of fearful stimulation, manual restrain, and postural inversion of an animal i. Immobilization stress, which is predicated on oxytocinergic neurotransmission, is instead triggered by the forceful immobilization of an animal, and leads to the suppression of avoidance behaviors, confers analgesia, increases attention to the eye region, and facilitates face processing. I believe that the neurophysiology and neuropsychology of these two defensive reactions, closely related as they are, was passed on to humans and became a constitutive part of infantile behavior and a prerequisite of normal cognitive development.
In particular, they seem to have facilitated face-to-face interactions, intentional attributions, and inhibitory control. This evolutionary endowment, however, is so well-camouflaged in modern humans that it very easy to miss. This hypothesis forces us to reconceptualize the standard narrative on parent-child interactions. Parent-child interactions are usually described in highly amicable terms: love, devotion, symbiosis, trust etc.
These qualities are, further, believed to lay the foundation for a stable social bond which nourishes the child through its long period of helplessness and also function as a prototype for many later relations and group formations. While this narrative is not necessarily wrong, its overly romanticized view of parent-child interactions may obscure important facts from our consideration, facts that may have an important bearing on the evolutionary origins of ToM. The beginnings of parent-child interactions may, actually, have been far removed from their present state and only reached it through a long series of, mostly counterintuitive, evolutionary, and developmental steps.
Mary Ainsworth : 79, 83 and John Bowlby : , for example, noted that fear of strangers and a general sense of alarm both trigger and facilitate attachment behavior in children. Similarly, Stephen Porges has claimed that many prosocial behaviors, including parent-child attachment, are based on a substrate of inherited defense mechanisms e. Throughout this text, we have found references to REM sleep, often unexpectedly so. This raises the question as to what kind of relationship REM sleep has to the central tenet of our thesis, namely that ToM evolved from a set of defensive reactions.
An answer to this question is offered by a recent study which claims that REM sleep evolved out of the tonic immobility reflex Tsoukalas This claim is based on the fact that REM sleep shows striking similarities—on both neurophysiological, phenomenological, and behavioral accounts—to this ancient defense mechanism. Hence, both REM sleep and TI are characterized by EEG desynchronization, cholinergic neurotransmission, brainstem control, generalized inhibition, loss of muscle tone, hippocampal theta waves, eye movements, and thermoregulatory changes.
This theory complements the present hypothesis in a crucial way and the interested reader is, therefore, advised to consult it independently. During REM sleep acetylcholine deactivates part of the prefrontal cortex leaving only the ventromedial prefrontal cortex active to moderate the activity of the amygdala, an intervention that is thought to reprocess previous affective experiences in a therapeutic direction.
Hartmann ; Walker and van der Helm This effect is not only limited to the sleeping period but, importantly, has been shown to have a residual effect on subsequent wakefulness as well van der Helm et al. Given the large amount of REM sleep in infants relative to adults, this residual effect must be massive and could help explain the motionless and calm alertness and staring spells so typical of this age.
This ranquilizing effect of REM sleep, which protects the organism from excessive sympathetic reactivity accumulated during the day, is unavailable to autistic children due to their intrinsic deficit of REM sleep. Theory of mind is an important part of human forethought. Not surprisingly, it is partly controlled by the prefrontal cortex Fletcher et al. From an evolutionary point of view, however, it might have been the other way around. The emergence and consolidation of ToM may have paved the way for the evolution of the prefrontal cortex, the brains high seat of planning and executive control.
There are many ways to conceptualize the prefrontal cortex and its varied functions Teffer and Semendeferi ; Hoffman A particularly helpful one is to see it as a mainly inhibitory influence on the rest of the brains functions. The suppression of prepotent responses and filtering of distractions is a necessary prerequisite for the generation of sustained attention, a distinguishing human trait. Where does this inhibitory power come from? Trying to find an answer, and given all that we have said before, it is difficult not to think of the two reflexes that make up the cornerstones of this thesis, namely TI and IS, which both have well-defined inhibitory properties e.
From an evolutionary point of view, they may have provided the inhibitory impetus necessary for the development of the human prefrontal cortex. So how did this evolution look like? Below I offer a rough sketch. For reasons of parsimony, I will focus my attention on the TI reflex. A comparable argument, however, can be made for the evolutionary contribution of the IS reflex. Oxytocin, too, seems to have had a finger in the game of hominid brain evolution Carter In reptiles, amphibians and birds TI is a ubiquitous and well-formed reflex.
But with the transition to mammals, it almost disappears. How can we explain such a swift, phylogenetically speaking, disappearance? What happened to it? The answer favored here is that the reorganization of the mammalian brain gradually absorbed this primitive reflex and made it an integral part of its structure and function. But what, more precisely, prompted the unique configuration of the human prefrontal cortex?
After all, many mammals have a prefrontal cortex but very few of them exhibit human-like behaviors. The answer is extreme neoteny. As several authors have shown, such infantilization was advantageous and eventually lead, through compensatory changes in brain architecture, to the emergence of distinctly human traits and human culture.
The effect of neoteny was probably three-partite. Firstly, the progressive infantilization of the species placed humans under the prolonged influence of various mammalian reflexes related to immobilization, reflexes which in other animals are only operative for a short time after birth. Two examples of such reflexes are TI and IS. Both these reflexes are prevalent during infancy, suppress aggressive behaviors and avoidance maneuvers during stressful encounters, and include an intentionality detector which works through the monitoring of eye movements Prestrude ; Hennig ; McCarthy et al.
Secondly, neoteny also resulted in a temperamental shift leading to a more contemplative and cooperative mood so typical of human beings. Thirdly, neoteny enabled humans to lie down in the supine position, a position which is anatomically difficult to achieve for many other mammals Morris ; Michel and Goodwin When other mammals do exhibit it, it is usually as a sign of defeat and submission Grant ; Grant and Mackintosh ; Dixon The supine position afforded human infants the opportunity to engage in face-to-face interactions with their parents, a fact that enabled them to develop cognitive and prosocial abilities out of reach for other mammalian species Takeshita et al.
Is there any empirical support for this, admittedly speculative, claim? As always, finding direct evidence for evolutionary claims is a difficult task. There is, however, plenty of indirect evidence. A piece of evidence comes from studies of the functional specialization of the prefrontal cortex. The interpretation favored here is that this is a remnant of the evolutionary history of the prefrontal cortex, which has its beginnings in the inhibitory control and visual vigilance inherent in defensive immobilization.
Magnetic resonance studies have shown that this area is implicated in the management of uncertainty , becoming intensely activated whenever subjects experience uncertainty Volz et al. This activation of the prefrontal cortex could also encode hope, a higher order expectation positively correlated to uncertainty Chew and Ho In any case, both these emotions could easily be ascribed to the residual influence of TI or IS; for an animal captured by a predator uncertainty could not be higher and hope more vital.
If we look at the dorsolateral prefrontal cortex, the phylogenetically and ontogenetically most recent addition to the human brain, the plot thickens even more. In this brain region, which includes area 8, we find one of the control mechanisms of ToM see Introduction. Furthermore, studies have shown that this brain region is activated by threat-induced vigilance. The same study showed that people who are more inhibited than others have a higher tonic activity in the right-posterior dorsolateral prefrontal cortex. Not surprisingly, dysfunction of this area has been shown to correlate with difficulties in complex problem solving Shackman et al.
Interestingly, recent studies have uncovered the possibility of cholinergic neurotransmission in this area Yang et al. Finally, several studies have shown that ToM predates the development of other prefrontal faculties. For example, both Hughes and Ensor and Austin et al. More decisively, Morales et al. Although these studies are preliminary, and the interpretation of their findings is difficult, the available results make good sense from the point of view of our hypothesis.
The study by Rousseau et al. Pending further investigation we can make some well-grounded speculations. Many other primitive reflexes are present around or shortly after birth e. As the brain develops, over the first years of life connections to higher centers are strengthened and increasingly take over the functions of these primitive reflexes. In this way, early survival patterns are gradually tempered and superseded by more mature patterns of response Zafeiriou ; Goddard This probably also happens with neonatal TI. During development the subcortical circuit of ToM, which is faster and informationally encapsulated, becomes coupled to a cortical circuit, which is slower and more context and task sensitive, and this maturation process eventually leads to the prefrontal cortex assuming considerable control of this mental faculty Fletcher et al.
A proof of this comes from the fact that, in the relatively few mammals that show full-fledged TI, the neocortex seems to antagonize its initiation in mature individuals Teschke et al. In addition to this neuroanatomical integration, there is probably also a change in the character of the mental representations involved. According to Annette Karmiloff-Smith , an important aspect of childhood development is the gradual translation of knowledge into increasingly higher level formats: from implicit to explicit and from procedural to declarative.
This process, however, does not obliterate the original formats but instead results in the existence of multiple representations of the same or similar knowledge in different formats. The increasing sophistication of the ToM faculty with age, and its cortical preponderance, bespeaks such a redescription process. Thanks to the seminal works of Walter Canon and Hans Selye , , every psychology student knows about the importance of the fight-or-flight reflex. Unfortunately, a comparable development never occurred with regards to tonic immobility.
Even today, very few people now about TI, and even fewer know of its relevance for human health and well-being. In the pages of this article, I have tried to open up a window into its fascinating world by showing how it might have contributed to the evolution ToM. Other scholars have also emphasized the importance of this behavioral disposition and, in closing this article, I would like to briefly highlight some of their thoughts.
According to Stephen Porges , defensive immobilization was through successive stages of mammalian evolution, co-opted by the cortex to support various forms of social engagement including those of parent-child interactions. Mammals have a natural tendency to be on-guard when they meet other individuals—whether of their own or different species—and can easily be pushed into defensive maneuvers and even fight-or-flight.
This tendency, however, needs to be curbed in order for certain necessary prosocial behaviors to occur. In humans, these defensive reactions can be inhibited if a cognitive appraisal signals that the environment is safe. In such a case, the brain releases of endogenous opiates and oxytocin which pacify the limbic system and produce analgesia and euphoria.
This quiescence —a condition reminiscent of the hypnotic trance—is a prerequisite for successful parent-child attachment, nursing behaviors and pair bond formation cf. Peiper ; Krojanker ; Vrugt and Pederson Brian Hare has claimed that the evolutionary selection of animals with less reactive temperaments supported the development of sophisticated social-cognitive skills in several species, including humans.
Evolution may thus have favored the enlargement of areas related to passive avoidance and appeasement, like the septal area and prefrontal cortex, while simultaneously attenuating the function of areas related to rage and aggression, like the amygdala cf. Eccles : —, As mentioned previously, TI is antithetical to the fight-and-flight reflex and as such abolishes panic reactions and aggressive behavior.
This feat is achieved through a direct inhibition of the amygdala Leite-Panissi et al. Finally, we ought to mention Herbert Benson and his work on the relaxation response Benson et al. Although Benson never traced the phylogenetic origins of this response to defensive immobilization he increased both public and scholarly awareness of its importance and practical utilization.
This perspective is not functionalist as most other theories in the field; it does not claim to have identified a new function of ToM. This idea, though it might strike some as outlandish, has partly been entertained before. Baron-Cohen , while formulating his theory of an eye-direction-detector EDD , discussed various gaze-following behaviors in lower animals, including those exhibited by prey animals; however, he did not elaborate on the evolutionary importance of TI or give it any theoretical weight in his subsequent work on ToM.
In general, the importance of this primitive reflex has, hitherto, not been acknowledged in discussions of ToM. This response is the first-line of defense in a long chain of defensive behaviors. It is usually a reaction to a sudden noise but can also be elicited by visual or proprioceptive stimuli. Upon such stimulation, the animal abruptly ceases its ongoing activity and the eyes and ears scan the environment for threats. It has been speculated  that Theory of Mind 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.
Learn what Theory of Mind is and why it matters for overall development.
Generally, children with more advanced theory of mind abilities display more advanced social skills, greater adaptability to new situations, and greater cooperation with others. As a result, these children are typically well-liked. Peer-mediated interventions PMI are a school-based treatment approach for children and adolescents with autism spectrum disorder in which peers are trained to be role models in order to promote social behavior.
Laghi et al. Selecting children with advanced theory of mind skills who use them in prosocial ways will theoretically make the program more effective. While the results indicated that analyzing the social uses of theory of mind of possible candidates for a PMI program is invaluable, it may not be a good predictor of a candidate's performance as a role model. 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 participants.
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.
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 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. 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. Individuals in a current major depressive episode , a disorder characterized by social impairment, show deficits in theory of mind decoding.
The opposite pattern, enhanced theory of mind, is observed in individuals vulnerable to depression, including those individuals with past major depressive disorder MDD , [ citation needed ] dysphoric individuals,  and individuals with a maternal history of MDD. 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. 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 DLD have substantially lower scores on theory of mind tasks compared to typically developing children. 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. 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.
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. 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 mm 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 Theory of Mind condition. 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.
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.
The incongruent actions, on the other hand, require further explanation why would someone twist empty space next to a gear? Note that this region is distinct from the temporo-parietal area activated during false belief tasks. 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. 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.
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. 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.
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. 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. 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.
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.
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. 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. 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 , 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.
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.
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.
RME is a Theory of Mind test for adults  that shows sufficient test-retest reliability  and constantly differentiates control groups from individuals with functional autism or Asperger syndrome. 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 Theory of Mind 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, An open question is whether 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.
One difficulty with non-human studies of theory of mind 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. A 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.
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. They found that the animals failed in most cases to differentially request food from the "knower". By contrast, Hare, Call, and Tomasello found that subordinate chimpanzees were able to use the knowledge state of dominant rival chimpanzees to determine which container of hidden food they approached. In a experiment, ravens Corvus corax were shown to take into account visual access of unseen conspecifics.
The researchers argued that "ravens can generalize from their own perceptual experience to infer the possibility of being seen". A study published by evolutionary anthropologist Christopher Krupenye brings new light to the existence of Theory of Mind, and particularly false beliefs, in non-human primates. From Wikipedia, the free encyclopedia. Ability to attribute mental states to oneself and others. Main article: Collective intelligence. See also: Animal consciousness and Theory of mind in animals.
Behavioral and Brain Sciences. Developmental cognitive neuroscience of Theory of Mind. Ed: J. J Stud Alcohol Drugs. Blackwell, pp. Intention in the structure of action and interaction. Rovee-Collier Eds. Smith, Eds. Theories of theories of mind. Cambridge: Cambridge University Press. Journal of Deaf Studies and Deaf Education. Developmental Science. The development of mental processing. Nesselroade, J. Methods in the study of life-span human development: Issues and answers. Overton Ed.
Volume 1 of the Handbook of life-span development pp. Hoboken, New Jersey: Wiley. Relational frame theory: A post-Skinnerian account of human language and cognition. Derived Relational Responding: Applications for learners with autism and other developmental disabilities. Oakland, California: New Harbinger. The self and perspective-taking: Contributions and applications from modern behavioral science. Simulation and self-knowledge: a defence of the theory-theory. The Intentional Stance. Cambridge: MIT Press. Association for Contextual Behavioral Science. And what is known about the mental processes that underlie such understanding?
Not only would social perceivers without a theory of mind be utterly lost in a simple payment interaction; without a theory of mind, there would probably be no such things as cashiers, credit cards, and payment Tomasello, Plain and simple, humans need to understand minds in order to engage in the kinds of complex interactions that social communities small and large require.
And it is these complex social interactions that have given rise, in human cultural evolution, to houses, cities, and nations; to books, money, and computers; to education, law, and science. The list of social interactions that rely deeply on theory of mind is long; here are a few highlights. Another way of appreciating the enormous impact that theory of mind has on social interactions is to study what happens when the capacity is severely limited, as in the case of autism Tager-Flusberg, Scientific research has accumulated a good deal of knowledge in the past few decades, and here is a synopsis of what we know.
Figure 1 shows some of the most important tools, organized in a way that reflects the complexity of involved processes: from simple and automatic on the bottom to complex and deliberate on the top. This organization also reflects development—from tools that infants master within the first 6—12 months to tools they need to acquire over the next 3—5 years. Strikingly, the organization also reflects evolution: monkeys have available the tools on the bottom; chimpanzees have available the tools at the second level; but only humans master the remaining tools above.
The agent category allows humans to identify those moving objects in the world that can act on their own. The process of recognizing goals builds on this agent category, because agents are characteristically directed toward goal objects, which means they seek out, track, and often physically contact said objects.
What it means to recognize goals, therefore, is to see the systematic and predictable relationship between a particular agent pursuing a particular object across various circumstances. Through learning to recognize the many ways by which agents pursue goals, humans learn to pick out behaviors that are intentional. The concept of intentionality is more sophisticated than the goal concept. For one thing, human perceivers recognize that some behaviors can be unintentional even if they were goal-directed—such as when you unintentionally make a fool of yourself even though you had the earnest goal of impressing your date.
To act intentionally you need, aside from a goal, the right kinds of beliefs about how to achieve the goal. A subtle, automatic form of imitation is called mimicry , and when people mutually mimic one another they can reach a state of synchrony. Have you ever noticed when two people in conversation take on similar gestures, body positions, even tone of voice? Some research findings suggest that synchronizing is made possible by brain mechanisms that tightly link perceptual information with motor information when I see you move your arm, my arm-moving program is activated.
In humans, however, things are a bit more complex. Automatic empathy builds on imitation and synchrony in a clever way.