|
- mise à jour
du
- 12 novembre
2026
- Front
Psychiatry
- 2026;17:1879203
|
- Reduced
contagious yawning in psychiatric
disorders:
- a
systematic review of potential social-cognitive
mechanisms
- Boiangiu R, Peleg R.
-
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|
- Tous
les articles sur la contagion du
bâillement
- All
articles about contagious
yawning
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- Contagious yawning has been proposed to
reflect multiple aspects of social cognition,
including empathy, emotional contagion,
self-processing, Theory of Mind (ToM), and
action observation mechanisms such as the human
mirror neuron system (hMNS). However, its
underlying mechanisms remain debated, with
evidence suggesting additional roles for social
attention, gaze allocation, social motivation,
and neurobiological factors. This systematic
review examined evidence for reduced contagious
yawning in Autism Spectrum Disorder (ASD),
schizophrenia-spectrum disorders, and
psychopathic traits, and evaluated potential
underlying mechanisms.
Methods: PubMed, PsycINFO, and Scopus
were systematically searched for clinical and
mechanistic studies of contagious yawning in
psychiatric and healthy populations. Studies
were screened using predefined eligibility
criteria, and risk of bias was assessed using
design-specific Joanna Briggs Institute (JBI)
critical appraisal tools. Twenty-three studies
met the inclusion criteria.
Results: Reduced contagious yawning
was reported in ASD, psychopathic traits, and
schizophrenia-spectrum disorders, although
findings varied across conditions. In ASD,
reduced contagious yawning was associated with
social attention, gaze allocation,
oxytocin-related processes, and broader
social-cognitive differences. In psychopathic
traits, evidence more consistently implicated
affective-interpersonal traits and reduced
emotional responsiveness. Evidence for
schizophrenia-spectrum disorders was more
limited, with proposed mechanisms including
impairments in social cognition, ToM, negative
symptoms, and possible medication effects.
Neuroimaging and electrophysiological findings
implicate brain systems involved in social
cognition, self-processing, and action
observation, although the specific role of the
hMNS remains uncertain.
Discussion: Reduced contagious yawning
may reflect altered social-cognitive processing
rather than empathy alone, with contributing
mechanisms differing across psychiatric
conditions. Interpretation is limited by small
sample sizes, methodological heterogeneity, and
variation in study design. Further well-powered
studies are needed to clarify its
neurobiological basis and clinical significance.
On a émis l'hypothèse que le
bâillement contagieux reflète
plusieurs aspects de la cognition sociale,
notamment l'empathie, la contagion
émotionnelle, l'auto-centrisme, la
théorie de l'esprit (ToM) et des
mécanismes d'observation de l'action tels
que le système des neurones miroirs
humains (hMNS). Cependant, ces mécanismes
sous-jacents font encore l'objet de
débats, certaines données
suggérant que l'attention sociale,
l'orientation du regard, la motivation sociale
et des facteurs neurobiologiques jouent
également un rôle. Cette revue
systématique a examiné les
données indiquant une diminution du
bâillement contagieux dans les troubles du
spectre autistique (TSA), les troubles du
spectre schizophrénique et les traits
psychopathiques, et a évalué les
mécanismes sous-jacents potentiels.
Méthodes : Une recherche
systématique a été
menée dans PubMed, PsycINFO et Scopus
afin d'identifier des études cliniques et
mécanistiques sur le bâillement
contagieux chez des populations psychiatriques
et saines. Les études ont
été sélectionnées
à l'aide de critères
d'éligibilité
prédéfinis, et le risque de biais
a été évalué
à l'aide des outils d'évaluation
critique du Joanna Briggs Institute (JBI)
spécifiques à chaque type de
conception. Vingt-trois études
répondaient aux critères
d'inclusion.
Résultats : Une diminution du
bâillement contagieux a été
rapportée dans les TSA, les traits
psychopathiques et les troubles du spectre
schizophrénique, bien que les
résultats aient varié selon les
pathologies. Dans les TSA, la diminution du
bâillement contagieux était
associée à l'attention sociale,
à la distribution du regard, aux
processus liés à l'ocytocine et
à des différences socio-cognitives
plus générales. En ce qui concerne
les traits psychopathiques, les données
ont plus systématiquement mis en
évidence des traits affectifs et
interpersonnels ainsi qu'une
réactivité émotionnelle
réduite. Les données relatives aux
troubles du spectre schizophrénique
étaient plus limitées ; les
mécanismes proposés comprenaient
des troubles de la cognition sociale, de la
théorie de l'esprit (ToM), des
symptômes négatifs et
d'éventuels effets des traitements
médicamenteux. Les résultats de
neuroimagerie et d'électrophysiologie
impliquent des systèmes
cérébraux impliqués dans la
cognition sociale, le l'auto-centrisme et
l'observation de l'action, bien que le
rôle spécifique du hMNS reste
incertain.
Discussion : La diminution du
bâillement contagieux pourrait
refléter une altération du
traitement socio-cognitif plutôt que
l'empathie seule, les mécanismes en cause
variant selon les troubles psychiatriques.
L'interprétation est limitée par
la petite taille des échantillons,
l'hétérogénéité
méthodologique et les variations dans la
conception des études. D'autres
études dotées d'une puissance
statistique suffisante sont nécessaires
pour clarifier ses fondements neurobiologiques
et sa signification clinique.
- 1 Introduction
- Spontaneous yawning is an evolutionarily
conserved physiological behavior observed across
many mammalian and vertebrate species. Although
its precise function remains debated, proposed
roles include regulation of arousal and
vigilance, non-verbal social communication, and,
more controversially, respiratory modulation and
brain thermoregulation (1). Yawning is regulated
by a complex neuroanatomical network involving
the hypothalamus, particularly the
paraventricular nucleus (PVN), which is
influenced by neurotransmitter systems including
oxytocinergic, dopaminergic, and nitric oxide
pathways. These signals are integrated with
brainstem mechanisms and modulated by limbic and
cortical structures to produce the coordinated
yawning response (1, 2).
-
- Contagious yawning refers to the elicitation
of yawning following perception or mental
representation of another individual's yawn, in
contrast to spontaneous yawning, which is
primarily associated with internal physiological
states. Contagious yawning can be triggered by
multiple social cues, including observing a
yawning face, hearing a yawn, reading about
yawning, or thinking about yawning (3).
Experimental studies have demonstrated that
dynamic visual presentations of yawning faces
elicit more contagious yawning responses than
control facial expressions, supporting the
specificity of yawning as a socially relevant
stimulus (4). Furthermore, the phenomenon does
not appear to depend on a single facial feature
or viewing angle, suggesting involvement of
broader social perception mechanisms rather than
isolated stimulus detection (4).
-
- Several mechanisms have been proposed to
explain individual differences in contagious
yawning susceptibility. Early theories
emphasized the relationship between contagious
yawning and empathy, emotional contagion, and
social bonding, proposing that these processes
may contribute to the ability to resonate with
another individual's internal state (5, 6).
-
- Other theories have proposed that contagious
yawning may involve broader forms of
social-cognitive processing, including
self-processing, mental state attribution, and
Theory of Mind (ToM). ToM reflects the ability
to attribute mental states to oneself and
others, including inferring others' desires,
thoughts, and beliefs in order to predict
behavior (7). From an evolutionary perspective,
self-awareness has been proposed as an important
component of complex social cognition, enabling
individuals to distinguish between self and
others and supporting more advanced
representations of social interactions (8).
Consistent with this framework, Platek et al.
(9) demonstrated associations between contagious
yawning, self-face recognition, and ToM
performance, suggesting a potential relationship
between contagious yawning and processes
involved in self-other distinction. However,
systematic reviews have concluded that the
association between contagious yawning and
empathy remains inconsistent, indicating that
multiple cognitive and neurobiological
mechanisms may contribute to this phenomenon
(10, 11).
-
- Although empathy has traditionally been
regarded as one of the principal mechanisms
underlying contagious yawning, contemporary
models of social cognition conceptualize empathy
as a multidimensional construct comprising both
affective and cognitive components. Cognitive
empathy overlaps substantially with processes
such as mental state attribution and Theory of
Mind (ToM), whereas affective empathy is more
closely related to emotional contagion and
emotional responsiveness. These constructs
should therefore not be viewed as mutually
exclusive explanations but rather as
complementary components of broader
social-cognitive functioning. Accordingly, the
present review evaluates contagious yawning
within a multidimensional framework encompassing
empathy, social attention, emotional contagion,
mental state attribution, and action
observation, rather than assuming a single
underlying mechanism.
-
- Neuroimaging and electrophysiological
studies have further investigated the mechanisms
underlying contagious yawning. Mirror neurons
were originally described as neurons activated
during both action execution and observation,
and this system has been proposed to contribute
to understanding others' actions and social
cognition (12, 13). Several neuroimaging and
electrophysiological studies have identified
activation of brain regions involved in social
cognition during contagious yawning, including
regions implicated in mentalization,
self-processing, and neural systems proposed to
overlap with the human mirror neuron system
(hMNS) (5, 14&endash;16). Alongside the hMNS,
the default mode network (DMN), a large-scale
brain network including regions such as the
ventromedial prefrontal cortex (17) and
posterior cingulate cortex, has been implicated
in internally directed cognition,
self-processing, and ToM (17, 18). Given that
contagious yawning has been associated with
processes involving mentalization and self-other
distinction, the DMN has been proposed as a
potential neural framework that may interact
with action observation networks in supporting
this complex social-cognitive behavior.
-
- However, the contribution of the hMNS to
contagious yawning and its relationship with
empathy remain debated, and contagious yawning
is likely influenced by multiple interacting
processes rather than a single neural
mechanism.
-
- In the present systematic review, we focused
on reduced contagious yawning in Autism Spectrum
Disorder (ASD), schizophrenia-spectrum
disorders, and psychopathy. These disorders were
selected because they represent distinct
patterns of social-cognitive differences and
impairments. ASD is characterized by differences
in social attention, communication, and gaze
allocation, psychopathy is primarily associated
with reduced affective empathy and emotional
responsiveness, whereas schizophrenia-spectrum
disorders involve impairments in ToM, social
cognition, and negative symptoms. Examining
these conditions together may provide insight
into whether reduced contagious yawning reflects
a shared alteration in social-cognitive
processing or disorder-specific mechanisms.
-
- Because relatively few studies have examined
contagious yawning in clinically diagnosed
psychiatric populations, the present review also
includes investigations of trait-level
characteristics, including psychopathic and
schizotypal traits. Although findings from
trait-based studies cannot be considered
equivalent to observations in clinical
populations, they provide complementary insight
into dimensional variation in social-cognitive
functioning and may help identify mechanisms
that extend across traditional diagnostic
boundaries.
-
- 3.3 Cognitive and neurobiological
mechanisms associated with contagious
yawning
- Nine studies investigated cognitive and
neurobiological variables associated with
contagious yawning susceptibility.
-
- Several behavioral studies examined
associations between contagious yawning and
social-affective characteristics (6, 22, 23).
Franzen reported associations between contagious
yawning responses and measures related to
emotional attachment, interpersonal
relationships, or prosocial characteristics. Two
studies (6, 24) reported higher rates of
contagious yawning among individuals with closer
social relationships, including friends and
family members, compared with unfamiliar
individuals.
-
- In contrast, other studies did not identify
significant associations between contagious
yawning and empathy-related measures.
Bartholomew and Cirulli (10) examined individual
differences in contagious yawning susceptibility
and reported that these differences were not
explained by empathy scores, emotional
attachment, sleepiness, or circadian factors.
Similarly, Massen and Gallup (11) reviewed the
available literature and concluded that current
quantitative evidence does not establish
contagious yawning as a specific measure of
empathy.
-
- Neuroimaging studies investigated neural
responses during exposure to yawning stimuli in
paradigms designed to examine contagious
yawning. Studies using fMRI reported activation
in regions involved in social cognition,
self-processing, and action observation,
including the inferior frontal gyrus, posterior
cingulate cortex, precuneus, and ventromedial
prefrontal cortex (5, 14, 16, 25). These
findings reflect neural responses observed
during exposure to yawning stimuli and should
not be interpreted as demonstrating that these
regions directly cause the behavioral expression
of contagious yawning.
-
- Cooper et al. (15) examined
electrophysiological responses during
observation of yawning stimuli and reported mu
suppression in sensorimotor regions.
-
- 3.4 Contagious yawning in autism spectrum
disorder
- Several studies compared contagious yawning
responses between individuals with ASD and
typically developing (TD) control participants
and reported reduced contagious yawning
frequencies in ASD cohorts (26&endash;28).
-
- Giganti and Ziello (26) reported that group
differences were specific to contagious yawning,
as spontaneous yawning frequencies did not
differ between ASD and TD groups.
-
- Helt et al. (29) examined the relationship
between contagious yawning and emotional empathy
and reported a positive association between
contagious yawning and emotional empathy scores
in the TD group; this association was not
observed in the ASD group.
-
- Other studies investigated the influence of
social attention and gaze allocation on
contagious yawning responses. Senju et al. (30)
reported that when participants with ASD were
instructed to focus their gaze on socially
relevant facial regions, differences in
contagious yawning between ASD and TD groups
were reduced. Similarly, Helt et al. (31)
reported that differences between groups varied
according to stimulus characteristics, including
the use of familiar versus unfamiliar yawning
stimuli.
-
- Other studies further suggest that
contagious yawning may not be directly related
to autistic traits themselves, but rather to
specific mechanisms involved in processing
social cues. Chan and Tseng (32) examined
autistic traits in a non-clinical student
population and found no association between
autistic trait scores and contagious yawning
susceptibility. The authors suggested that
individuals who are more susceptible to
contagious yawning may show increased
sensitivity to the perceptual processing of
yawning cues rather than reflecting sensitivity
to broader emotional information conveyed by
others. In addition to cognitive and attentional
mechanisms, biological factors may also
contribute to individual differences in
contagious yawning responses. Mariscal et al.
(33) examined oxytocin concentrations in
children with ASD and reported a positive
association between blood oxytocin levels and
contagious yawning behavior.
-
- 3.5 Contagious yawning and psychopathic
traits
- Three studies examined the relationship
between contagious yawning and psychopathic
traits (29, 34, 35). All three studies
investigated community or student samples using
psychopathic trait measures rather than
clinically diagnosed psychopathy.
-
- Across these studies, higher psychopathic
trait scores were associated with reduced
contagious yawning susceptibility. Rundle (35)
reported negative associations between
contagious yawning and affective-interpersonal
dimensions of psychopathy, including callousness
and reduced emotional responsiveness.
-
- Additionally, Rundle et al. examined
physiological responses and reported that
startle response amplitude was associated with
contagious yawning susceptibility (35).
-
- 3.6 Contagious yawning in
schizophrenia-spectrum conditions
- Two studies provided data relevant to
schizophrenia-spectrum conditions.
-
- Haker and Rössler (36) examined
individuals with clinically diagnosed
schizophrenia and reported reduced contagious
yawning and contagious laughing responses
compared with healthy control participants.
-
- Platek et al. (9) investigated schizotypal
traits in a non-clinical sample of college
students. The authors reported a negative
association between schizotypal trait scores and
contagious yawning susceptibility. Additionally,
performance on ToM and self-face recognition
tasks was positively associated with contagious
yawning susceptibility.
-
- Because Platek et al. (9) examined
schizotypal traits rather than schizophrenia,
these findings provide information regarding
schizophrenia-spectrum characteristics but
cannot be directly generalized to individuals
with clinical schizophrenia.
-
- Accordingly, evidence from schizotypal
traits was considered complementary to, rather
than equivalent to, evidence from clinically
diagnosed schizophrenia.
-
- 4 Discussion
- This systematic review synthesized the
available evidence on contagious yawning across
Autism Spectrum Disorder (ASD), psychopathic
traits, and schizophrenia-spectrum disorders to
evaluate the social-cognitive mechanisms that
may underlie reduced contagious yawning. The
evidence base included both studies directly
examining psychiatric or clinically relevant
trait populations and mechanistic studies
conducted in non-clinical samples, which were
considered as complementary evidence regarding
potential underlying processes rather than as
evidence of psychiatric-group differences.
Across the reviewed literature, reduced
contagious yawning emerged as a relatively
consistent behavioral finding. However, the
evidence does not support a single explanatory
mechanism. Rather, the collective findings
indicate that contagious yawning is best
understood as a multidimensional
social-cognitive phenomenon involving the
interaction of social attention, emotional
responsiveness, interpersonal familiarity,
mental state attribution, and action
observation. Importantly, the evidence
supporting these mechanisms is not equally
robust. Behavioral studies consistently
implicate broader social-cognitive functioning,
whereas evidence for specific neurobiological
mechanisms remains comparatively limited.
Consequently, contagious yawning should be
interpreted as a potential behavioral marker of
social-cognitive functioning rather than as a
direct measure of empathy or any single
cognitive process.
-
- Another important observation is that
inconsistencies across studies are more likely
to reflect methodological heterogeneity than
genuine theoretical disagreement. Included
studies differed substantially in participant
characteristics, diagnostic definitions,
experimental paradigms, stimulus modality,
familiarity of yawning stimuli, eye-fixation
instructions, and outcome measures used to
quantify contagious yawning. Because these
paradigms engage partially distinct aspects of
social cognition, methodological variation
probably contributes to the variability of
reported findings. Therefore, apparently
conflicting results should be interpreted within
the methodological context of each study rather
than as evidence against particular theoretical
models.
-
- 4.1 Disorder-specific mechanisms
underlying reduced contagious yawning
- The findings of this review suggest that
although reduced contagious yawning has been
observed across ASD, psychopathic traits, and
schizophrenia-spectrum conditions, the
mechanisms contributing to this phenomenon may
differ substantially between disorders. These
conditions are characterized by distinct
patterns of social cognition, emotional
processing, and interpersonal functioning, and
therefore a single explanatory mechanism is
unlikely to account for reduced contagious
yawning across all populations.
-
- 4.1.1 Autism spectrum disorder
- Among the psychiatric conditions reviewed,
ASD provides the strongest evidence linking
reduced contagious yawning to alterations in
social-cognitive functioning. Multiple
independent studies consistently demonstrated
reduced contagious yawning in autistic
individuals compared with typically developing
controls (26&endash;28).
-
- Importantly, however, the collective
evidence indicates that reduced contagious
yawning in ASD is unlikely to be explained by
impaired empathy alone. Instead, the findings
consistently support a multifactorial model in
which social attention, gaze allocation,
emotional responsiveness, and contextual factors
interact to influence susceptibility to
contagious yawning.
-
- One of the most compelling findings concerns
the role of visual attention. Senju et al. (30)
demonstrated that directing children with ASD to
fixate on the eye region substantially reduced
the difference in contagious yawning between
autistic and typically developing participants.
Together with evidence of atypical gaze patterns
in ASD (38), these findings suggest that
diminished contagious yawning may result, at
least in part, from reduced attention to
socially relevant cues rather than an intrinsic
inability to respond empathically. Similarly,
Helt et al. (31) showed that contagious yawning
varied according to stimulus familiarity and
task instructions, further indicating that
contextual and attentional factors significantly
influence yawning susceptibility. Collectively,
these experimental manipulations provide
stronger support for attentional mechanisms than
would be obtained from observational
associations alone.
-
- The distinction between contagious and
spontaneous yawning provides additional support
for this interpretation. Giganti and Ziello (26)
reported that although children with ASD
exhibited significantly reduced contagious
yawning, spontaneous yawning frequency did not
differ from that of typically developing
controls. This finding argues against a general
physiological impairment in yawning and instead
suggests that the observed deficit is specific
to socially elicited yawning, reinforcing the
involvement of higher-order social-cognitive
processes.
-
- Nevertheless, the ASD literature also
illustrates why contagious yawning should not be
interpreted as a simple behavioral proxy for
empathy. Mariscal et al. (33) found no overall
difference in contagious yawning between
autistic and typically developing children while
reporting a positive association between
oxytocin concentration and contagious yawning
within the ASD group. Although these findings
raise the possibility that neurobiological
factors contribute to contagious yawning
susceptibility, they are based on a single study
and therefore provide only preliminary evidence.
Similarly, while several studies have linked
contagious yawning to emotional contagion or
empathic processes, the collective literature
suggests that these mechanisms operate alongside
attentional and social-cognitive factors rather
than independently explaining contagious
yawning.
-
- Overall, the evidence for ASD is both the
most extensive and the most methodologically
convincing among the psychiatric conditions
reviewed. Multiple studies have replicated
reduced contagious yawning using different
experimental paradigms, and several have
experimentally manipulated variables such as
gaze direction and stimulus familiarity,
strengthening confidence in the observed
behavioral associations. At the same time,
methodological differences in participant age,
autism severity, and experimental design likely
contribute to residual inconsistencies across
studies. Consequently, current evidence supports
reduced contagious yawning in ASD as a robust
behavioral finding while favoring a
multidimensional social-cognitive interpretation
over explanations based solely on empathy
deficits.
-
- 4.1.2 Psychopathic traits
- Compared with ASD, the evidence linking
psychopathic traits to reduced contagious
yawning is less extensive but relatively
consistent. Across the reviewed studies,
individuals with higher levels of psychopathic
traits generally exhibited reduced
susceptibility to contagious yawning (29, 34,
35), suggesting that this association is
reproducible despite the smaller evidence base.
However, because nearly all studies were
conducted in non-clinical populations,
confidence in the generalizability of these
findings to individuals with clinically
diagnosed psychopathy remains moderate.
-
- Unlike the ASD literature, the findings in
psychopathy provide less support for attentional
explanations and instead point toward
alterations in affective and interpersonal
functioning. Rundle et al. (35) reported that
psychopathic characteristics associated with
reduced emotional responsiveness predicted lower
contagious yawning susceptibility, while Gallup
et al. (34), using one of the largest samples
included in this review, similarly demonstrated
an inverse relationship between psychopathic
traits and contagious yawning. Helt et al. (29)
further showed that individuals with elevated
psychopathic traits displayed patterns of
contagious yawning that differed from those
associated with autistic traits, suggesting that
superficially similar behavioral outcomes may
arise through different underlying
mechanisms.
-
- Importantly, these findings argue against
interpreting contagious yawning as a direct
measure of empathy. Although psychopathy is
characterized by impairments in affective
empathy, aspects of cognitive social
functioning, including mental state attribution,
may remain relatively preserved (39). If
contagious yawning reflected empathy alone,
stronger and more consistent associations would
be expected across psychopathy studies. Instead,
the reviewed evidence suggests that contagious
yawning is influenced by a broader constellation
of social-cognitive processes, including
emotional salience, interpersonal engagement,
and social motivation. This interpretation is
consistent with the broader conclusions of the
present review, which indicate that empathy
contributes to&emdash;but does not fully
explain&emdash;contagious yawning.
-
- Although the psychopathy studies were
generally adequately reported, the evidence
remains limited by the characteristics of the
available samples. Most investigations examined
psychopathic traits in community or university
populations rather than clinically diagnosed
psychopathy, limiting direct clinical
interpretation. Consequently, while reduced
contagious yawning appears to represent a
reliable behavioral correlate of psychopathic
traits, further research involving
well-characterized clinical samples is required
before disorder-specific conclusions can be
drawn.
-
- 4.1.3 Schizophrenia-spectrum
disorders
- Evidence regarding schizophrenia-spectrum
disorders remains the most limited among the
psychiatric conditions reviewed. This should not
be interpreted as evidence against an
association between schizophrenia-spectrum
pathology and contagious yawning, but rather as
reflecting the scarcity of available research.
Only two studies met the inclusion criteria, one
involving individuals with clinically diagnosed
schizophrenia (36) and the other examining
schizotypal personality traits in a non-clinical
sample (9). Although both studies reported
reduced contagious yawning, the small evidence
base substantially limits confidence in
mechanistic interpretations.
-
- Haker and Rössler (36) found that
individuals with schizophrenia exhibited reduced
contagious yawning and contagious laughter
compared with healthy controls. Notably, these
reductions were not significantly associated
with empathy measures, suggesting that
diminished contagious yawning cannot be
explained solely by impaired empathic
functioning. Similarly, Platek et al. (9)
reported that higher schizotypal traits were
associated with reduced contagious yawning while
also demonstrating relationships with Theory of
Mind and facial recognition performance. Because
schizotypal traits represent a recognized
vulnerability phenotype for schizophrenia (41),
these findings provide indirect support for the
broader relevance of social-cognitive
dysfunction within the schizophrenia spectrum.
Nevertheless, results obtained in non-clinical
populations should not be considered equivalent
to findings in patients with schizophrenia.
-
- Overall, the available evidence suggests
that reduced contagious yawning in
schizophrenia-spectrum disorders is more likely
to reflect generalized disturbances in social
cognition than deficits in any single
psychological process. Schizophrenia is
characterized by impairments in multiple
domains, including Theory of Mind, emotion
recognition, social perception, and
interpersonal functioning (40), each of which
could plausibly influence contagious yawning
susceptibility. At present, however, the
relative contribution of these mechanisms cannot
be determined because of the limited number of
available studies.
-
- Interpretation of the schizophrenia
literature is further complicated by
methodological factors. Clinical samples
differed with respect to illness duration,
symptom severity, medication status, and
cognitive functioning, variables that were not
consistently controlled across studies. In
addition, schizophrenia is frequently associated
with abnormalities in eye movements and visual
exploration (42), potentially influencing
attention toward socially relevant cues
independently of social-cognitive impairment.
Together, these factors introduce potential
sources of heterogeneity that further reduce
certainty regarding the underlying mechanisms.
Consequently, although current findings
consistently point toward reduced contagious
yawning, confidence in disorder-specific
conclusions remains lower than for ASD and
psychopathic traits.
-
- 4.2 Neurobiological mechanisms and the
human mirror neuron system
- The neurobiological evidence reviewed in
this study supports the involvement of
distributed neural systems rather than a single
mechanism underlying contagious yawning. Across
neuroimaging and electrophysiological studies,
exposure to yawning stimuli was associated with
activation or modulation of brain regions
implicated in action observation,
self-referential processing, mental state
attribution, and broader social cognition,
including the inferior frontal gyrus, posterior
cingulate cortex, precuneus, and ventromedial
prefrontal cortex (5, 14, 16, 25). Collectively,
these findings are consistent with the
behavioral evidence presented throughout this
review, suggesting that contagious yawning
reflects the coordinated interaction of multiple
social-cognitive processes.
-
- The human mirror neuron system (hMNS) has
received particular attention because of its
established role in action observation and
imitation (12, 13). Functional neuroimaging
demonstrating inferior frontal gyrus activation
(5) and electrophysiological evidence of mu
suppression during yawning observation (15)
provide preliminary and indirect evidence
consistent with the possible involvement of
neural systems associated with action
observation, including the human mirror neuron
system (hMNS). However, the current evidence
does not justify interpreting the hMNS as the
primary mechanism underlying contagious yawning
or its reduction across psychiatric
disorders.
-
- Several factors warrant caution. First, the
available neurobiological studies are relatively
few and generally involve small samples,
limiting statistical power and reducing
confidence in the reproducibility of individual
findings. Second, the neural regions implicated
in contagious yawning are not specific to this
behavior but are also involved in multiple
domains of social cognition, including empathy,
mentalizing, self-other distinction, and action
understanding.
-
- Finally, the available neurobiological
studies were generally limited by small samples
and by the use of experimental paradigms that
primarily assessed neural responses during
exposure to yawning stimuli. These findings
therefore provide evidence of neural involvement
but do not establish that the observed neural
activity causes contagious yawning behavior.
Consequently, current neurobiological evidence
should be viewed as complementary to the
behavioral literature rather than as definitive
support for any single mechanistic account.
-
-
- 4.5 Conclusions
- This systematic review synthesized the
available evidence regarding contagious yawning
across Autism Spectrum Disorder, psychopathic
traits, and schizophrenia-spectrum disorders
while critically evaluating the mechanisms
proposed to explain reduced contagious yawning.
Across these psychiatric conditions, reduced
contagious yawning emerged as a relatively
consistent behavioral finding. However, the
present review indicates that this phenomenon
cannot be adequately explained by a single
theoretical framework.
-
- Overall, the available evidence most
strongly supports interpreting contagious
yawning as a multidimensional marker of
social-cognitive functioning rather than as a
direct behavioral measure of empathy. Although
empathy may contribute to contagious yawning,
the findings reviewed here suggest that social
attention, interpersonal processing, emotional
responsiveness, mental state attribution, and
action observation all contribute to yawning
susceptibility, with their relative importance
varying across psychiatric conditions. Rather
than representing competing explanations, these
mechanisms are more appropriately viewed as
complementary processes operating within broader
social-cognitive networks.
-
- Importantly, the strength of evidence is not
equivalent across the proposed mechanisms.
-
- Behavioral evidence examining social
attention and interpersonal processing is
supported by multiple independent studies
employing diverse experimental paradigms. By
contrast, evidence supporting specific
neurobiological mechanisms remains preliminary
because it is derived primarily from a limited
number of mechanistic studies with relatively
small samples.
-
- Although the methodological appraisal
identified methodological strengths across the
reviewed studies, considerable heterogeneity in
study design, participant characteristics, and
contagious yawning paradigms limits direct
comparison across investigations and reduces
certainty regarding disorder-specific
mechanisms.
-
- Future research should therefore prioritize
standardized experimental paradigms, adequately
powered clinical samples, longitudinal designs,
and multimodal behavioral and neurobiological
approaches.
-
- A clearer understanding of these mechanisms
may ultimately determine whether contagious
yawning represents merely an experimental
phenomenon or a clinically informative
behavioral marker of social-cognitive
functioning across psychiatric disorders.
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