Le bâillement, du réflexe à la pathologie
Le bâillement : de l'éthologie à la médecine clinique
Le bâillement : phylogenèse, éthologie, nosogénie
 Le bâillement : un comportement universel
La parakinésie brachiale oscitante
Yawning: its cycle, its role
Warum gähnen wir ?
Fetal yawning assessed by 3D and 4D sonography
Le bâillement foetal
Le bâillement, du réflexe à la pathologie
Le bâillement : de l'éthologie à la médecine clinique
Le bâillement : phylogenèse, éthologie, nosogénie
 Le bâillement : un comportement universel
La parakinésie brachiale oscitante
Yawning: its cycle, its role
Warum gähnen wir ?
Fetal yawning assessed by 3D and 4D sonography
Le bâillement foetal

mystery of yawning 



mise à jour du
12 mars 2021
Dev Sci.
Contagious itching is heightened in children
with autism spectrum disorders
Helt MS, de Marchena AB, Schineller ME,
Kirk AI, Scheub RJ, Sorensen TM.


 Tous les articles sur la contagion du bâillement
All articles about contagious yawning
The authors tested susceptibility to contagious itching, laughter, and yawning in 55 children with autism spectrum disorder (ASD), ages 8&endash;14, and 106 typically develop- ing (TD) children, ages 5&endash;14. Children with ASD were less likely to yawn or laugh con- tagiously compared with TD peers, but showed increased susceptibility to contagious itching, under naturalistic conditions. Contagious yawning and laughter were posi- tively correlated with emotional empathy in the TD group. In contrast, contagious itching showed no relationship to empathy, and was positively correlated with autism symptom severity in the ASD group. The authors explore the implications of these findings in terms of psychological theories about ASD.
Les auteurs ont testé la sensibilité à la contagion des démangeaisons, du rire et du bâillement chez 55 enfants atteints de troubles du spectre autistique (TSA), âgés de 8 à 14 ans, et 106 enfants en développement normal (TD), âgés de 5 à 14 ans. Les enfants atteints de TSA étaient moins susceptibles de bâiller ou de rire de façon contagieuse que leurs pairs TD, mais montraient une susceptibilité accrue à la contagion des démangeaisons, dans des conditions naturalles. Les bâillements contagieux et les rires étaient positivement corrélés à l'empathie émotionnelle dans le groupe TD. En revanche, la contagion des démangeaisons n'a montré aucune relation avec l'empathie mais était positivement corrélées à la gravité des symptômes de l'autisme dans le groupe TSA. Les auteurs explorent les implications de ces résultats en termes de théories psychologiques sur les TSA.
Autism spectrum disorder (ASD) is characterized by restricted and repetitive behaviors and pervasive difficulties in social cogni- tion and communication (American Psychiatric Association, 2013), as well as atypical development of empathy (Baron-Cohen & Wheelwright, 2004; Schulte-Ru_ther et al., 2014). Theories of em- bodied cognition speculate that the means by which we develop empathy is by mentally simulating the experiences of others, as we embody their actions. One type of simulation that occurs early in development is demonstrated by the phenomenon of contagion&emdash; the transfer of behaviors (facial expression, tone of voice, body posture) from one person to another without conscious attribution (Dimberg, Thunberg, & Elmehed, 2000; Meltzoff & Moore, 1989); for example, when a newborn baby cries at the sound of another baby crying (Simner, 1971). Sharing motor&emdash;and thus, neural&emdash;rep- resentations with social partners may be especially important early in development, potentially providing an embodied basis for the
cquisition of speech sounds, identifying people, and novel tool use (Meltzoff, 1993) as well as broader, more complex, aspects of so- cial and empathic development (Nummenmaa, Hirvonen, Parkkola, & Hietanen, 2008; Preston & De Waal, 2002). In other words, em- bodying the actions of others may foster interpersonal connections by allowing the body to implicitly feel and assign meaning to the ac- tions of others, even before the onset of language. Investigating the extent to which individuals with ASD experience common forms of contagion may shed light on developmental processes that unfold differently in autistic development.
1.1 | Contagion and empathy
Although definitions vary between fields and theorists, most re- searchers would likely agree that empathy is a multilevel construct, involving both emotional processes (e.g., automatically forming a link between oneself and another's inner state) and cognitive processes (e.g., being able to take another person's perspective). Certain ac- tions, such as laughing, yawning, and itching, are "contagious," mean- ing that they often result in automatic mimicry and thus propagate through a group (Hatfield, Cacioppo, & Rapson, 1993). For example, hearing a laugh produces laughter in approximately half of listeners and smiles in approximately 90% of listeners (Provine, 1992). Seeing (Helt, Fein, & Vargas, 2019; Provine & Hamernik, 1986) or hearing a yawn (Helt et al., 2019; Massen, Church, & Gallup, 2015) elicits yawning in others between 30% and 60% of the time. The behaviors that are most likely to be contagious are those that signify the inner states of others (Hatfield et al., 1993). Contagious yawning, laughing, and itching are easily observable signs of resonance between two individuals, with one person taking on the physiological and inner state of the other. Contagion may reflect the emotional component of empathy in that it results in the observer being brought closer to the inner state of the target without necessarily evoking the cogni- tive component of empathy (e.g., newborns presumably are unable to identify that another baby is the source of the emotion when cry- ing contagiously, and certainly cannot understand why). This con- cept is referred to across the literature as "emotional contagion" (Preston & de Waal, 2002), "affective empathy" (Davis, 1983), and "emotional empathy" (Blair, 2005).
Several behavioral studies have suggested an indirect associa- tion between contagious yawning and cognitive components of em- pathy. For example, susceptibility to contagious yawning is positively related to performance on self-face recognition and theory-of-mind tasks, and negatively related to schizotypal traits (Platek, Critton, Myers, & Gallup, 2003). Norscia and Palagi (2011) reported conta- gious yawning to be greatest in response to kin, then friends, then acquaintances, and lastly strangers, a pattern that is true for other empathic behaviors (Preston & De Waal, 2002). However, Massen et al. (2015) point out that this differential response in contagion may have been due to individuals' tendency to pay greater attention to kin than to strangers, and reported that participants were no more likely to yawn contagiously to a member of their political "in" versus "out" group. In addition, the majority of fMRI studies have reported an association between a participants self-reported desire to yawn while viewing others yawn in the scanner (importantly, participants are unable to yawn in an fMRI study and so these are measures of the neural correlates of the urge to yawn as opposed to true yawn conta- gion) and areas of the brain associated with mirror neurons and self- other processing (Arnott, Singhal, & Goodale, 2009; Haker, Kawohl, Herwig, & Ro_ssler, 2013; Nahab, Hattori, Saad, & Hallett, 2009; Platek, Mohamed, & Gallup, 2005), although Schu_rmann et al. (2005) reported no mirror neuron involvement.
At the same time, correlational studies that have probed direct links between participants' susceptibility to contagious yawning and their global empathy traits have, more often than not, failed to find them (see Massen & Gallup, 2017, for a comprehensive review). Although positive relationships between contagious yawn suscepti- bility and direct measures of empathy have been observed (Arnott et al., 2009), several studies have reported non-significant links be- tween susceptibility to yawn contagion and scores on various empa- thy measures (Bartholomew & Cirulli, 2014; Gottfried, Lacinova_, & S_iru_c_ek, 2015; Haker & Ro_ssler, 2009). We know of no studies that have previously investigated a link between contagious laughter and empathy. All of the above suggest the need for more comprehen- sive research into the link between contagion and different forms of empathy. For the purposes of the current study, the most important point may be that individuals with, or at-risk for, clinical disorders affecting empathy, such as schizophrenia, callous and unemo- tional traits, and psychopathic traits, show reduced spontaneous susceptibility to both contagious yawning (Haker & Ro_ssler, 2009; Rundle, Vaughn, & Stanford, 2015) and contagious laughter (Haker & Ro_ssler, 2009; O'Nions et al., 2017).
1.2 | Contagion in ASD
The question of whether contagion tends to be "weak, intact, or heightened" in individuals with ASD is a matter of some de- bate (Minio-Paluello, Lombardo, Chakrabarti, Wheelwright, & Baron-Cohen, 2009; Smith, 2009). Support for the "weak" theory includes the fact that contagious yawning in individuals with ASD is reduced across a variety of contexts, including: ex- posure to examiner yawns during a live interaction (Helt, Eigsti, Snyder, & Fein, 2010), watching videos of strangers yawning (Helt et al., 2019; Senju et al., 2007), and listening to yawns (Giganti & Esposito Ziello, 2009; Helt et al., 2019). Susceptibility to contagious laughter is also reduced in participants with ASD (Helt et al., 2019). These findings are consistent with a broader body of work suggest- ing that many individuals with ASD show reduced congruent emo- tional responses (Bacon, Fein, Morris, Waterhouse, & Allen, 1998; Hadjikhani et al., 2009; Scambler, Hepburn, Rutherford, Wehner, & Rogers, 2007) and reduced spontaneous mimicry (McIntosh, Reichmann-Decker, Winkielman, & Wilbarger, 2006; Stel, van den Heuvel, & Smeets, 2008).
On the other hand, multiple studies have reported intact, or even heightened, emotional response to others among individu- als with ASD. For example, Press, Richardson, and Bird (2010) re- ported intact automatic mimicry of facial actions among individuals with ASD. Similarly, Hadjikhani et al. (2014) reported no differences between participants with and without ASD in brain activation of pain sharing regions when participants were shown faces of oth- ers in pain. Magne_e, De Gelder, Van Engeland, and Kemner (2007) presented stimuli of emotional expressions, as well as emotional ex- pressions paired with voices to adults with ASD, and found that, in comparison to controls with a history of typical development, adults with ASD showed intact in response to the faces paired with voices, and heightened automatic facial mimicry (as measured by electromy- ography) in response to happy and fearful faces. Finally, pupillary contagion (an important mechanism for transfer of affective and arousal levels between individuals; Prochazkova & Kret, 2017) in in- dividuals with ASD is comparable to that of controls when observing pictures of emotional faces, despite less spontaneous attention to- ward the eye region (Galazka et al., 2019). A pupillometric study of infants at genetic risk for ASD showed that high-risk infants exhib- ited larger pupil dilations when observing emotional face stimuli than controls (Wagner, Luyster, Tager-Flusberg, & Nelson, 2016).
A possible explanation for these disparate findings comes from a growing body of research suggesting that contagion among indi- viduals with ASD is context dependent, and can be increased under certain contexts relevant to social motivation and attention. First, yawning and laughter contagion appear to be comparable to controls when participants with ASD are explicitly cued to attend the eyes of the target (Helt et al., 2019; Senju et al., 2009; Usui et al., 2013). Critically, children with ASD also yawn and laugh contagiously to the same extent as typical peers when the yawning/laughing target is their own parent (Helt et al., 2019), suggesting a role for both so- cial attention and social affiliation. Although not a direct measure of contagion, highly verbal individuals with ASD show intact neu- ral responses when viewing the faces of others in pain (Hadjikhani et al., 2014). Thus, it appears that individuals with ASD demonstrate typical or near typical levels contagion when either they are explic- itly cued to attend to the relevant features (in the studies above, the eyes) of the target, or when they are spontaneously more attentive to a target they perceive as more salient (i.e., a parent or a person in pain).
When looking at individual differences, spontaneous contagion to unfamiliar others appears to best predict autism symptom severity. Autism symptom severity is inversely related to the spontaneous (but not voluntary) mimicry of the facial expressions of others (McIntosh et al., 2006). Similarly, both yawning (Helt et al., 2010, 2019) and laughing (Helt et al., 2019) contagion are inversely correlated with ASD severity, such that children with ASD who are more likely to yawn/laugh contagiously have fewer and/or less severe ASD symp- toms. Thus, probing the conditions under which these phenomena occur without explicit cueing or other attentional manipulations may lead to a richer understanding of core impairments in social reciproc- ity in this population.
1.3 | Eye gaze and contagion
One of the most consistent findings across individuals with ASD is the tendency for reduced attention to the eyes of others (Moriuchi, Klin, & Jones, 2017). Behavioral studies have shown that children with ASD often demonstrate typical performance on simple tasks involving understanding and imitating signals from the hands, such as gestures and reaching, and that adults with ASD show automatic mimicry of the hand movements of others (Bird, Leighton, Press, & Heyes, 2007; Smith & Bryson, 1998; Southgate & Hamilton, 2008). In contrast, studies examining performance on automatic facial imitation tasks have produced mixed results (Loveland et al., 1994; McIntosh et al., 2006; but also Magne_e et al., 2007; Press et al., 2010), suggesting the possibility that this group may perform differently on tasks in which the hands or body are being observed rather than the face. The question of whether individuals with ASD demonstrate less spontaneous contagion to unfamiliar others under all conditions or only under conditions in which the signal is transmitted from the eyes has yet to be inves- tigated behaviorally.
1.4 | Contagious itching
In addition to contagious yawning and laughter, itching by con- tagion represents one of only a few motor programs that can be involuntarily induced by external (seeing or hearing it) or in- ternal (thinking about it) stimuli (Provine, 2012). Between 43% and 82% of people experience contagious itch when exposed to stimuli of others scratching, establishing that contagious itch occurs as commonly as contagious yawning and laughter (Papoiu, Wang, Coghill, Chan, & Yosipovitch, 2011). Contagious itch, like contagious yawning (Anderson, Myowa-Yamakoshi, & Matsuzawa, 2004) and laughter (Davila-Ross, Allcock, Thomas, & Bard, 2011), has even been demonstrated in non-human pri- mates (Feneran et al., 2013), pointing to its evolutionary history among social species. Contagious itch involves the perception of a target's behaviors, and automatic mimicry of the target's be- haviors, followed by a response that brings the observer's inner state closer to that of the target's. However, a direct relationship between empathy and contagious itch has yet to be directly inves- tigated. Indeed, contagious itch has actually been shown to occur more frequently in controls with high levels of neuroticism (the tendency to experience negative emotion; Holle, Warne, Seth, Critchley, & Ward, 2012).
Evidence from both behavioral studies (Papoiu et al., 2011; Ward, Burckhardt, & Holle, 2013) and neuroimaging (Holle et al., 2012) of adults with a typical developmental history sug- gests that contagious itching is, like laughter (Scott, Lavan, Chen, & McGettigan, 2014) and yawning (Deputte, 1994), associated with an inner state. Holle et al. (2012) found that the thalamus, primary somatosensory cortex, prefrontal (BA 44) and premotor cortex, and anterior insula were all activated while participants watched vid- eos of other people scratching. They argued that a feeling-based rather than an action-based system has a more central role in con- tagious itch due to the fact that the insula, a region associated with the affective components of bodily sensations, showed the more sustained activity during contagious itch (importantly, participants are unable to scratch in an fMRI scanner, thus these are measures of the neural correlates of a contagious itchy sensation rather than true behavioral itching contagion). Further supporting this idea, Papoiu et al. (2011) and Ward et al. (2013) have demonstrated that observers scratch body areas that differ in location from those they observed (i.e., matching the feeling of being itchy rather than the action of the target).
Critically for the present study, unlike contagious yawning (Provine, 1989) and contagious laughter (Surakka & Hietanen, 1998), itching does not rely on visual attention to the eyes or require any mimicry of the facial region. The current study will explore the relationship between contagious laughter, yawning, and itch and individ- ual differences in empathy and autism symptoms.
Children with ASD were less likely to yawn and laugh contagiously compared with their TD peers, but more likely to itch contagiously when presented with videos of others performing these actions. Contagious yawning and laughter were positively correlated with emotional empathy in controls, whereas contagious itching showed no relationship to emotional empathy. In the ASD group, contagious yawning and laughing did not correlate significantly with autism symptoms, whereas contagious itching did, such that greater ASD symptom severity was associated with more susceptibility to con- tagious itch. Furthermore, across groups, contagious yawning and contagious laughter were positively correlated with one another, but neither was significantly correlated with contagious itching, suggest- ing the possibility that contagious yawning and laughing may reflect or rely upon a shared construct (perhaps the tendency to look at the eyes of others) that is distinct from contagious itching.
These results are consistent with previous research suggesting that individuals with ASD do spontaneously observe and take on the in- ternal states of unfamiliar others around them under some conditions (Hadjikhani et al., 2014; Helt et al., 2019; Magne_e et al., 2007; Press et al., 2010). Whereas previous research has shown that the tendency to do so under naturalistic conditions is inversely related to ASD symp- tom severity (in the cases of yawning, laughter, and facial mimicry; Helt et al., 2010; Helt et al., 2019; McIntosh et al., 2006), the current study shows that under some circumstances (in the case of itching) the ten- dency to engage in spontaneous contagious behavior may be positively associated with the ASD phenotype. Below we discuss implications of our findings for current autism theories, followed by several accounts of why contagious itching may be heightened in ASD.
One category of psychological theories of autism (theories of re- duced social resonance), consistent with accounts of weakened conta- gion, argues that reductions in social motivation and affiliation toward others are at the core of autism symptoms, and thus social partners often fail to engage the attention and interest of individuals with ASD (Chevallier, Kohls, Troiani, Brodkin, & Schultz, 2012; Fein, Pennington, Markowitz, Braverman, & Waterhouse, 1986; Kanner, 1944; Uddin et al., 2013). One specific type of reduced social resonance theory is the "mirror neuron" theory of autism (Ramachandran & Oberman, 2006; Williams, Whiten, Suddendorf, & Perrett, 2001), which asserts that in- nate abnormalities in the mirror neuron system of individuals with ASD compromise their ability to spontaneously experience a correspon- dence between themselves and others, both in terms of observable physical states and inner (mental) states.
A second category of psychological theories of autism (theories of overarousal and reduced social attention), consistent with accounts of heightened contagion, hypothesizes that many stimuli are experienced by people on the spectrum as painfully intense, leading to selective attention and avoidance of social input (Kinsbourne, 2011; Markram & Markram, 2010; Smith, 2009). According to these theories, it is not that individuals with ASD do not find others salient from birth, it is that they instead find it overwhelming to interact with others, and so they defensively turn their attention inward as a compensatory mechanism to regulate their arousal levels. Indeed, although the relevant statisti- cal contrasts are not reported, a longitudinal study of infants at risk for ASD suggests that, as newborns, those who later develop ASD (and who, for most of their development, attend far less to social stimuli) may in fact attend to social stimuli more relative to those who do not develop ASD as newborns (Jones & Klin, 2013).
Each possibility suggests distinct implications for the neural bases of reduced contagion among individuals with ASD, and for theories about the underpinnings of ASD symptoms. The former im- plies a failure to develop a typical neural system that is requisite for social engagement. The latter implies a social neural network that is intact, but that the consequences of engaging with others are too overwhelming and painful, and so attention is withdrawn from the social world as a compensatory mechanism.
On the one hand, the results of the present study do not shed direct light on whether an individual with autism is only less likely to "catch" the behaviors and emotions of others because he/she is less likely to attend to the actions of others (i.e., when contagion is re- duced in ASD it is secondary to reduced social attention), or whether individuals with autism are less susceptible to contagious stimuli even when they are attending (i.e., when contagion is reduced in ASD it is driven by a deficit in social resonance).
On the other hand, the findings of increased contagious itch among participants with ASD have several theoretical implications. First, these findings seem to be in direct opposition to the ("bro- ken") mirror neuron theory of autism, as contagious itch activates the mirror neuron system (Holle et al., 2012) and demonstrates that individuals with ASD have the ability to spontaneously experience a correspondence between themselves and others, under some cir- cumstances. In our view, the fact that individuals with ASD show heightened contagious itching suggests that they do not have in- nate disruption to the mirror neuron system, as has been previously proposed (Ramachandran & Oberman, 2006; Rizzolatti & Fabbri- Destro, 2010; Williams et al., 2001), and is, rather, more consistent with the notion that they have had reduced developmental experi- ence registering many types of co-action with others and so their mirror networks are not as efficient and automatic across as wide a range of circumstances. Individuals with ASD show markedly re- duced attention to the faces, and particularly the eyes, of others beginning at 6 months of age (Osterling, Dawson, & Munson, 2002), which may lead to reduced efficiency in the processing of facial sig- nals. In other words, at least some neural mechanisms underlying interpersonal engagement appear to be intact, and in some cases even heightened, but chronically underused, in children with ASD.
Second, we argue that any enhanced response in the realm of perceiving and mimicking the behavior of another is more difficult to reconcile with theories of autism that posit that all signals of unfamil- iar others are not salient for individuals with ASD. The present study contributes to a growing body of literature making clear that some signals about the inner states of others are quite salient and automat- ically co-experienced by children with ASD. In addition, the possible explanations for our results (outlined below: avoidance of eye region information, sensory abnormalities that produce heightened response to seeing itch stimuli, heightened emotional empathy in general, or heightened personal distress only) would each contribute to making the infant's world more painful and increasing the infant's desire to turn attention inward or to objects as a self-regulation strategy, thus, we interpret these findings as more consistent with (overarousal) the- ories postulating "heightened" contagion individuals with ASD.
Third, Vivanti and Rogers (2014) argue that three distinct aspects of social learning are critical for advancing knowledge in the area of autism and the mirror neuron system: (a) the mechanisms that allow for the implicit mapping of and learning from others' behavior, (b) the motivation to attend to, and model, conspecifics, and (c) the flexible and selective use of social learning. The present results&emdash;in other words, the finding that even one form of behavior of a stranger is im- plicitly mapped and enacted by individuals with ASD&emdash;are consistent with the notion that the first of these mechanisms is intact among in- dividuals with ASD and that the second of these mechanisms should be the subject of further study.
In the results of the current study, some forms of contagion (yawning and laughing) appeared "weak" in participants with ASD compared to TD controls, and another (itch) appeared "heightened." We speculate that these results are best viewed in terms of Vivanti and Roger's (2014) second criteria, the motivation to attend, and offer several possible explanations for this pattern of results.
4.1 | Reduced visual attention to eyes
The first possible explanation for the observation of heightened spontaneous contagion in the case of itch, and reduced contagion in the cases yawning and laughter in the present sample, is that in- dividuals with ASD are more likely to show spontaneous contagion to unfamiliar others if the signal is not transmitted via the eyes. It is pos- sible that contagion that is elicited without the potential confound of requiring direct eye gaze from the participant with ASD reveals an underlying tendency for heightened contagion in this popula- tion. It may even be this initially heightened arousal in response to the emotions of others, which overwhelms the young child, caus- ing them to avoid direct eye gaze as a strategy for self-regulation (as when we turn our own eyes away from something unpleasant; Dalton et al., 2005). Indeed, individuals with ASD experience both elevated arousal and amygdala activity (Kaartinen et al., 2012; Kyllia_inen & Hietanen, 2006; Kyllia_inen et al., 2012; Stagg, Davis, & Heaton, 2013) in response to direct eye gaze, over and above that of their TD peers. These results align with expert clinical accounts that individuals with autism are often distressed by other individuals' negative emotions as well as with personal accounts from individu- als with ASD who describe eye contact as stressful (e.g., Trevisan, Roberts, Lin, & Birmingham, 2017).
4.2 | Heightened personal distress
Previous research has found that contagious itch is related to indi- vidual traits of neuroticism. Neuroticism is the tendency for indi- viduals to feel unpleasant emotions, and thus an important possible explanation for the current pattern of results is that contagious itch- ing may be related to one component of empathy: personal distress. Davis (2018) argues that the emotional component of empathy can be divided into a combination of empathic concern, the tendency to experience other-oriented feelings of sympathy and compassion in response to another's misfortune, and personal distress, the ten- dency to experience self-oriented feelings of discomfort and anxiety in response to another's misfortune. Presumably the newborn infant who cries in the nursery upon hearing another infant's cry, despite perceiving and mimicking the other's actions, thus bringing their own inner state closer to that of the target, is unable to distinguish self from other, much less feel empathetic concern for the other infant. Thus, it is conceivable that feeling personal distress at the arousal of others via emotional contagion is the earliest component of either emotional or cognitive empathy to develop.
There is some evidence that individuals with ASD self-re- port lower levels of empathic concern and higher or equal levels of personal distress compared to controls (Dziobek et al., 2008; Lombardo, Barnes, Wheelwright, & Baron-Cohen, 2007; Minio- Paluello et al., 2009). In addition, at-risk infants later diagnosed with ASD show higher levels of personal distress than their counterparts who do not go on to receive a diagnosis (Brian et al., 2008; Bryson et al., 2007). Finally, children with ASD show greater negative affect to negative emotional displays and less positive affect to positive emotional displays, both via parent report, and as measured in the laboratory (Capps, Kasari, Yirmiya, & Sigman, 1993).
In typical development, children are initially overwhelmed by the emotional experience of observing a person in need of help; as they mature, they learn to manage this emotional reaction, and in turn in- creasingly engage in pro-social helping behaviors (e.g., Batson et al., 1991). Thus, if personal distress levels remain high for individuals with ASD, this could have the consequence of stalling further em- pathic development. According to this account, one would expect individuals with ASD to show increased autonomic reactivity when witnessing others' distress, and when confronted with social stimuli that might be perceived as aversive and/or that are actively avoided (such as itching).
4.3 | Emotional valence
Another explanation for the increased rate of contagious itch among participants with ASD in this study may be that people on the au- tism spectrum react differently to stimuli with negative versus positive or neutral valence. It is possible that the aspect of the contagious itch stimuli that best explains the current results is not the fact that the signal was not transmitted from the eyes or face, or as a result of any increased aspect of emotional empathy, but rather that itching, un- like laughter and yawning, is negatively valenced. Contagious itching stimuli may induce feelings of discomfort in the observer and ignite a desire to "avoid" the source of this feeling and behavior (indeed, many definitions of itch use the word "unpleasant," and feelings of itch are related to feelings of state anxiety; Ogden & Zoukas, 2009). In contrast, contagious laughter and yawning may be more likely to engage "approach" and "affiliative" regions of the brain. For exam- ple, it is presumably adaptive for an organism to behaviorally syn- chronize with its social group if they are laughing or yawning so that the organism may share in the group's increased decompression or vigilance. In contrast, when viewing members of one's social group scratching, it is presumably adaptive to mobilize and "avoid" others and start scratching lest the organism catch the skin condition or insect bite that is causing their conspecifics' itching.
4.4 | Tactile defensiveness
A final possibility is that contagious itch is related to other traits as- sociated with ASD, such as sensory abnormalities, including tactile defensiveness, or possibly increased rates of atopic dermatitis, which itself entails itching that drives this relationship. Tactile de- fensiveness is characterized by behaviors, such as rubbing, scratch- ing, negative expressions, withdrawal, or avoidance in response to tactile stimulation and is linked to the rigid or inflexible behaviors, repetitive verbalizations, and visual stereotypies, that are often as- sociated with ASD (Baranek & Berkson, 1994). Children with these types of sensitivities might both be expected to show more itch at baseline (as was found) and to be more distressed by the sight of others itching. In addition, contagious itch is higher among pa- tients with atopic dermatitis (Papoiu et al., 2011), and there have been some studies suggesting that individuals with ASD have an increased risk of presenting with atopic dermatitis compared with typically developing controls, although results have been incon- sistent (Billeci et al., 2015). In the current study, we found that chil- dren with ASD itched more at baseline, which may reflect these sensory/dermatological differences. However, only contagious itching, and not baseline itching, was positively correlated with au- tism symptoms.
4.5 | Limitations and future directions
Interpretation of the current study is limited in several ways. First, the
present study did not employ eye tracking and so does not shed light on the role of visual attention to the eye region in behavioral conta- gion. Second, we did not assess individual components of empathy or tactile defensiveness in our ASD participants. Future studies may benefit from using a more fine-grained measure of empathy to directly investigate whether contagious itching is related to any particular components of empathy, such as personal distress. In addition, future research that examines contagion of both positively and negatively valenced stimuli from both the face and body may tease apart the pos- sible reasons why contagious itch is heightened in this population.
4.6 | Conclusion
Children with ASD appear to be capable of spontaneously internalizing the bodily signals of unfamiliar others and so as to come into bodily resonance those around them, and, in the case of contagious itch, dem- onstrate a heightened tendency to do so, while at the same time dis- playing a markedly reduced tendency to do so in the case of contagious yawning and laughter. People with ASD are often successfully able to do something under some circumstances (in this case, take on a bodily signal of contagion) that they fail to do automatically under other cir- cumstances. This type of observation should steer research away from theories that propose modular deficits in a particular structure of the brain or type of neuron, and toward accounts that invoke differences in behavioral profiles in attention and motivation, which are likely to determine the boundary conditions within which key social functions, like contagion, can be implemented. In addition, the implications of an intact but underused system imply that mass opportunities for these
early (often missed) experiences of shared affect, especially interac- tions involving attention to others' faces and eyes and imitation, may benefit the child's ability build a more efficient and automatic mirroring neural network. Early intervention holds the possibility of programming these early experiences, in addition to increasing the positive reward value of social interactions, by using various reinforcement and altering overwhelming contexts, and desensitizing tactile, eye gaze, and other sensory sensitivities. Improvement in spontaneous emotional conta- gion may even serve as an outcome measure of effective treatment.