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les articles sur la contagion du
bâillement
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articles about contagious
yawning
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- Abstract
- Humans express facial mimicry across a
variety of actions. This article explores a
distinct example, contagious yawning, and the
links to empathy and prosocial behavior. Prior
studies have suggested that there is a positive
link between empathy and the susceptibility to
contagious yawning. However, the existing
evidence has been sparse and contradictory. The
authors present results from 2 laboratory
studies conducted with 171 (Study 1) and 333
(Study 2) student volunteers. Subjects were
video-recorded while watching muted videos of
individuals yawning, scratching, or laughing.
Empathy was measured using the Interpersonal
Reactivity Index. Although subjects imitated all
facial expressions to large extents, their
studies show that only contagious yawning was
related to empathy. Subjects who yawned in
response to observing others yawn exhibited
higher empathy values by half a standard
deviation. However, they found no evidence that
the susceptibility to contagious yawning is
directly related to prosocial behavior.
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- Résumé
- Les humains extériorisent leurs
capacités mimétiques des
expressions du visage de nombreuses
façons. Cet article explore un exemple,
la contagion du bâillement, et explore ses
liens avec l'empathie et tente de
déterminer sa nature de comportement
prosocial. Des études antérieures
ont suggéré qu'il existe un lien
positif entre l'empathie et la
susceptibilité à la
réplication du bâillement.
Cependant, les preuves existantes sont peu
nombreuses et certaines contradictoires. Les
auteurs présentent les résultats
de deux études de laboratoire
menées auprès de 171
étudiants volontaires (étude 1) et
333 (étude 2). Les sujets ont
été enregistrés par
vidéo tout en regardant des vidéos
d'individus bâillant, se grattant ou
riant. L'empathie a été
mesurée à l'aide de l'indice de
réactivité interpersonnelle. Bien
que les sujets aient imité toutes les
expressions faciales, ces études montrent
que seul le bâillement contagieux est
lié à l'empathie. Les sujets qui
bâillent en observant les autres
bâiller manifestent des valeurs d'empathie
supérieures d'un demi-écart-type.
Cependant, ils n'ont trouvé aucune preuve
que la susceptibilité au bâillement
soit directement liée au comportement
prosocial.
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- Humans are social beings. They are highly
skilled in interpreting the facial expressions
and gestures of other humans and in re- sponding
to the signals, expectations, and behaviors
encoded in these actions. Some forms of
emotional and behavioral imitation appear
unconsciously and within milliseconds (e.g.,
Chartrand & Bargh, 1999; Dimberg, Thunberg,
& Elmehed, 2000). Other reac- tions are more
conscious and context-dependent (see Hess &
Fischer, 2013, for a recent review). Both
strands of the literature have suggested that
mimicry, be it conscious or unconscious,
facilitates social cohesion and coordination in
groups (e.g., Lakin, Jefferis, Cheng, &
Chartrand, 2003). The existing evidence has
suggested that mimicry works in two ways: First,
the mimickee infers from the imitation of his
behavior or gestures that others understand his
intentions or emotions. Second, the mimicker en-
hances his empathy with the person he imitates.
Thus, Stel, Van Baaren, and Vonk (2008) showed
that subjects who were in- structed to mimic
others also have higher levels of empathy for
the imitated person. Hence, mimicking others can
elevate empathy, which in turn increases
prosocial behavior even toward others not
related to the mimicking.
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- Also, the relation between empathy and
prosocial behavior has been much discussed in
the literature (Batson, 1991; Batson &
Moran, 1999; de Waal, 2012; Eisenberg &
Miller, 1987; Galinsky, Maddux, Gilin, &
White, 2008; Stocks, Lishner, & Decker,
2009). Some authors have suggested that empathy
is an unpleasant emo- tion (e.g. Batson, 1991).
One way of reducing it is to either escape
situations in which empathy emerges or help
those in need. This hypothesis has been termed
the aversivearousal reduction hy- pothesis
(Batson, 1991). According to the hypothesis,
prosocial behavior is basically a selfish
response. An alternative mechanism is that
empathy highlights an altruistic perspective. So
far, most evidence has supported this
empathyaltruism hypothesis (Doris & Stitch,
2007; Nichols, 2004; Stocks et al., 2009). In
this article, we focus on a distinct and
peculiar phenom- enon of mimicry, namely the
contagiousness of yawning. Hu- mans, like most
vertebrates, yawn occasionally.
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- The existing evidence has suggested that it
is induced by sleepiness (e.g. Provine, 2005).
Yawning increases the oxygen content of the
blood and lowers the brain temperature,
functioning as a wake-up call (Gallup &
Gallup, 2007, 2008; Guggisberg, Ma- this,
Schnider, & Hess, 2011; Provine, 2005;
Zilli, Giganti, & Uga, 2008). However,
yawning can also be contagious. Former studies
have suggested that about 40% to 60% of humans
are susceptible to contagious yawning (e.g.,
Gallup, Church, Miller, Risko, & Kingstone,
2016), and there is also evidence that it is
contagious among some animals, like chimpanzees,
dogs, and wolves (e.g., Romero, Ito, Saito,
& Hasegawa, 2014; Romero, Konno, &
Hasegawa, 2013). Moreover, some studies have
suggested that the susceptibility of contagious
yawning is linked to the degree of empathy
(Lehmann, 1979; Norscia et al., 2016b; Palagi,
Leone, Mancini, & Ferrari, 2009; Provine,
1986, 2005). For instance, Platek, Critton,
Myers, and Gallup (2003) found that individuals
who are more sensitive to contagious yawning
also recognize social faux pas in written
reports better than do subjects who are not
susceptible to it. Yawning is also more
contagious among individuals with close social
ties, compared to strangers (Nors- cia, Demuru,
& Palagi, 2016b; Norscia & Palagi, 2011;
Palagi, Norscia, & Demuru, 2014). Moreover,
Haker and Rössler (2009) found that
individuals with schizophrenic disorders are
less sensitive to contagious yawning and also
display lower empathy values compared to healthy
individuals.
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- Further evidence stems from studies in
neuroscience that use functional magnetic
resonance imaging. These results suggest that
the urge to yawn when observing others yawning
is related to neural activity in those areas of
the brain that are involved in assessing
self-referent information (Arnott, Singhal,
& Goodale, 2009; Brown et al., 2017; Cooper
et al., 2012; Haker, Kawohl, Her- wig, &
Rössler, 2013; Platek, Mohamed, &
Gallup, 2005). To sum up, research so far has
suggested that asking indi- viduals to imitate
others elevates their empathy and that empa- thy
in turn increases prosocial behavior. In this
article we investigate a slightly different
question. We study the link of contagious
yawning and empathy if researchers do not
actively encourage the mimicry. Hence, we
investigate whether the susceptibility of
contagious yawning is also an indicator of
individuals' baseline empathy level. Some
existing evidence on contagious yawning has
suggested this link. However, other studies have
shown counterevidence.
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- Particularly, a study by Bartholomew and
Cirulli (2014) using 328 subjects found no
evidence that contagious yawning is related to
empathy. Be- sides its comparatively large
sample, the study by Bartholomew and Cirulli has
the advantage of measuring empathy directly via
the Interpersonal Reactivity Index (IRI),
whereas studies reporting positive evidence
relied on indirect measures such as the faux-pas
test or the auxiliary assumption that empathy is
higher among closer social ties. But Bartholomew
and Cirulli's (2014) study also has some
disadvantages. First, subjects had to
self-report whether they yawned. Measuring
yawning by self-report has the disadvan- tage of
leaving the measurement to the subjects and
their interpretation and thus withdraws it from
the control of the experimenter. Second, the
experimenters informed subjects of the
phenomenon of contagious yawning before they
partici- pated in the study, which may have
stimulated the social desir- ability of
contagious yawning. Yawning was reported by 67%
of their subjects, which is a higher incidence
of yawning than reported in other studies. The
high incidence could have obscured the
difference between yawners and nonyawners with
respect to empathy. Furthermore, Bartholomew and
Cirulli did not use any control group in their
study. Therefore, it remains unclear what the
rate of yawning would have been if subjects had
watched other stimulus videos of nonyawning
faces. This makes the distinction between
yawning that occurs spontane- ously and yawning
that occurs due to contagion impossible.
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- Taken together, the empirical evidence on
whether conta- gious yawning is related to
empathy is still unclear, and the existing
evidence contradictory (e.g., Massen &
Gallup, 2017). Studies that found positive
evidence did not employ direct measurements of
empathy (e.g., by using the IRI), and the study
that found no evidence (Bartholomew &
Cirulli, 2014) used a weak measure of the
occurrence of contagious yawning. To gain
further insight into the phenomenon of
contagious yawning and its relation to empathy,
we conducted two studies with large samples of
healthy volunteers. Study 1 was conducted in a
manner very similar to that in the Bartholomew
and Cirulli (2014) study. However, we videotaped
subjects while they were watching the stimulus
videos and coded the occurrence of yawning from
these videos. Because prior studies have pro-
posed that empathy is an important prerequisite
of altruism and prosocial behavior (Batson &
Moran, 1999; de Waal, 2012; de Waal &
Preston, 2017; Eisenberg & Miller, 1987;
Galinsky et al., 2008; Stocks et al., 2009), we
extend the existing literature on contagious
yawning by also investigating whether it is
directly related to prosocial behavior.
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- In Study 1, the test consisted of a dictator
game in which subjects had the oppor- tunity to
donate some (or all) of their endowment to an
anonymous recipient. Because Study 1 also did
not involve a control group, we conducted a
second study, in which subjects were randomized
into either a treatment group or a control
group. In the treatment group, subjects watched
videos of laughing faces, people scratching or
touching their face or hair, and yawning faces.
In the control group, subjects watched only
laughing and scratching subjects. This
experimental procedure allowed us to determine
the natural occurrence of spontaneous yawning in
comparison to contagious yawning. Moreover, it
also allowed us to test whether other forms of
mimicry (scratching and laughing) are related to
empathy.
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- We also measured prosocial behavior in Study
2 by giving subjects the opportunity to donate
some (or all) of their experimental payment to a
charitable organization. Summing up, we
investigated three hypotheses: Hypothesis A
postulates that empathy is positively related to
prosocial behavior. Hypothesis B suggests that
empathy varies among individuals and that the
susceptibility of contagious yawning is an
indicator of empathy. Hypothesis C suggests that
those who show contagious yawning also more
likely show prosocial behavior. The remainder
of the article proceeds in as
follows: First, we describe the method used
in Study 1, followed by the results. Then we
discuss the limitations of Study 1 and describe
the method used in Study 2, which responds to
the limitations of Study 1 and extends the
existing evidence. Specifically, Study 2
investigates whether other forms of facial
mimicry are also indicators of empathy. Then we
report the results of Study 2. Finally, the
results of both studies are summarized and
discussed.
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- Discussion
- This study found clear evidence that
susceptibility to contagious yawning is related
to empathy. In Study 1, 24% of the subjects
yawned, and yawning subjects showed higher
empathy values by .49 standard deviation when
compared to nonyawning subjects. This result was
closely replicated in Study 2, in which 22% of
the subjects yawned in response to the stimulus
video. Our finding confirms results of previous
research, which showed indirect evi- dence of
yawning's being related to empathy (Arnott et
al., 2009; Norscia et al., 2016b; Norscia &
Palagi, 2011; Palagi et al., 2014; Platek et
al., 2003, 2005), and disconfirms the missing
evidence reported by Bartholomew and Cirulli
(2014). We believe that the association between
contagious yawning and empathy was ob- scured in
the Bartholomew and Cirulli study for
methodological reasons. The authors informed
subjects beforehand about the nature of
contagious yawning, and they relied on the
subjects' self-reporting to measure the
occurrence of yawning.
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- In contrast, we recorded the subjects on
video and thus have a more objective and
reliable measure of the occurrence of yawning.
The contagion rate of 24% that we found is
comparatively low. One reason for this might be
that subjects watched the stimulus videos while
other subjects were also present in the
laboratory. All workplaces were separated by
cubicles in such a way that subjects' faces were
not directly observable by other subjects.
However, the mere presence of others in the same
room might have inhibited contagious yawning, as
suggested by Gallup et al. (2016). Furthermore,
Study 2 shows that other mimicry, for example,
face scratching or laughing, is not an indicator
of empathy. This finding is not in contradiction
with the results of Stel et al. (2008), who
instructed subjects to imitate others and found
elevated em- pathy levels afterward. But our
results suggest that the simple occurrence of a
smile while watching others smile or laugh is
not an indicator of empathy, as is contagious
yawning. Taken together, these results suggest
that contagious yawning is a special and
distinct phenomenon. It is hard to control and
seems to be biolog- ically ingrained in highly
social species, such as monkeys, apes, and
humans. Highly social species must often rely on
the synchro- nization of behavior, particularly
in situations of escaping from predators,
coordinating sleepwake cycles, or adhering to
social norms. Hence, it might have been
evolutionarily advantageous to be highly
susceptible to the emotions and intentions of
others, and authors like de Waal (2008) have
suggested that empathy provides the basis for
synchronized motor action and synchronizes emo-
tional states. This, in turn, has positive
feedback effects on social cohesion (Palagi et
al., 2009; Seyfarth & Cheney, 2013) and
promotes helping behavior and
identification with conspecifics (Preston
& de Waal, 2002).
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- Our study found positive evidence for only
Hypotheses A and B and not for Hypothesis C,
that contagious yawning has a direct link to
prosocial behavior. Yawning subjects did donate
more money to an anonymous recipient in the
dictator game (Study 1). However, the difference
between yawners and nonyawners was not statisti-
cally significant. The same results held true
with respect to donat- ing to a charitable
organization (Study 2). Hence, contagious
yawning is a signal of empathy, but the signal
is not very strong or clear. However, using a
measure of general empathy and general prosocial
behavior (as we did) does not take context into
consid- eration. The relation between contagious
yawning and prosocial behavior might indeed be
stronger if the prosocial behavior is specific
and directed toward members of one's own group.
- Moreover, the degree of empathy is also
determined by other factors such as gender (as
also shown by our results) or presum- ably
through education and socialization (not tested
here). Norscia et al. (2016b) and Chan and Tseng
(2017) reported that female subjects were more
susceptible to contagious yawning. Also, in our
studies, women were more susceptible to
contagious yawning (24.4%) than were men
(19.6%). However, this difference is not
statistically significant, 2(1, N 354) .97, p
.32, confirming the results of various other
studies (e.g., Gallup & Massen, 2016).
However, the IRI shows clearly higher values for
women. Hence, we also conclude that women are
more empathetic than are men, presumably because
women are "hard-wired for maternity and parental
care" (Norscia et al., 2016b, p. 1; for a
detailed discussion of the gender effect, see
also Norscia, Demuru, & Palagi, 2016a).
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- It is interesting that, and not easily
explained why, only conta- gious yawning, and
not scratching or laughing, was related to
empathy in our study. One interpretation is that
scratching, and more so laughing, are more
easily controllable behaviors. Individ- uals
might have learned that it is socially expected
to imitate a smile or laugh. However, yawning is
much harder to control or to suppress, and it is
therefore harder to be shaped by cultural
factors. We believe that the study results
represent an important finding and indicate
avenues for further research. First,
susceptibility to contagious yawning seems to be
an implicit test of empathy. Second, the finding
that contagious yawning is not generally related
to prosocial behavior raises questions about
whether this association can be found in groups
of closer social ties (e.g., as parochial
prosocial behavior) along the lines suggested by
De Dreu et al. (2010).
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