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- mise à jour
du
- 17 août
2024
- American
Journal of Primatology
- https://doi.org/10.1002/ajp.23671
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- Beware!
Different methods lead to divergent
results
- on yawn
contagion modulation in bonobos
- Sara De Vittoris, Marta Caselli, Elisa
Demuru,
- Lisa Gillespie, Ivan Norscia
-
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- Tous
les articles sur la contagion du
bâillement
- All
articles about contagious
yawning
-
- Abstract
- Contagious yawning (CY)&emdash;linked to
physiological synchronization and possibly
emotional contagion&emdash;occurs when one
individual's yawn induces yawning in others. CY
was investigated over different time windows
(minutes from the triggering stimulus) via
naturalistic or experimental studies (using real
and video yawns, respectively) with contrasting
results, especially in bonobos. The authors
verified whether in bonobos result divergences
may derive from different methods. They gathered
yawning data on 13 bonobos at Twycross Zoo (UK)
via a naturalistic (all-occurrences
observations) and experimental approach (by
showing yawn/control video stimuli). Based on
literature, we used 1- and 3-min windows to
detect CY. Due to fission-fusion management,
individuals could form permanent or
non-permanent associations (more/less familiar
subjects under naturalistic setting).
-
- Video yawn stimuli may come from group
mates/stranger models (more/less familiar
subjects under the experimental setting).
Stimulus type and time window affected CY
modulating factors but not CY detection.
Familiarity and age effect on CY showed opposite
trends in 3-min trials and 1-min observations.
CY was highest in oldest, non-permanently
(rather than permanently) associated subjects in
the naturalistic setting, but in the youngest
subjects and with ingroup (rather than outgroup)
models in trials. The age effect differences on
CY might be due to decontextualized yawns and
immature subject curiosity toward videos. The
reversed familiarity effect suggests CY's
context-dependent function in promoting social
synchronization with socially distant group
mates, as failing to coordinate as a group may
lead to social disruption. Complementary methods
are needed to fully understand motor replication
phenomena.
-
- Résuumé
- La répilcation du bâillement
(CY) - lié à la synchronisation
physiologique et peut-être à la
contagion émotionnelle - se produit
lorsque le bâillement d'un individu induit
le bâillement des autres. Le CY a
été étudié sur
différentes fenêtres temporelles
(en minutes à partir du stimulus
déclencheur) par le biais d'études
naturalistes ou expérimentales (utilisant
des bâillements réels et
vidéo, respectivement) avec des
résultats contrastés, en
particulier chez les bonobos. Les auteurs ont
vérifié si, chez les bonobos, les
divergences de résultats pouvaient
provenir de méthodes différentes.
Ils ont recueilli des données sur les
bâillements de 13 bonobos du zoo de
Twycross (Royaume-Uni) par le biais d'une
approche naturaliste (observations de toutes les
occurrences) et expérimentale (en
montrant des stimuli vidéo de
bâillement/contrôle). Sur la base de
la littérature, Ils ont utilisé
des périodes de 1 et 3 minutes pour
détecter les CY. En raison de la gestion
de la fission-fusion, les individus peuvent
former des associations permanentes ou non
permanentes (sujets plus ou moins familiers dans
un contexte naturaliste).
-
- Les stimuli vidéo de bâillement
peuvent provenir de congénères du
groupe ou d'étrangers (sujets plus ou
moins familiers dans le cadre de
l'expérience). Le type de stimulus et la
fenêtre temporelle ont affecté les
facteurs de modulation du CY mais pas la
détection du CY. L'effet de la
familiarité et de l'âge sur le CY a
montré des tendances opposées dans
les essais de 3 minutes et les observations de 1
minute. Le CY était le plus
élevé chez les sujets les plus
âgés, non associés de
manière permanente (plutôt que
permanente) dans le contexte naturaliste, mais
chez les sujets les plus jeunes et avec les
modèles de l'ingroupe (plutôt que
de l'outgroupe) dans les essais. Les
différences d'effet d'âge sur le CY
pourraient être dues à des
bâillements décontextualisés
et à la curiosité immature des
sujets à l'égard des
vidéos. L'effet de familiarité
inversé suggère la fonction
contextuelle de CY dans la promotion de la
synchronisation sociale avec des camarades de
groupe socialement éloignés, car
l'absence de coordination en tant que groupe
peut entraîner une perturbation sociale.
Des méthodes complémentaires sont
nécessaires pour comprendre pleinement
les phénomènes de
réplication motrice.
- INTRODUCTION
- Contrary to spontaneous yawning, contagious
yawning occurs when the yawn of an individual
(responder) is induced by the perceived yawn of
another individual (trigger; [Provine,
1989]). In this respect the yawn of an
individual acts as releasing stimulus (sensu
Tinbergen, 1952). Yawn contagion has been
investigated in various primate species spanning
strepshirrhines and haplorrhines using
naturalistic observations (with real yawn
stimuli) for some species (e.g., Gallo et al.,
2021; Palagi et al., 2009; Valdivieso-Cortadella
et al., 2023; Valente et al., 2023) and an
experimental trials with video stimuli for
others (e.g., Palagi & Norscia, 2019;
Paukner & Anderson, 2006; Pedruzzi et al.,
2022; Reddy et al., 2016; van Berlo et al.,
2020). Few species have been studied with both
methods, and even fewer with both approaches in
the same study (e.g., Norscia et al., 2021a;
Palagi et al., 2019). The use of different types
of stimuli (video vs. real yawns) has led (with
one exception only) to generally consistent
results with respect to the presence of yawn
contagion in the few species where different
types of stimuli were used (although rarely in
the same study). Yawn contagion was not detected
in gorillas (Gorilla gorilla gorilla) across
methods (video stimuli: Amici et al., 2014;
naturalistic observations: Palagi et al., 2019),
yet was consistently observed in chimpanzees
(Pan troglodytes) both experimentally (Anderson
et al., 2004; Campbell & de Waal, 2011;
Campbell et al., 2009) and under naturalistic
conditions (Campbell & Cox, 2019). In
bonobos (Pan paniscus), it was reported in two
studies under naturalistic conditions (Demuru
& Palagi, 2012; Norscia et al., 2022) and
one experimental study (Tan et al., 2017), but
not in another study (Amici et al., 2014). In
humans (Homo sapiens), naturalistic observations
(Norscia & Palagi, 2011; Norscia et al.,
2021a) or video stimuli (Bartholomew &
Cirulli, 2014; Chan & Tseng, 2017; Provine,
1986, 1989) have confirmed the presence of yawn
contagion, originally described by Provine
(1986, 1989) by using experiential trials.
-
- As an automatic response that is not purely
motoric but is also based on autonomic
processes, yawn contagion may occur from
immediately to several minutes after perceiving
a yawn (Palagi et al., 2020; Prochazkova &
Kret, 2017). Different time windows have been
used to detect yawn contagion, spanning 20_s to
several minutes after the triggering stimulus
(Kapitány & Nielsen, 2017). The
choice of the time window duration is a
sensitive matter because it bears the risk of
including either false positives (if the time
window is too long)&emdash;that is yawns
considered as induced by contagion when they are
spontaneous&emdash;or false negatives (if the
time window is too short)&emdash;that is yawns
considered as spontaneous when they are elicited
by contagion (Kapitány & Nielsen,
2017; Norscia & Palagi, 2011). Some studies
used 5_min as a time latency (Palagi et al.,
2009), but since autocorrelation (the fact that
a yawn performed by a subject at t0 may increase
the likelihood of inducing another yawn by the
same subject at t0+X) can be highest at the
fourth minute (Kapitány & Nielsen,
2017), most studies have settled on a time
window of 3 min (naturalistic conditions; lions,
Panthera leo: Casetta et al., 2021; pigs, Sus
scrofa: Norscia et al., 2021b; indri, Indri
indri: Valente et al., 2023; spider monkeys,
Ateles geoffroyi: Valdivieso-Cortadella et al.,
2023; geladas, Theropithecus gelada: Gallo et
al., 2021; bonobos: Demuru & Palagi, 2012;
Norscia et al., 2022; humans: Norscia &
Palagi, 2011; bonobos/humans: Palagi et al.,
2014; video stimuli; red-capped mangabeys,
Cercocebus torquatus: Pedruzzi et al., 2022;
stumptail macaques, Macaca arctoides: Paukner
& Anderson, 2006; chimpanzees: Anderson et
al., 2004). Hence, the 3-min time range may
reduce the probability of autocorrelation
(Kapitány & Nielsen, 2017) and the
likelihood of considering a spontaneous yawn as
one resulting from contagion. Indeed, in
hominins yawn contagion has been mostly detected
in the 3-min time window, with a pick in the
first minute (chimpanzees: Campbell & de
Waal, 2011; humans: Norscia & Palagi, 2011;
bonobos/humans: Palagi et al., 2014) and in one
case for chimpanzees within 3.5_min with a pick
at 1.5_min (over a longer time slot; Campbell
& Cox, 2019). The situation in bonobos is
particularly tricky, because one study reported
a pick of yawn contagion in the first minute
(Demuru & Palagi, 2012) and another that
yawn contagion only occurred within 1 min
(Norscia et al., 2022). In light of the above,
and because this study is focused on bonobos, we
used both the 3- and 1-min time windows to
understand whether the use of different time
windows can lead to divergent results regarding
yawn contagion.
-
- Besides the presence/absence of yawn
contagion, the use of different approaches may
affect the amount of detected contagion, which
in turn can lead to differences in the detection
of modulating factors. In humans, an effect of
familiarity has been verified only via
naturalistic observations (with yawn contagion
increasing as familiarity increases; Norscia
& Palagi, 2011; Norscia et al., 2020;
Norscia et al., 2021a). However, the general
yawning response in humans (along with other
motor mimicry responses) to prerecorded video
stimuli can be weaker than the response observed
in real, face-to-face interactions (Diana et
al., 2023). Because the modulating factors
precisely act on the amount of yawn contagion
(by increasing or decreasing it), possible
differences may emerge when comparing the
results obtained from video and real stimuli in
humans. In bonobos, the results coming from
video and naturalistic studies reported either
no differences or stronger contagion between
more familiar subjects (Demuru & Palagi,
2012; Norscia et al., 2022; Tan et al., 2017).
To our knowledge no other species have been
studied with respect to modulating factors
(e.g., familiarity, age, sex) by using both
naturalistic observations and
video-stimuli.
-
- A critical point is that what we know about
yawn contagion in different species is based on
single or very few case studies, and on the use
of either method (naturalistic observations or
experimental trials), with rare exceptions
(Palagi et al., 2020). This study is not as much
focused on the phenomenon of yawn contagion per
se. Rather, it is focused on whether the
diverging results can actually be ascribed to
different methodological approaches and on how
to interpret the possible result differences. To
this purpose, we carried out both experimental
trials (by showing yawn/control video stimuli)
and observational data collection (involving the
display of real yawns) on the same individuals
of a bonobo colony housed at Twycross Zoo (UK).
Bonobos are a good model to investigate this
aspect because there are enough studies on yawn
contagion that suggest that some apparently
contrasting results may derive from the use of
different methodological approaches (Amici et
al., 2014; Demuru & Palagi, 2012; Norscia et
al., 2022; Palagi et al., 2014; Tan et al.,
2017). Such studies are enough to allow general
predictions, which are listed here below.
-
- Presence of yawn contagion. Because in
bonobos yawn contagion has been found in both
experimental and naturalistic studies using
different time windows (Demuru & Palagi,
2012; Norscia et al., 2022; Tan et al., 2017),
we expected that the phenomenon could be
detected with both naturalistic and experimental
settings (Prediction 1a), and different time
windows (Prediction 1b).
-
- Modulation of yawn contagion. Video and
naturalistic studies apparently report
contrasting results on the effect of familiarity
on yawn contagion in bonobos (Demuru &
Palagi, 2012; Norscia et al., 2022; Tan et al.,
2017). However, familiarity determination had a
different basis in video and naturalistic
studies. In experimental video studies,
familiarity level was based on whether the video
shows group-mate or stranger models (Tan et al.,
2017). In the naturalistic approach, familiarity
level was based on the level of association
(e.g., affiliation) between group members (no
strangers were present in the group, only more
or less familiar subjects; Demuru & Palagi,
2012; Norscia et al., 2022). No information is
available on possible differences in the effect
of age or sex because only naturalistic studies
considered these variables (Demuru & Palagi,
2012; Norscia et al., 2022). However, yawn
contagion can be affected by the method in
humans (prerecorded video stimuli/real yawns;
Diana et al., 2023) and by the time elapsed from
the yawning stimulus in great apes and humans
(Campbell & Cox, 2019; Demuru & Palagi,
2012; Norscia & Palagi, 2011; Norscia et
al., 2022). Because modulation acts on the
amount of yawn contagion, we expected that the
yawn contagion rates within different time
window would not necessarily correlate between
methods (Prediction 2a), and to find differences
in the factors that can influence yawn contagion
when considering different methods (Prediction
2b) and time windows (Prediction 2c). However,
it was not possible to predict any specific
direction.
-
- DISCUSSION
- Our study shows that the use of different
methodological approaches&emdash;involving real
vs. video stimuli and checking for yawning
responses over different time windows (1 or
3_min from the triggering stimulus)&emdash; can
indeed lead to diverging results. We considered
the same subjects, in the same location and with
the same data collector/experimenter for both
the naturalistic setting where yawning responses
to others' yawns were recorded and the
experimental trials where bonobos watched
yawn/control video stimuli. Here we discuss
whether the detected differences can be
considered as actually contradictory
or&emdash;rather&emdash;can be complemented into
a comprehensive picture on the phenomenon of
yawn contagion in bonobos.
-
- 4.1 Presence of yawn contagion
- Our study confirms that yawn contagion in
bonobos can be detected via both naturalistic
behavioral collection and experimental trial
methods (Prediction 1a confirmed; Figures 2 and
3), as it was expected considering that most of
the previous literature described the phenomenon
in bonobos by using either method (naturalistic
conditions: Demuru & Palagi, 2012; Norscia
et al., 2022; video stimuli: Tan et al., 2017;
but see Amici et al., 2014). Similarly, in the
two other extant hominin species (humans and
chimpanzees) yawn contagion was consistently
found by using either an experimental approach
(e.g., Bartholomew & Cirulli, 2014; Campbell
& de Waal, 2011; Provine, 1986, 1989) or
naturalistic observations (e.g., Norscia &
Palagi, 2011; Norscia et al., 2016) and in
humans when using both methods (Norscia et al.,
2021a).
-
- In both naturalistic and experimental
settings, we detected yawn contagion within both
1 and 3_min from the triggering stimulus
(Prediction 1b confirmed; Figures 2 and 3). This
result is in line with the fact that in bonobos
the phenomenon has been found by using different
time windows, e.g., 10_min video stimuli (Tan et
al., 2017 via video trials) or 3_min (Demuru
& Palagi, 2012 under naturalistic
conditions). In other hominins, namely
chimpanzees and humans, yawn contagion has been
found within 3.5 and 3_min respectively, with
pick observed around 1.5 and 1_min, respectively
(Campbell & Cox, 2019; Campbell & de
Waal, 2011; Norscia & Palagi, 2011; Palagi
et al., 2014). Hence, it is possible that in
hominins the time windows within 3_min do not
much affect the likelihood of detecting
contagion. Because this time window may decrease
the autocorrelation likelihood (Kapitány
& Nielsen, 2017), the variability in yawn
contagion detection probability may also be
reduced. However, in a study of bonobos, Norscia
et al. (2022) observed yawn contagion only in
the first out of 3 min and Amici et al. (2014)
detected no yawn contagion in four bonobos over
a 3-min span. This variability, as noted by
Norscia et al. (2022), may arise from
significant interindividual differences, with
not all individuals showing contagion. Thus,
individual characteristics and group composition
could affect the detection of this phenomenon,
suggesting that this aspect deserves further
research.
-
- 4.2 Factors modulating yawn
contagion
- While the presence of yawn contagion in
bonobos could be consistently detected between
naturalistic and experimental setting,
regardless of the time-window, we found no
correlation in the individual yawn contagion
rates (measured via YCIs; Prediction 2a
confirmed). Consistently, the factors that can
modulate yawn contagion levels differed across
the methods and time windows considered.
Although sex had no effect&emdash; possibly due
to variability across bonobo groups and
individuals, which makes it hard to find
consistent results (Demuru & Palagi, 2012;
Norscia et al., 2022) other modulating factors
were influenced by method and time window
(Prediction 2b-c confirmed). We found that in
naturalistic conditions, an effect of
familiarity (individual staying always or not
always together) and age were detected only in
the 1-min time window (Figure 4). This result
may be due to the fact that&emdash;precisely
under naturalistic conditions&emdash;yawn
contagion in bonobos has been found to peak or
be only present in the first minute (Demuru
& Palagi, 2012; Norscia et al., 2022).
Similarly, under naturalistic conditions a peak
of yawn contagion was observed after 1.5_min
after the triggering stimulus in chimpanzees
(Campbell & Cox, 2019) and in the first
minute in humans (Norscia & Palagi, 2011).
Because yawn contagion rates plummet after the
first minute, it is possible that in later
minutes low contagion levels leave little margin
for modulating factors to effectively act in
increasing or decreasing the amount of yawn
contagion. Although in a different way, this
issue also affected video trials. We found that
in experimental trials, the factors that
influence yawn contagion emerged only using the
3-min time (Figure 5). In humans, Diana et al.
(2023) observed that video stimuli induced yawn
contagion at lower rates than real stimuli. More
minutes may be necessary under video conditions
to record yawn contagion at sufficiently high
rates that allow the modulating factors to
intervene. This aspect may be related to the
fact video stimuli - even if repeatedly shown to
the experimental subjects - are possibly more
effective in inducing yawn contagion over a
longer period of time, which results in the
increased latency in the yawning response onset.
In bonobos, yawn contagion elicitation may
require longer time with non-real, video stimuli
(e.g., 10_min: Tan et al., 2017 vs. 3_min: Amici
et al., 2014) but also this aspect requires
further investigation.
-
- The crucial point of this study is
that&emdash;when detected&emdash;the yawn
contagion factors modulating were similar (age
and familiarity) but had apparently opposite
effects on the phenomenon. Yawn contagion was
highest in older bonobos and between less
familiar individuals in the naturalistic setting
(1-min time window) whereas it was highest in
younger bonobos and in response to in-group
members (rather than strangers) in the
experimental setting (3-min time window).
-
- As concerns age, the increase of yawn
contagion with age observed in naturalistic
conditions is not in contrast with literature.
Indeed, yawn contagion tends to be absent or be
present at low rates in immature humans
(Anderson & Meno, 2003; Cordoni et al.,
2021; Helt et al., 2010; Millen & Anderson,
2011) and has not been detected so far in infant
bonobos and chimpanzees (Madsen et al., 2013;
Norscia et al., 2022). In human and nonhuman
mammals, the increase of yawn contagion with age
can be possibly linked with the maturation of
neurobiological substrates underlying the
ability to decode social cues and identify the
internal states of others (Cordoni et al., 2021;
Norscia et al., 2021b). On the other hand, also
the decrease of yawn contagion with age observed
in the experimental setting is not inconsistent
with previous studies, as yawn contagion has
been observed to decrease with aging in certain
cohorts of humans (people over 40; Bartholomew
& Cirulli, 2014) and bonobos (Norscia et
al., 2022). This trend might be linked to
decreased sensitivity to others' states and in
humans to increased replacement of bottom-up
with top-down processes in emotional appraisal
(Norscia et al., 2022; Petro et al., 2021; Reed
& Carstensen, 2012). Either way (increasing
or decreasing yawn contagion rates as age
increases), the main point here is that two
different methods led to divergent results with
respect to the same modulating factor. The
number of seconds that individuals watched the
screen in the experimental trials did not
influence the likelihood of yawn contagion in
our study, but it is also true that eye-tracking
techniques may better reveal to what extent the
stimulus has been or not observed. The number of
previously observed yawns can influence yawn
contagion in bonobos (Norscia et al., 2022) and
it is not possible to exclude that the stimulus
was more effective in triggering the response in
immature subjects owing to their increased
curiosity toward the videos or the tablet used
to show them. Indeed, immature subjects of
bonobos, chimpanzees, and humans can be more
keen to explore and interact with new objects,
including technological devices (Gruber &
Fandakova, 2021; Kalan et al., 2019). In
autistic children, yawn contagion increases when
the subjects are induced to redirect toward the
video stimulus during experimental trials (Usui
et al., 2013). Further investigation is
necessary to investigate this aspect.
-
- Finally, another interesting aspect that
emerged from the use of two methods is that
familiarity had an apparently opposite effect on
yawn contagion in the two different settings
(naturalistic vs. experimental). An issue that
is relevant to interpret our findings is that we
did not test identical familiarity factors in
the two conditions. Via experimental trials we
were able to test whether yawn contagion was
elicited more by video yawn stimuli coming from
complete strangers (beyond the colony) or by
colony mates whereas via naturalistic data we
could verify&emdash;within the
colony&emdash;whether the yawning responses
varied between "real" individuals that formed
permanent association (always together) or not
(not-always together). While yawn contagion was
enhanced in response to own-colony models
compared to strangers (experimental trials),
within the colony it was highest between
individuals that spent less time together
(naturalistic data). These divergent results are
critical, as the effect of familiarity on yawn
contagion is debated (Palagi et al., 2020). In
humans, yawn contagion is highest in individuals
that are socially closer than others, which may
suggest underlying emotional contagion (Norscia
& Palagi, 2011; Norscia et al., 2016;
Norscia et al., 2020; Norscia et al., 2021a). In
chimpanzees, video trials showed increased
response toward in-group than out-group members
(Campbell & de Waal, 2011) but to our
knowledge the effect of social bond on yawn
contagion within the same group has not been
tested. In bonobos, one naturalistic study found
that socially closer individuals showed highest
levels of yawn contagion (Demuru & Palagi,
2012) whereas no such effect was found in
another naturalistic study (Norscia et al.,
2022). Moreover, no effect was found when
comparing yawning responses to strangers and
familiar models in an experimental study using
video stimuli (Tan et al., 2017). As explained
above with respect to the detection of yawn
contagion over different time windows, also in
this case the high interindividual variability
in yawn contagion presence and rates may in part
explain why results on different bonobo cohorts
are not consistent (Norscia et al., 2022). The
increased yawn contagion between less familiar
bonobo group mates fits with previous findings
on the species. Weakly bonded bonobo females can
engage in the longest socio-sexual contacts
(Annicchiarico et al., 2020) and they can most
likely synchronize on their maximum sexual
swelling (possibly underlying autonomic
contagion), thus enhancing socio-sexual contacts
(Demuru et al., 2022). Finally, the attention of
bonobos is biased toward emotional scenes
depicting unfamiliar bonobos rather than
groupmates (van Berlo et al., 2023). In bonobos
the social system combines clear
in-group/out-group distinction but also
out-group tolerance (Samuni et al., 2022).
Indeed, bonobos react more to calls from
familiar than stranger conspecifics (Keenan et
al., 2016) but during intergroup encounters
certain individuals can socialize with outgroup
members (Cheng et al., 2022). Additionally, the
individuals that cooperate more with in-group
members are also more cooperative with
out-groups (Samuni & Surbeck, 2023).
Interacting with complete strangers versus less
familiar group members is a completely different
experience for bonobos and, in this respect, our
results on familiarity deriving from the
naturalistic and experimental setting are to be
considered as complementary.
-
- The above results prompt interesting
considerations on the relationship among the
motor replication of facial expressions,
socio-emotional cohesion, and ecological
context. Firstly, individuals responded
differently to the same facial expression
(yawning) depending on its contextualization
within the social fabric (naturalistic setting)
versus its absence (experimental setting),
emphasizing the pivotal role of context. The
social intelligence hypothesis contends that
facial expression phenotypes and functions are
tightly connected to socio-ecological context
(Schmidt & Cohn, 2001). Moreover, context
may determine the emotional valence of
expressions that are not inherently negative and
the corresponding response (Kret &
Akyüz, 2022). Yawning in humans is not
inherently negative as it can be associated with
mild stress but also with neutral behavioral
transitions related to the circadian rhythm
(Zilli et al., 2007). From a biological
perspective, we posit that the concept of
valence may not be relevant in relation to
facial expressions per se, as natural selection
favors the most suitable responses in strict
relation with the environment and external
conditions, which influence its nature (Bijlsma
& Loeschcke, 2005). Secondly, the fact that
in the social environment bonobo showed yawn
contagion more frequently between weakly bonded
individuals aligns with the hypothesis that
motor mimicry may reduce prediction errors on
others' behavior (Kret & Akyüz, 2022).
Because the prediction error is supposedly
higher between weakly bonded individuals, its
reduction may be relevant in facilitating the
development of social relationships via
synchronization. Depending on the circumstances,
yawning in response to the yawn of less familiar
individuals may also serve to interrupt, rather
than facilitate, an interaction, as it has been
posited for motor mimicry (Kret &
Akyüz, 2022). Supporting this hypothesis is
the fact that yawning&emdash;as said
above&emdash;can be enhanced by anxiety, stress,
and behavioral transitions, which involve the
interruption of one activity to commence another
(e.g., resting to moving, sleep to wake; Gallup,
2022; Thompson, 2014; Zannella et al., 2015). In
humans, for example, mimicry can lead to lower
levels of trust thus favoring social disruption
(Diana et al., 2023).
-
- In summary, this study cautions against
using singular methods to draw general
conclusions about motor replication phenomena
and suggests that, under certain circumstances,
such phenomena, including yawn contagion, may
promote emotional state synchronization.
Synchronizing with other group members,
especially less familiar ones, is adaptive as
failing to predict others' behaviors and to
coordinate can threaten the survival of both the
group and its members.
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