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Duchenne Smile, Emotional Experience, and Autonomic Reactivity. A Test of the Facial Feedback Hypothesis

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This study examined the modulatory function of Duchenne and non-Duchenne smiles on subjective and autonomic components of emotion. Participants were asked to hold a pencil in their mouth to either facilitate or inhibit smiles and were not instructed to contract specific muscles. Five conditions--namely lips pressing, low-level non-Duchenne smiling, high-level non-Duchenne smiling, Duchenne smiling, and control--were produced while participants watched videoclips that were evocative of positive or negative affect. Participants who displayed Duchenne smiles reported more positive experience when pleasant scenes and humorous cartoons were presented. Furthermore, they tended to exhibit different patterns of autonomic arousal when viewing positive scenes. These results support thefacial feedback hypothesis and suggest that facial feedback has more powerful effects when facial configurations represent valid analogs of basic emotional expressions.
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Duchenne Smile, Emotional Experience, and Autonomic
Reactivity: A Test of the Facial Feedback Hypothesis
Robert Soussignan
Hoˆpital de la Salpeˆtrie`re
This study examined the modulatory function of Duchenne and non-Duchenne
smiles on subjective and autonomic components of emotion. Participants were
asked to hold a pencil in their mouth to either facilitate or inhibit smiles and were
not instructed to contract specific muscles. Five conditions—namely lips pressing,
low-level non-Duchenne smiling, high-level non-Duchenne smiling, Duchenne
smiling, and control—were produced while participants watched videoclips that
were evocative of positive or negative affect. Participants who displayed Duchenne
smiles reported more positive experience when pleasant scenes and humorous
cartoons were presented. Furthermore, they tended to exhibit different patterns of
autonomic arousal when viewing positive scenes. These results support the facial
feedback hypothesis and suggest that facial feedback has more powerful effects
when facial configurations represent valid analogs of basic emotional expressions.
The human face has long been recognized as a
powerful signaling system serving both inter- and in-
traindividual regulatory functions. Implicit in such a
view is the assumption that facial behavior constitutes
not only the expressive output of inner emotional
states or social motives but also an input to the sub-
jective experience of emotion. The idea that afferent
feedback from expressive behavior may play a causal
role in the experience of emotion takes its roots in part
from Charles Darwin’s and William James’s state-
ments. Darwin (1872/1965) claimed that the intensity
of emotional experience could be regulated by en-
hancing or inhibiting the expression, whereas James
(1890) proposed that subjective feeling was the result
of peripheral bodily changes (i.e., visceral and striated
muscle activity) that directly follow the perception of
the eliciting event. The influence of these views can
be seen in more recent theories of emotion, which
assign to facial expression a primary role in the sub-
jective experience of emotion (Izard, 1971; Tomkins,
1962). This gave rise to the so-called facial feedback
hypothesis (FFH), which stated that facial movement
could influence emotional experience (Tourangeau &
Ellsworth, 1979).
In the course of empirical investigation of the FFH,
several variants of this hypothesis have been distin-
guished. First, Tourangeau and Ellsworth (1979)
raised three questions derived from the FFH: (a) Is an
appropriate facial expression necessary for the sub-
jective experience of emotion? (necessity hypothesis);
(b) Is a facial expression sufficient to produce an emo-
tional experience, even in the absence of an evocative
event? (sufficiency hypothesis); and (c) Does the
strength of a facial expression covary positively with
the intensity of emotional experience? (monotonicity
hypothesis). Whereas the view that facial displays are
necessary for experiencing emotion has not been sup-
ported (e.g., Ferna´ndez-Dols & Ruiz-Belda, 1995;
Hess, Kappas, McHugo, Lanzetta, & Kleck, 1992),
there is substantial evidence in favor of the suffi-
ciency and monotonicity hypotheses (see Hess et al.,
1992; McIntosh, 1996).
Although the several variants of the FFH do not
necessarily imply causality between face and emo-
tion, they all postulate that facial action can initiate
(sufficiency hypothesis) and/or modulate the subjec-
tive experience of emotion (Adelmann & Zajonc,
1989; McIntosh, 1996). The initiation hypothesis
I thank Nathalie Fontaine for her assistance in the data
collection. I am grateful to Patrick Mollaret for helpful com-
ments concerning the design of this research. I also thank
Paul Gendreau, Benoist Schaal, and Rita Compatangelo for
valuable comments on an earlier version of this article.
Correspondence concerning this article should be ad-
dressed to Robert Soussignan, Laboratoire Vulne´rabilite´,
Adaptation et Psychopathologie, CNRS UMR 7593, Pavil-
lon Cle´rambault, Hoˆpital de la Salpeˆtrie`re, 47, Bd de
l’Hoˆpital, 75013 Paris, France. E-mail: soussign@ext.
jussieu.fr
Emotion Copyright 2002 by the American Psychological Association, Inc.
2002, Vol. 2, No. 1, 52–74 1528-3542/02/$5.00 DOI: 10.1037//1528-3542.2.1.52
52
states that affective experience can be generated by
facial displays, even in the absence of an emotional
stimulus. The modulation hypothesis, as postulated by
Darwin, simply stipulates that facial displays (e.g.,
intensifying or inhibiting a facial expression) may al-
ter the intensity or the quality of the ongoing emo-
tional experience.
An additional distinction between dimensional and
categorical versions of the FFH has been suggested
(Winton, 1986). According to the so-called weak ver-
sion, facial movements may produce changes in self-
reports of emotional experience on a positive–
negative dimension. According to the so-called strong
version, movements of the face may foster more dif-
ferentiated emotional experience, such as enjoyment,
anger, fear, and sadness.
The distinct versions and variants of the FFH typi-
cally have been tested by manipulating facial effer-
ence by means of two paradigms: (a) by asking par-
ticipants to display facial configurations that represent
particular emotional expressions (i.e., facial-posing
procedure/muscle-by-muscle instruction) with or
without an emotional stimulus (Duclos et al., 1989;
Hess et al., 1992; Laird, 1974; Rutledge & Hupka,
1985; Tourangeau & Ellsworth, 1979); (b) by asking
participants to exaggerate or suppress facial displays
(exaggeration/suppression procedure) normally ex-
pected in response to a wide range of affective–
eliciting events, such as electric shocks, videotapes,
odors, or mental imagery (Colby, Lanzetta, & Kleck,
1977; Kleck et al., 1976; Kraut, 1982; Lanzetta, Cart-
wright-Smith, & Kleck, 1976; McCanne & Anderson,
1987; Zuckerman, Klorman, Larrance, & Spiegel,
1981).
Numerous experimental investigations focusing on
the modulating function of facial expression within a
dimensional perspective have generally demonstrated
moderate but reliable effects of voluntary facial ac-
tivity on self-reported emotional experience and, to
some extent, on autonomic response patterns (for re-
views see Adelmann & Zajonc, 1989; Laird, 1984;
Manstead, 1988; Matsumoto, 1987; McIntosh, 1996;
Winton, 1986). Concerning the categorical version of
FFH, despite some contradictory findings (Tou-
rangeau & Ellsworth, 1979), evidence has now accu-
mulated suggesting that adopting a requested facial
pattern of emotion (e.g., fear, anger, disgust, sadness,
happiness) may induce a feeling of this particular
emotion, even in the absence of any eliciting event.
(Duclos et al., 1989; Duclos & Laird, 2001; Flack,
Laird, & Cavallaro, 1999; Hess et al., 1992; Leven-
son, Ekman, & Friesen, 1990; Levenson, Ekman,
Heider, & Friesen, 1992). Finally, although the issue
of autonomic differentiation within the categorical
version of FFH has provided a lower degree of con-
sistency (see Boiten, 1996; Cacioppo, Klein, Bernt-
son, & Hatfield, 1993), muscle-by-muscle manipula-
tion or posing a particular facial expression have been
shown to induce changes in heart rate, electrodermal
activity, and peripheral temperature (Ekman, Leven-
son, & Friesen, 1983; Hess et al., 1992; Levenson et
al., 1990, 1992).
Because of a number of methodological problems,
the cognitive and physiological mechanisms underly-
ing the facial regulation of affective states are far from
being understood (Buck, 1980; Larsen, Kasimatis, &
Frey, 1992; Strack, Martin, & Stepper, 1988; Zajonc,
Murphy, & Inglehart, 1989). Some authors have sug-
gested that sensory input (i.e., muscular propriocep-
tive patterns and/or cutaneous sensations) or vascular
changes (i.e., thermoregulation of cerebral arterial
blood flow) are possible physiological mediators
(Izard, 1990; McIntosh, Zajonc, Vig, & Emerick,
1997; Tomkins, 1962; Zajonc et al., 1989). Others
have postulated that feeling states may derive from
the self-perception of expressive behavior and that
individuals may have the ability to interpret their mus-
cular proprioceptive sensation as representative of
their subjective experience (Laird, 1974).
Strack et al. (1988) pointed out that standard pro-
cedures of experimenter-manipulated expressions
(i.e., facial posing and dissimulation/exaggeration
paradigms) do not rule out ambiguities and experi-
mental artifacts due to situational demands (see also
Rutledge & Hupka, 1985). In particular, these authors
argued that these procedures are possibly contami-
nated by a cognitive mediation (e.g., attribution pro-
cesses, redirection of attention, recognition of the
emotional meaning of facial behavior, category ac-
cessibility), thus making difficult to assess the possi-
bility of physiologically driven mechanisms. To
clarify the processes that mediate the facial feed-
back effect, an ingenious procedure minimizing the
likelihood that participants make inferences about
their subjective experience of emotion was designed.
According to this procedure participants (a) did not
have to pose or modify a required facial expression,
(b) redirected their attention toward another task, and
(c) activated only the muscles typically involved in
an expression. A plausible cover story was used to
distract the participants’ attention toward their own
facial displays. The participants were told that the
objective of the study was to investigate the ability of
injured or handicapped persons to perform different
DUCHENNE SMILE AND EMOTIONAL EXPERIENCE 53
tasks with different parts of their body. Specifically,
in Study 1, they were instructed to hold a pen in their
teeth (facilitating the production of smiling because of
the contraction of zygomaticus major muscle), in their
lips (inhibiting the smile because of the contraction of
orbicularis oris muscle), or in their nondominant
hand, while they rated the funniness of cartoons. In
Study 2, they were asked to differentiate between the
funniness of the cartoons and the amusement feeling
induced by them. Using task difficulty as a covariate,
the authors found that the unconscious facilitation of
smiling behavior led the participants to rate the car-
toons as being funnier, whereas inhibiting the muscu-
lar activity associated with smiling dampened their
funniness ratings (Study 1). Furthermore, when par-
ticipants were given the opportunity to distinguish
between the two measures of the humor response, a
facial feedback effect was reported for the amusement
ratings only (Study 2). From these results, the authors
concluded that cognitive mediation (i.e., self-
perception process and recognition of the emotional
meaning of facial expressions) is not necessary to in-
fluence the experience of emotion.
Because of a variety of methodological limitations,
the research conducted by Strack et al. (1988) is not
entirely conclusive. First, it is unclear whether the
facilitating influence of smiling on emotional experi-
ence specifically was due to facial muscle feedback.
Indeed, the authors did not examine whether their
pen-holding conditions were related to differences in
pleasantness of the task. Thus, this leaves open the
possibility that the funniness ratings of the cartoons
(Study 1) or the amusement ratings (Study 2) they
evoked may have been contaminated by differences of
affective conditions between the pen-holding tech-
niques.
A second problem with Strack et al.’s (1988) re-
search concerns the definition of their facial control
condition (i.e., holding the pen with lips induces lips
pressing). This condition causes the contraction of a
muscle (i.e., orbicularis oris) involved in the expres-
sion of anger (Ekman & Friesen, 1975; Ekman,
Friesen, & O’Sullivan, 1988). Accordingly, the ques-
tion arises as to whether differences in amuse-
ment ratings detected in their study were not contami-
nated by the potentially negative effect of the orbicu-
laris oris activity. An adequate facial control for test-
ing the specific effect of smiling on positive affect
would be to use a neutral face or a face without the
presence of muscle action associated with a negative
emotion.
Another limitation of Strack et al.’s (1988) studies
concerns the choice of criteria used to represent the
requested facial expression. This requires that the ex-
perimenter-manipulated facial expression (a) recruits
only patterns of facial muscles reported from the em-
pirical research on basic emotions, (b) meets certain
criteria with regard to intensity and duration of mus-
cular actions, and (c) does not contain extraneous
muscle movements generated by the presence of emo-
tional stimuli (Hager & Ekman, 1981; Matsumoto,
1987). In their studies, the lack of recording and mea-
surement of actual facial behavior while participants
were exposed to cartoons raises questions about the
comparability of participants’ data, both across and
within pen-holding tasks. More particularly, because
facial expression may change as a function of a num-
ber of parameters (e.g., intensity, duration, recruit-
ment of additional actions), it appears important to
verify that the muscular movements produced are ex-
actly the same as those requested.
Finally, regarding the issue of the quality of smil-
ing, Strack et al.’s (1988) studies focused only on the
manipulation of zygomatic major action, whereas re-
search findings highlighted that distinguishing among
morphologically different types of smiles may be heu-
ristically relevant (Dickson, Walker, & Fogel, 1997;
Ekman, Davidson, & Friesen, 1990; Ekman et al.,
1988; Fox & Davidson, 1988; Messinger, Fogel, &
Dickson, 2001; Soussignan & Schaal, 1996b). More
particularly, a distinction has been made between the
basic smile, which recruits only zygomaticus major
muscles, and the Duchenne smile, which involves the
simultaneous activation of zygomaticus major and or-
bicularis oculi. The latter muscles raise the cheeks and
wrinkle the outside corners of eyes (Duchenne, 1862/
1990; Ekman, 1989). Because smiles with Duch-
enne’s marker (i.e., the presence of orbicularis oculi
activity) have been more often associated with the
experience of positive emotions (e.g., amusement) in
comparison with other forms of smiling (Ekman et al.,
1990), their experimental manipulation may be useful
in determining whether stronger peripheral feedback
effects are specifically related to some prototypical
facial patterns.
Duchenne Smiling and Emotional Experience
Although it is widely accepted that smiling pro-
vides salient communicative signals for regulating so-
cial exchanges, the view that smiling can be seen as a
readout of inner positive emotions is somewhat con-
troversial. Observational and psychophysiological
studies have shown that activity of zygomaticus major
SOUSSIGNAN54
is correlated to the perception of a wide range of
pleasant stimuli (Cacciopo, Petty, Losch, & Kim,
1986; Dimberg, 1982; Ekman, Friesen, & Ancoli,
1980). Conversely, a number of reports indicated that
positive emotional states (e.g., pleasure, happiness)
alone are neither sufficient nor necessary to produce
smiles (Ferna´ndez-Dols & Ruiz-Belda, 1997; Frid-
lund, 1994). In addition, smiling may occur in various
social contexts wherein there may be little positive
feeling (e.g., conversation, submissiveness, embar-
rassment) or may be also related to ongoing negative
emotion during deceitful interactions (Ekman et al.,
1988; Fridlund, 1991; Keltner, 1995; Kraut & Johns-
ton, 1979; Lafrance & Hecht, 1999; Provine &
Fischer, 1989; Soussignan & Schaal, 1996a). Thus,
available data suggest that the correspondence be-
tween smiling and positive feelings is far from clear.
To clarify this issue, Ekman and Friesen (1982)
suggested that variants of human smile could be dis-
tinguished on the basis of a number of behavioral
markers (i.e., morphology, intensity, timing, location,
laterality). More particularly, “felt/enjoyment” (or
Duchenne) smiles have been distinguished from
“false” (or non-Duchenne) smiles on the basis of the
presence of orbicularis oculi activation, as marked by
crow’s feet wrinkles in the eye region (Ekman, 1989;
Ekman & Friesen, 1982). Several studies have ob-
tained evidence that Duchenne smiles occurred more
often than other types of smiling when adult partici-
pants watched pleasant films or when they self-
reported amusement during both solitary and social
situations (Ekman et al, 1990; Ekman & Friesen,
1982; Frank, Ekman, & Friesen, 1993). In infants,
Duchenne smiles are more often displayed at the ap-
proach of their mother rather than a stranger or during
mother–infant–object play (Dickson et al., 1997; Fox
& Davidson, 1988). In school-age children, they are
shown more frequently during success than they are in
failure in a game (Schneider & Unzner, 1989). Other
studies have also revealed that compared with other
forms of smiling, Duchenne smiles (a) are of greater
intensity, (b) differ in dynamic markers and social
signal value, (c) induce empathy, and (d) are corre-
lated with a distinct pattern of regional electroen-
cephalographic activation (Davidson, Ekman, Saron,
Senulius, & Friesen, 1990; Ekman et al., 1990; Fox &
Davidson, 1988; Frank et al., 1993; Soussignan &
Schaal, 1996b; Surakka & Hietanen, 1998).
In sum, although experience of pleasure or enjoy-
ment is not necessarily linked to the expression of
smiles (e.g., Ferna´ndez-Dols & Ruiz-Belda, 1995),
available data support the view that it is heuristically
useful to make a distinction between Duchenne and
non-Duchenne smiles, as they have distinct experien-
tial, situational, and cerebral correlates.
Aims of the Present Study
The questions raised by Strack et al.’s (1988) study
led us to design a study targeting three major objec-
tives. The first objective was to replicate and extend
their work by examining more stringently the facili-
tating influence of manipulated zygomatic action on
self-reported emotional experience and autonomic
nervous system activity. The integration of autonomic
parameters is relevant as they are less susceptible to
demand characteristics than are self-report data. We
used a variation of Strack et al.’s pen-holding proce-
dure with two additional groups (i.e., faces without
emotional actions and faces with Duchenne’s
marker). In addition, potentially confounding factors
such as task unpleasantness and task difficulty were
controlled for. During a pencil-holding task, partici-
pants’ faces were filmed while they were shown both
negative and positive videoclips. This procedure was
used to control for the methodological issues men-
tioned above (i.e., use of a valid analog of emotion,
selection of faces with the requested actions, control
of intensity and duration of movements). A replica-
tion of Strack et al.’s study would strengthen the hy-
pothesis that cognitive mediation, but also potential
confounding factors such as task unpleasantness,
lacks of adequate facial control, and presence of ad-
ditional actions do not explain the facial effects ob-
served.
The second objective of the present study was to
test whether distinct patterns of smiles (non-
Duchenne smile vs. Duchenne smile) differentially
influenced subjective and autonomic responding. A
greater facilitating effect of Duchenne smiles on both
subjective and autonomic responses was expected be-
cause correlational studies have demonstrated their
strong relationship with positive emotions. More spe-
cifically, we examined two issues. First, in accor-
dance with the monotonicity hypothesis, we predicted
that the strength of smile (Duchenne vs. non-
Duchenne) would positively covary with the intensity
of emotional experience and physiological arousal.
This hypothesis was tested because Duchenne smiles
are typically associated with greater zygomatic inten-
sity (Frank et al., 1993). Second, in comparing Du-
chenne smiles to non-Duchenne smiles of similar zy-
gomatic intensity, we wanted to examine whether the
morphology of smiling (due to the presence of orbi-
DUCHENNE SMILE AND EMOTIONAL EXPERIENCE 55
cularis oculi action) would increase the subjective and
physiological reactions associated with various emo-
tional stimuli. This hypothesis was explored because
it has been suggested that feedback effects should be
stronger when facial configurations most closely
match pure emotional expressions (Hager & Ekman,
1981; Levenson et al., 1990).
Finally, we focused on some stimulus parameters
(e.g., valence, intensity) under which the facial effects
would be most powerful. A number of psychophysi-
ological studies reported that both intensity and va-
lence of affective stimuli potentiated facial electro-
myographic (EMG) activity (Cacioppo, Bush, &
Tassinary, 1992; Cacioppo et al., 1986; Greenwald,
Cook, & Lang, 1989). For instance, EMG activity
over the cheek (zygomaticus major) and the periocu-
lar (orbicularis oculi) muscle regions tended to be
higher when pleasant scenes were presented. Further-
more, EMG activity over the orbicularis oculi muscle
differentiated between moderately and mildly positive
conditions (Cacioppo et al., 1986). Thus, we wanted
to know whether feedback effects from specific pat-
terns of smiles would be constrained by both the con-
gruity (i.e., related to positive stimuli) and intensity
value (i.e., relative to intense emotional experience)
of the stimulus used. More specifically, we examined
whether the potentially modulating effects of Du-
chenne smiling would be better predicted by stimuli
that were evocative of highly positive affect (e.g.,
funny cartoons).
Method
Participants
Ninety-six female undergraduates participated in
this study as part of a psychophysiological course
requirement. Only female participants were chosen
because of large difference of gender ratio in this
course (women–men ratio 10:1). They ranged in
age from 21 to 28 years. Participants were randomly
assigned to four conditions (i.e., control, lips pressing,
non-Duchenne smiling, Duchenne smiling). The ran-
domization design was performed so that each par-
ticipant was drawn from the population before the
study began, with a total of 24 participants per con-
dition. Thus, each participant was a priori assigned to
one of the four groups.
Stimulus Selection
The stimulus materials used were eight 10-s silent
video records. The video excerpts were chosen from a
large sample of 28 videotaped items (e.g., landscapes,
animals, cartoons, mutilated body) intended to induce
both moderate and strong negative or positive affect.
This preliminary rating was conducted on 20 female
undergraduates ranging in age from 19 to 27 years.
Prior to the experiment, they were told that their sub-
jective emotional reactions to various videoclips
would be studied. After viewing each videotaped
scene, the judges were asked to rate their emotional
reactions on a scale ranging from −9 (very negative)
to9(very positive) and then to report dichotomously
whether they found the positive stimulus as either
pleasant or funny. This qualitative description of va-
lence was asked only in the selection procedure. It
was intended to ensure that the selected cartoons were
really funny. The results revealed that cartoons tended
to evoke the strongest self-reported positive reactions
and were judged as funny. Stimuli such as landscapes
and young animals induced weak or moderate positive
experience and were judged pleasant. Because our
aim was to measure whether the potentially facilitat-
ing effects of smiling were better predicted by stimuli
that are evocative of highly positive affect (e.g., car-
toons), we selected stimuli that induced positive or
negative emotional experience with different degrees
of intensity. The mildly positive scenes were a lake
landscape (M 4.00, SD 2.51) and a baby chim-
panzee on a tree (M 4.80, SD 2.87), whereas the
more strongly positive scenes consisted of cartoons
taken from the Tex Avery (M 5.68, SD 3.31) and
Tom & Jerry series (M 7.65, SD 1.39). A cut-off
criterion of 5 was used to classify the stimuli as
evocative of mildly or strongly positive emotional re-
actions. A two-way repeated-measures analysis of
variance (ANOVA), with Intensity and Stimulus as
within-subject factors, indicated that the judges re-
acted more positively to cartoons (M 6.67, SD
1.41) than to videoclips representing the landscape
and the chimpanzee (M 4.42, SD 1.58), F(1, 19)
97.40, p < .001. Similarly, on the negative pole, the
judges reacted more negatively to some videoclips
than to others. The mildly unpleasant scenes por-
trayed a vampire bat sucking the blood of a hen (M
−3.30, SD 2.88) and ants moving on caterpillar
larvae (M −4.90, SD 3.02). Finally, the two
most unpleasant scenes consisted of a physician ex-
amining a child whose toes were amputated (M
−6.95, SD 2.06) and a person scraping and stretch-
ing the skin of a dead animal (M −7.25, SD
2.27). A cut-off point of 5 was used to classify the
stimuli as inducing mildly or strongly negative emo-
tional reactions. A two-way ANOVA (Intensity ×
Stimulus) revealed that the judges responded more
negatively to the videoclips showing amputated toes
SOUSSIGNAN56
and a scraped animal (M −7.10, SD 1.59) than
to those showing the bat and ants (M −4.10, SD
2.46), F(1, 19) 29.48, p <.0001.
Apparatus and Psychophysiological Recording
The autonomic measures (i.e., skin conductance,
heart rate, respiratory rate, bodily temperature) were
continuously monitored using a 4-channel MacLab
system (ADInstruments Pty Ltd.; Castle Hill, New
South Wales, Australia), which was connected to a
Macintosh computer. The bioelectrical signals were
filtered and amplified before being fed into the analog
input connector of the MacLab hardware unit and
sampled at a rate of 20 points/s under the on-line
control of the MacLab application program (Chart
3.5.2. software).
Heart rate was measured using Ag/AgCl electrodes
and a standard Lead II electrode configuration. A low-
pass filtering of 50 Hz was used with the bioamplifier
to eliminate high-frequency components. A computed
input command allowed a threshold control to detect
R wave pulses.
Skin conductance level was recorded using a con-
ducting gel and Ag/AgCl electrodes attached with a
Velcro strap on the volar surface of the distal phalan-
ges of the second and third fingers of the right hand.
An UFI Bioderm skin conductance coupler (model
2701; Morro Bay, CA) provided a constant 0.5 V
across electrodes, and the sensitivity was set at 250
mV/mho.
Respiratory rate changes were recorded by a solid-
state transducer (UFI model 1132 Pneumotrace;
Morro Bay, CA) strapped around the thoracic region.
The piezoelectric device of the pneumobelt responded
linearly to changes in elongation generating a positive
voltage as its length increased.
Bodily temperature was recorded through a type-T
thermocouple sensor (time constant: 0.3 s, resolution:
0.1°C) insulated in a 1.3 mm diameter Teflon lead.
The sensor was placed on the medial part of the fore-
head and connected—via a Bat-10 thermometer—to
the computer-based data acquisition system for direct
temperature readings. A 50-Hz low-pass signal filter-
ing was selected to remove high-frequency noise.
Procedure
On arrival, participants were seated in a recliner in
a3m×1.5mcubicle. Then, the following cover story
based on that used by Strack et al. (1988) was given:
This research is part of a project on physically handi-
capped persons who are unable to use their hands to
exercise control over their environment. However, one
may expect that training would make these persons able
to use other parts of their body (mouth, feet) in order to
do daily routine psychomotor or cognitive tasks (e.g., to
use a pen/pencil to complete a questionnaire, to direct a
remote control in order to run a television, to use a
telephone). It is obvious that their ability to exercise
control over their milieu with different parts of their
body may contribute to improve the quality of their fu-
ture life. What we would like to know is whether the
manipulation of objects (e.g., pencil, remote control) by
other parts of the body (e.g., the mouth) may affect the
attentional abilities and the responsiveness of these per-
sons because of the potentially negative side effects of
this task (e.g., due to difficulty and unpleasantness). Be-
fore conducting such a study in physically impaired
people it is important to collect data in non-handicapped
persons, not only to perfect the procedure but also to
provide information on the performances and reactions
of a control group. The tasks we would like you to
perform aim specifically (a) at assessing your reactions
to a particular pencil-holding technique with the mouth
(i.e., difficulty and pleasantness of the task), (b) at ex-
amining the effect of this technique on both your psy-
chomotor performance (to underline some targets), and
attention to videotaped scenes broadcast on a television
screen. A pencil will be used because it is a usual daily
object and it can also simulate a remote control (e.g., to
run a television). Several techniques of pencil holding
will be compared (pencil held with the teeth or with the
lips) because an important aim of this research is to
select the most adequate and the least cumbersome. We
will compare data of four experimental groups (i.e., four
techniques of pencil holding), but each participant will
be only assigned to one technique. To ensure you have
carefully followed experimenter’s instructions, the pro-
cedure will be videotaped. We are asking you to do two
tasks. The first task consists in holding a pencil with the
mouth (one of the four techniques), to direct it towards
some specific targets on a sheet (i.e., vowels), and to
underline them quickly when the experimenter will sig-
nal you (psychomotor task). In the second task, you will
also have to hold the pencil with the mouth, and to direct
it towards the television facing you by focusing your
attention on the video records that last 10 s (attention
task). The pencil will simulate a remote control. Several
variables will be measured to check whether the object
holding affects both your perception, attention, and in-
duces unpleasantness: self-report items of a question-
naire and psychophysiological parameters.
Each participant signed a consent form indicating
her acceptance of the procedure and her permission
for further use of video records. For each task an
experimenter demonstrated the correct way to hold
the pencil.
1
Then, after putting another new pencil to
1
Each pencil-holding condition was demonstrated twice
by a certified Facial Action Coding System (FACS; Ekman
DUCHENNE SMILE AND EMOTIONAL EXPERIENCE
57
participants’ lips, the experimenter asked them to re-
produce the action. A lightweight pencil was chosen
to reduce muscular effort required to hold the object
(diameter: 7 mm, length: 17 cm, weight: 10 g). The
four following experimental conditions were defined
(see Figure 1 for examples):
In the first condition (the control group; CG), par-
ticipants were instructed to hold the pencil between
the teeth. It was emphasized that they should open
slightly their lips without touching the object (i.e.,
maintaining 3 or 4 mm between the lips and the pen-
cil). This task involved the lowering of the mandible
(producing action unit [AU] 26, or jaw dropping in
the Facial Action Coding System [FACS; Ekman &
Friesen, 1978] terminology)
2
produced by the relax-
ation of temporal and internal pterygoid muscles. In
the second condition (the lips pressing group; LPG),
participants were instructed to tightly hold the pencil
with the lips without touching it with their teeth. This
AU involved the muscular contraction of the orbicu-
laris oris muscle that produces the pressing of lips
(AU 24, or lips pressing in the FACS terminology).
In the third and fourth conditions, participants were
instructed to avoid any contact of the lips with the
pencil by holding it with their front teeth and by
reproducing the level of action produced by the ex-
perimenter during the task. Participants were told that
this condition was included because objects of distinct
size might be manipulated during everyday life. Thus,
they thought that distinct levels of teeth conditions
were required to take into account the diversity of
daily situations. The third condition (the non-
Duchenne smile group; n-DSG) involved both the
& Friesen, 1978) coder (Robert Soussignan). The first time,
the experimenter showed the correct way to hold the pencil
during about 5 s. After the participants had performed the
requested task, the experimenter showed the correct tech-
nique a second time during the same duration, and again he
instructed the participants to perform the task.
2
The FACS is a comprehensive anatomically based tech-
nique developed by Ekman and Friesen (1978) for measur-
ing all minimally observable facial changes that muscles
can produce (action units; AU). Each AU is designated by
a numeric code and scored on the basis of precise transitory
changes in the shape and location of the facial features such
as wrinkles, bulges, or pouches of the skin. FACS intensity
ratings range from A (very slight intensity)toE(strongest
possible intensity).
Figure 1. Illustration of the technique used to induce distinct facial configurations: (a) jaw dropping (control group), (b) lips
pressing (lips pressing group), (c) lips corner pulling (non-Duchenne smile group), and (d) lips corner pulling and cheeks
raising (Duchenne smile group).
SOUSSIGNAN
58
contraction of zygomaticus major muscles at a C level
(producing AU 12, or lips corner pulling in the FACS
terminology) and the relaxation of temporal and in-
ternal pterygoid muscles, whereas in the fourth con-
dition (the Duchenne smile group; DSG) the contrac-
tion of zygomaticus major muscles was performed at
a D level, in conjunction with orbicularis oculi
muscles
3
(producing AU 6, or cheek raising in the
FACS terminology). Thus, no instructions were given
to direct the participants’ attention on smiling patterns
or on the muscles responsible for zygomatic and or-
bicularis oculi actions. In addition, participants were
not asked to voluntarily produce AU 6, nor were they
submitted to systematic trials and training to correct
the expressions. Only distinct levels of pencil avoid-
ance with the lips were required. It was expected that
both this instruction and the reproduction of the hold-
ing technique shown by the model would have in-
creased the probability that the participants displayed
Duchenne smiles.
Following the instruction phase, physiological sen-
sors were attached, and participants were asked to re-
main quiet throughout the experiment. Then, they per-
formed the two tasks. In the psychomotor task, they
were shown 11 consonants and 2 vowels printed ran-
domly on a sheet of paper. Then, after the pencil was put
into their mouth (teeth or lips conditions), they were told
to underline only the vowels as quickly as they could at
a signal given by the experimenter. After doing so, the
performance time was noted, and they were instructed to
verbally report the degree of task difficulty on a 10-point
scale (0 not at all difficult to 9 very difficult) and
the degree of pleasantness of the pencil-holding tech-
nique on a scale ranging from –9 (very unpleasant)to9
(very pleasant). In the attention task, the participants
were told that they would be shown several short films
and they should use the same technique of pencil hold-
ing by directing their attention on videotapes. They were
told that videoclips were selected to be more or less
pleasant and more or less funny. The video records were
shown on a 72-cm television screen placed at a distance
of 2.5 m from the participants face. The presentation of
the positive and negative video records was randomized
in a single order. Following a 90-s rest period, the pencil
was put into their mouth by the experimenter, and the
videotaped sequence was projected. During the projec-
tion, the experimenter stayed behind the participants and
did not look at the videoclips. At the end of each se-
quence the pencil was taken and put on a paper tissue.
After viewing each video record, the participants were
asked, “How did you react to the videoclip?” The re-
sponse scale to the scene ranged from −9 (very nega-
tively)to9(very positively). They were also instructed to
report (a) the degree of pleasantness of the pencil-
holding procedure on a scale ranging from −9 (very
unpleasant)to9(very pleasant) and (b) the degree of
difficulty of the pencil-holding technique on a 10-point
scale ranging from 0 (no difficulty)to9(very difficult).
Participants’ attention was then evaluated by asking
them a question about the scene content.
Finally, the participants were instructed to hold the
pencil with their teeth or lips, corresponding to the re-
spective condition, for 10 s while the emotional stimuli
were not projected. Although they were told that this
recording aimed to investigate the specific effect of pen-
cil-holding techniques on physiological parameters, this
test was included to examine whether changes of auto-
nomic response patterns (heart rate, respiration, skin
conductance, temperature) were not directly the conse-
quence of differences in muscular effort-related changes
between the pencil-holding techniques regardless of the
projection of video scenes.
Debriefing About the Purposes of
the Experiment
At the end of the experiment, the participants were
instructed to identify and describe the purposes of the
3
In a moderate smiling (i.e., B or C level) the minimum
criteria for scoring AU 12 are the following (Ekman &
Friesen, 1978): (a) Skin in the areas of the lower-middle
portion of the nasolabial furrow or the furrow itself has been
raised up and is slightly lateral, (b) slight evidence that
infraorbital triangle has been raised, and (c) slight evidence
that lip corners are elongated and angled up. A strong smil-
ing (i.e.,aDorElevel recruiting AU 6) produced additional
changes: (a) presence of crow’s-feet wrinkles, (b) marked
narrowing of the eyes opening, and (c) slight infraorbital
triangle raise. In a strong smiling without AU 6, the appear-
ance changes due to AU 12 are more pronounced (i.e., the
infraorbital triangle upward push is more evident, the infra-
orbital furrow deepening is more evident). It can be noted
that a Duchenne smile withaBorClevel is uncommon, and
when smiling reachesaDorElevel, Duchenne smiling is
often produced (Ekman & Friesen, 1978). So, it was ex-
pected that reproducing a pencil-holding task with intense
lip movement would induce cheeks raising with furrows in
the eye region (because of the contraction of orbicularis
oculi muscles). However, it can be noted that our instruc-
tions did not always induce Duchenne smiles despite the
fact that participants indeed produced a D-level zygomatic
action in the teeth condition. This explains why about 30%
of participants of this group were later excluded from the
analysis.
DUCHENNE SMILE AND EMOTIONAL EXPERIENCE
59
study on a paper sheet. They were also asked to report
purposes that were not given in the instruction proce-
dure. None of participants suspected the true nature of
experimental hypotheses. Most of them reported that
the goals were to devise an appropriate object-holding
procedure and to test its interference with daily tasks
in order to make the life easier for motor handicapped
persons. Thus, it can be concluded that the cover story
was really effective.
Facial Control and Data Reduction
The recording of each participant’s face was later
inspected by a certified coder who had previously
taken a FACS final proficiency test. This coding sys-
tem was used during the previous 10-s baseline period
and the 10-s pencil-holding period to verify that the
facial displays (a) did not contain extraneous muscle
movements (e.g., brow lowering, upper-lip raising)
and (b) were consistent with the instructions regarding
the required actions.
Among the participants, 28 failed to exhibit the
strictly required patterns of facial actions. In this sub-
sample, a number of participants expressed additional
AUs, besides the requested facial patterns, while they
were presented with the stimulus (n 21). They were
thus excluded from the analysis.
4
A second subsample
(n 7), drawn from the DSG, failed to display AU 6
(cheek raising) despite the fact that they produced the
same zygomatic intensity (i.e., D-level intensity).
Consequently, two comparisons were made. First, the
analysis testing the monotonicity hypothesis com-
pared data of the following groups: CG (n 15),
LPG (n 18), C-level n-DSG (n 18), and DSG (n
17). Second, we explored the role of the morphol-
ogy of smiling (due to orbicularis oculi activity) by
comparing the DSG to the subsample of n-DSG show-
ing the same zygomatic intensity (i.e., D-level n-
DSG).
Second-by-second values for each autonomic mea-
sure were averaged for each of the two epochs: the
10-s prestimulus period and the 10-s stimulus period.
Dependent variables were computed off-line from
these measures by subtracting for each trial the mean
of psychophysiological data (i.e., heart rate, respira-
tory rate, skin conductance, bodily temperature) dur-
ing the prestimulus level (i.e., 10 s prior to each
stimulus presentation) from the mean of the psycho-
physiological data during the 10 s of stimulus presen-
tation.
Statistical Analyses
Emotional ratings and autonomic measures were
analyzed using4×2×2×2(Facial Configuration ×
Valence × Intensity × Stimulus) repeated-measures
analyses of covariance (ANCOVAs), with Facial
Configuration as a between-subjects factor and the
other variables as within-subjects factors. Mean rat-
ings of task difficulty and task pleasantness were en-
tered as covariates. Fisher’s least significant differ-
ence test (LSD; Winer, 1971) was used for making
post hoc multiple comparisons between means. The
strength of experimental effects and the effect sizes
were also reported using respectively eta-squared
(
2
), and
2
/1-
2
as measures (Cohen, 1988;
Howel, 1992). Cohen (1988) has defined a small ef-
fect as 0.10, a medium effect as 0.25, and
a large effect as 0.40.
Results
Facial Configurations Comparisons
Self-reported emotional reaction. The ANCOVA
yielded no significant effects for the ratings of task
pleasantness, F(1, 62) 0.47, ns, and task difficulty,
F(1, 62) 0.21, ns, as covariates. As expected, there
was a significant main effect of Valence, F(1, 62)
209.11, p < .0001 (
2
0.771, effect size 1.83),
and significant Valence × Intensity, F(1, 62) 45.54,
p < .0001 (
2
0.423, effect size 0.86), and
Valence × Stimulus interactions, F(1, 62) 13.98, p
< .0001 (
2
0.184, effect size 0.47), on the
self-reported emotional response to the videoclips.
Post hoc comparisons revealed that participants re-
sponded with more strongly positive reactions to car-
toons (M 6.49, SE 0.22) than they did to pleas-
ant videoclips (M 5.23, SE 0.26, for landscape
and chimpanzee stimuli), p .001. The strongly un-
pleasant scenes induced more negative emotional re-
actions (M −5.72, SE 0.26, for videoclips of
mutilation and stretched animal) than did the mildly
unpleasant scenes (M −2.60, SE 0.33, for vid-
eoclips of the bat and ants), p < .0001.
In sum, although participants of the main experi-
ment tended to report less negative emotional experi-
ence to unpleasant scenes than to those of the stimulus
selection procedure, a clear differentiation was found
4
The following AUs were displayed during the presen-
tation of the video records: AU 4 (brow lowering), AU 1 +
4/1+2+4(brow raising and lowering), AU 10 (upper-lip
raising), AU 17 (chin raising), and AU 20 (lip stretching).
These facial actions were shown to be signs of various
negative affects (e.g., Ekman et al., 1980). Therefore, the
participants displaying negative AUs were excluded.
SOUSSIGNAN
60
between videoclips that were mildly and strongly
evocative of positive or negative affect.
More interesting, the main effect for Facial Con-
figuration was significant, F(3, 62) 4.33, p .008
(
2
0.173, effect size 0.46). Post hoc pairwise
comparisons showed that the DSG, on average, re-
acted more positively to the videoclips compared with
other groups of participants: DSG vs. CG: p < .01;
DSG vs. LPG: p < .01; DSG vs. n-DSG: p < .05 (see
Figure 2).
The Facial Configuration × Valence interaction was
not significant, F(3, 62) 1.32, p .27. However,
the Facial Configuration × Valence × Intensity inter-
action approached significance, F(3, 62) 2.30, p
.08 (
2
0.1, effect size 0.33). Follow-up uni-
variate ANCOVAs revealed main effects of Facial
Configuration for positive videoclips (all ps < .05),
whereas no significant differences emerged between
the four facial configuration groups when unpleasant
scenes were presented (p > .05).
Adjusted means and statistics are summarized in
Table 1. As can be seen, only the DSG reported higher
positive emotional experience during mildly and
strongly intense conditions. More specifically, LSD
tests revealed that the DSG reported more positive
emotional ratings than did the CG (except for the
landscape stimulus) and the LPG. The DSG reacted
also more positively than did the n-DSG to the pleas-
ant stimulus (landscape and chimpanzee, p < .05), and
Cartoon 1 (p < .05), whereas the difference of emo-
tional scores approached significance for the other
positive stimulus (Cartoon 2, p 0.1).
Inspection of effect sizes for the reported signifi-
cant effects (Valence, Valence × Intensity, Valence ×
Stimulus, Facial Configuration) revealed that they are
similar or higher than 0.4. Thus, it can be suggested
that the magnitude of experimental effects is large
(Cohen, 1988).
Skin conductance. Data from two participants of
the DSG were excluded because of recording arti-
facts. The ANCOVA performed on the skin conduc-
tance changes yielded no significant effects for the
ratings of task difficulty and task pleasantness as co-
variates, all ps > .50. The Facial Configuration effect
approached significance, F(3, 60) 2.65, p .057
(
2
0.117, effect size 0.36). Post hoc LSD tests
indicated that the magnitude of skin conductance
changes was higher for DSG as compared with other
groups of participants (CG: p .008; LPG: p .06;
n-DSG: p .03). No other main effects were signifi-
cant. However, the Facial Configuration × Stimulus
interaction was significant, F(3, 60) 3.72, p < .05
(
2
0.157, effect size 0.43), as was the Facial
Configuration × Valence × Stimulus interaction, F(3,
60) 3.83, p < .05 (
2
0.161, effect size 0.44).
One-way ANCOVAs followed by Fisher’s LSD tests
revealed that these interactions reflect the fact that the
DSG showed greater increases in skin conductance
while exposed to one of the positive videoclips (i.e.,
Cartoon 1), F(3, 60) 4.61, p < .01 (
2
0.187,
effect size 0.48), as compared with the participants
of other groups, all ps < .05 (see Table 2).
Heart rate. The data from one participant of the
LPG were unavailable because of equipment prob-
lems. The repeated-measures ANCOVA on heart rate
changes did not show any significant effect for the
ratings of task pleasantness and task difficulty as co-
variates, all ps > 0.1. The analysis revealed no heart-
rate differences as a function of the type of Facial
Configuration, F(3, 61) 1.76, p .165. There
were also no significant main effects involving Va-
lence, Intensity, and Stimulus (all ps > .05). However,
significant Facial Configuration × Valence × Intensity
interaction, F(3, 61) 2.85, p < .05 (
2
0.123,
effect size 0.37), as well as Facial Configuration ×
Valence × Stimulus interaction, F(3, 61) 2.76, p
.05 (
2
0.119, effect size 0.37) were detected.
One-way ANCOVAs followed by Fisher’s LSD pro-
cedure were run to elucidate the meanings of these
triple interactions. As illustrated in Table 3, compared
with other groups, the DSG showed a higher heart rate
change while viewing one of the strongly positive
videoclips (i.e., Cartoon 1), F(3, 61) 2.97, p < .05,
2
0.128, effect size 0.38, (DSG vs. CG: p <
.05; DSG vs. LPG: p < .01; DSG vs. n-DSG: p
.06). Inspection of Table 3 indicates also that both CG
and LPG evinced decreases for almost all the video-
clips, whereas the DSG showed increased heart rate
Figure 2. Self-reports of emotional reaction as a function
of the type of facial configuration while participants were
shown videoclips. CG control group; LPG lips press-
ing group; n-DSG non-Duchenne smile group; DSG
Duchenne smile group.
DUCHENNE SMILE AND EMOTIONAL EXPERIENCE
61
Table 1
Adjusted Mean, Standard Error, and Effect Size for Self-Report of Emotional Experience During the Four Facial Configurations as a Function of Affective Valence
and Intensity Dimension of Videoclips
Condition
Positive Negative
Mildly Strongly Mildly Strongly
Landscape Chimpanzee Cartoon 1 Cartoon 2 Bat Ants Stretched animal Mutilation
M SE M SE M SE M SE M SE M SE M SE M SE
CG (n 15) 4.66 0.76 5.03
a
0.55 5.32
a
0.55 6.00
a
0.52 −1.78 0.98 −4.62 1.03 −5.35 0.68 −5.45 0.77
LPG (n 18) 3.46
a
0.67 5.11
a
0.49 5.94
a
0.49 5.98
a
0.46 −1.31 0.87 −3.47 0.91 −5.34 0.60 −6.27 0.68
n-DSG (n 18) 4.16
a
0.67 5.93
a
0.39 6.29
a
0.48 6.87 0.46 −1.40 0.86 −3.30 0.91 −6.60 0.60 −6.26 0.68
DSG (n 17) 6.18 0.69 7.34 0.50 7.65 0.50 7.86 0.47 −1.49 0.89 −3.40 0.94 −4.80 0.62 −5.68 0.70
F 2.89* 4.60** 3.66* 3.42* 0.45 0.36 1.57 0.33
2
0.123 0.182 0.151 0.142 0.002 0.017 0.071 0.016
effect size 0.37 0.47 0.42 0.41 0.04 0.13 0.28 0.13
Note. Asterisks indicate that univariate analyses of covariance revealed significant differences between the four conditions of facial configuration (df 3, 62).
CG control group; LPG lips pressing group; n-DSG non-Duchenne smile group; DSG Duchenne smile group.
a
Mean differences between the DSG and other groups are significant at p < .05.
* p < .05. **p < .01.
SOUSSIGNAN62
Table 2
Adjusted Mean Change From Prevideoclip Period and Standard Error for Skin Conductance Level During the Four Facial Configurations as a Function of Affective
Valence and Intensity Dimension of Videoclips
Condition
Positive Negative
Mildly Strongly Mildly Strongly
Landscape Chimpanzee Cartoon 1 Cartoon 2 Bat Ants Stretched animal Mutilation
M SE M SE M SE M SE M SE M SE M SE M SE
CG (n 15) 0.53 0.25 0.30 0.26 0.15 0.24 0.40 0.21 0.27 0.25 0.20 0.20 0.21 0.19 0.21 0.10
LPG (n 18) 0.90 0.23 0.75 0.23 0.11 0.22 0.48 0.19 0.52 0.23 0.36 0.19 0.42 0.17 0.19 0.21
n-DSG (n 18) 0.74 0.23 0.79 0.23 0.14 0.22 0.23 0.19 0.39 0.22 0.38 0.19 0.27 0.17 0.30 0.21
DSG (n 15) 1.43 0.26 0.89 0.26 1.19
a
0.24 0.03 0.21 0.77 0.25 0.49 0.20 0.75 0.19 0.88 0.23
Note. CG control group; LPG lips pressing group; n-DSG non-Duchenne smile group; DSG Duchenne smile group.
a
Mean differences between the DSG and other groups are significant at p < .05.
DUCHENNE SMILE AND EMOTIONAL EXPERIENCE 63
Table 3
Adjusted Mean Change From Prevideoclip Period and Standard Error for Heart Rate During the Four Facial Configurations as a Function of Affective Valence and
Intensity Dimension of Videoclips
Condition
Positive Negative
Mildly Strongly Mildly Strongly
Landscape Chimpanzee Cartoon 1 Cartoon 2 Bat Ants Stretched animal Mutilation
M SE M SE M SE M SE M SE M SE M SE M SE
CG (n 15) −0.25 1.71 −0.22 1.21 −1.06 1.11 −0.96 0.98 −2.69 1.44 −2.53 1.25 −0.19 1.40 0.09 1.13
LPG (n 17) −2.99 1.56 −0.34 1.11 −1.37 1.02 −0.98 0.90 −0.85 1.31 −0.002 1.14 −1.69 1.28 −3.44
a
1.03
n-DSG (n 18) 0.42 1.50 0.06 1.06 −0.20 0.98 1.33 0.86 1.44 1.27 −0.55 1.10 −0.05 1.23 −0.24 0.99
DSG (n 17) −1.54 1.55 2.56 1.10 2.49
a
1.00 1.26 0.89 0.19 1.30 0.71 1.13 −0.66 1.27 0.23 1.03
Note. CG control group; LPG lips pressing group; n-DSG non-Duchenne smile group; DSG Duchenne smile group.
a
Mean differences between the groups are significant at p < .05.
SOUSSIGNAN64
for three positive videoclips. In addition, compared
with other groups, the LPG showed a higher decrease
of heart rate while viewing one of the most unpleasant
videoclips, F(3, 61) 2.79, p < .05, (
2
0.121,
effect size 0.37).
Respiratory rate. Using respiratory rate as the de-
pendent variable, the 4 (Facial Configuration) × 2
(Valence) × 2 (Intensity) × 2 (Stimulus) repeated-
measures ANCOVA yielded no significant effects for
any of the main independent variables or for the in-
teraction between these variables (p > .05).
Bodily temperature. The four-factor ANCOVA
(Facial Configuration × Valence × Intensity × Stimu-
lus) also yielded no significant effects for the main
independent variables or for the interaction between
these variables (p > .05).
Form of Smiling
When smiles with the Duchenne marker are spon-
taneously displayed during solitary and social inter-
action situations, they are characterized by greater zy-
gomatic intensity than are smiles without the
Duchenne marker (Frank et al., 1993). Thus, Du-
chenne smiles may be differentiated from non-
Duchenne smiles in both morphology (presence of
orbicularis oculi action) and intensity. In our study,
the induction of Duchenne smiles was based on a
procedure that generated zygomatic actions of greater
intensity than those of non-Duchenne smiles. Thus,
the above findings may result not solely from the
additional recruitment of the orbicularis oculi action
but also from the greater intensity of zygomatic major
action. Although, our main purpose was not to disen-
tangle the relative contribution of these two behavior-
al markers in the facial modulation of experiential and
physiological measures, we compared the findings of
the DSG with data collected in a subsample of par-
ticipants (n 7), who initially belonged to the DSG
but who were excluded because their facial pattern did
not recruit the Duchenne marker, despite the fact that
they showed evidence of a zygomatic major action at
D level
5
(i.e., D-level n-DSG). The C-level n-DSG
was also included into the analysis as a control group.
A four-way ANCOVA (Form of Smiling × Valence
× Intensity × Stimulus), with Form of Smiling (DSG,
D-level n-DSG, C-level n-DSG) as the between-
subjects factor and the other variables as within-
subjects factors, was carried out on subjective emo-
tional reactions to videoclips. The ratings of task
pleasantness and task difficulty were entered as co-
variates. The analysis yielded no significant effect for
task pleasantness and task difficulty as covariates, all
ps > .25. As we expected, significant effects were
detected for Valence, F(1, 37) 128.09, p < .0001
(
2
0.776, effect size 1.86); Intensity, F(1, 37)
4.23, p < .05 (
2
0.103, effect size 0.34);
Valence × Intensity interaction, F(1, 37) 46.10, p <
.001 (
2
0.55, effect size 1.10); and Valence ×
Stimulus interaction, F(1, 37) 4.92, p < .05 (
2
0.117, effect size 0.36). There was also a signifi-
cant main effect for Form of Smiling, F(2, 37)
5.02, p < .05 (
2
0.213, effect size 0.52). Fol-
low-up univariate ANCOVAs followed by Fisher’s
LSD tests revealed that the DSG reported greater
positive reaction than did the D-level n-DSG while
viewing pleasant and funny videoclips (landscape: p <
.05, chimpanzee: p < .01, Cartoon 1: p < .05), whereas
no significant difference was detected between the
two non-Duchenne conditions (see Table 4). Inspec-
tion of effect sizes for the significant findings indi-
cated that they are higher than 0.4. Thus, it can be
suggested that the effects are large.
Four-way ANCOVAs (Form of Smiling × Valence
× Intensity × Stimulus) were also conducted on each
autonomic measure, with Form of Smiling as the be-
tween-subjects factor and the other variables as
within-subjects factors. The pleasantness ratings and
the difficulty ratings of the task were entered as co-
variates.
For skin conductance, no significant main effects
were detected. However, there were significant inter-
actions between Form of Smiling and Stimulus, F(2,
35) 6.53, p < .01 (
2
0.272, effect size 0.61),
as well as between Form of Smiling, Valence, and
Stimulus, F(2, 35) 7.05, p < .01 (
2
0.287,
effect size 0.63). Follow-up one-way ANCOVAs
followed by LSD tests indicated that the DSG exhib-
ited higher increases in skin conductance than did the
D-level n-DSG only for the landscape videoclip (M
1.43 vs. 0.29), F(2, 35) 4.08, p < .05 (
2
0.215,
effect size 0.52).
For heart rate, there also was a Form of Smiling ×
Valence × Stimulus interaction, F(2, 37) 3.73, p <
.05 (
2
0.168, effect size 0.45). The other ef-
5
Given that the criterion of differentiation between the
Duchenne and the non-Duchenne smile groups was origi-
nally based on the degree of avoidance of the pencil, inten-
sity and presence of orbicularis oculi action were obviously
confounded. However, as it can be remembered, this choice
was dictated by the necessity to recruit the orbicularis oculi
action without asking participants to contract the muscle
responsible of this action to rule out situational demands.
DUCHENNE SMILE AND EMOTIONAL EXPERIENCE
65
Table 4
Adjusted Mean, Standard Error, and Effect Size for Self-Report of Emotional Experience During Videoclips as a Function of the Form of Smiling
Condition
Positive Negative
Mildly Strongly Mildly Strongly
Landscape Chimpanzee Cartoon 1 Cartoon 2 Bat Ants Stretched animal Mutilation
M SE M SE M SE M SE M SE M SE M SE M SE
C-level n-DSG (n 18) 4.24
a
0.62 5.95
a
0.46 6.27
a
0.40 6.88 0.37 −1.42 0.94 −3.35 0.89 −6.67 0.60 −6.23 0.67
D-level n-DSG (n 7) 3.61
a
1.00 4.94
a
0.74 6.28
a
0.64 6.79 0.60 −1.36 1.51 −2.28 1.43 −4.71 0.97 −4.93 1.08
DSG (n 17) 6.26 0.64 7.37 0.47 7.65 0.41 7.86 0.39 −1.52 0.96 −3.45 0.92 −4.88 0.62 −5.67 0.69
F 3.66* 4.72* 3.39* 2.04 0.005 0.26 2.66 0.55
2
0.165 0.203 0.155 0.099 0.0 0.01 0.126 0.029
Effect size 0.44 0.50 0.43 0.33 0.0 0.10 0.38 0.17
Note. C-level n-DSG C-level non-Duchenne smile group; D-level n-DSG D-level non-Duchenne smile group; DSG Duchenne smile group. Asterisks indicate that univariate analyses
of covariance revealed significant differences between the four conditions of facial configuration (df 2, 37).
a
Mean differences between the DSG and other groups are significant at p < .05.
* p < .05.
SOUSSIGNAN66
fects were not significant. Post hoc comparisons in-
dicated that this interaction reflects the fact that the
DSG globally reacted more to some positive video-
clips (i.e., chimpanzee and Cartoon 1: M 2.57, SE
1.08) than to others (landscape and Cartoon 2: M
−0.16, SE 1.06), as compared with the n-DSG
groups, p < .05.
Finally, for respiratory rate and bodily temperature,
there were no other significant main or interaction
effects.
Pleasantness and Difficulty Ratings of the
Pencil-Holding Tasks
Although the ANCOVAs revealed that the findings
were not produced by differences in the degree of
pleasantness and difficulty of the four experimental
conditions, additional analyses were performed to
verify whether participants differentially reacted to
the distinct pencil-holding tasks. A 5 (Facial Configu-
ration) × 2 (Valence) × 2 (Intensity) × 2 (Stimulus)
repeated-measures ANOVA was conducted on the
pleasantness scores. There were no significant main
effects associated with any of these variables. Com-
parison of means of the five groups of participants
performing the distinct pencil-holding techniques in-
dicated that they self-reported similar ratings of slight
unpleasantness, F(4, 70) .10, p .98 (CG: M
−1.36, SE 0.72; LPG: M −0.95, SE 0.65;
C-level n-DSG: M −1.33, SE 0.65; D-level n-
DSG: M −1.68, SE 1.05; DSG: M −1.23, SE
0.67). Significant differences were only found for
two- and three-way interactions between Valence, In-
tensity, and Stimulus. For the Valence × Intensity
interaction: F(1, 70) 7.00, p < .05,
2
0.092,
effect size 0.32; Intensity × Stimulus interaction:
F(1, 70) 6.39, p < .05,
2
0.084, effect size
0.30; Valence × Intensity × Stimulus interaction: F(1,
70) 4.08, p < .05,
2
0.064, effect size 0.26.
These significant interactions were especially attrib-
utable to the fact that the pencil-holding techniques
induced lower unpleasant scores during the presenta-
tion of cartoons (Cartoon 1: M −0.68, SE 0.36;
Cartoon 2: M −1,04, SE 0.40) than they did
during the presentation of highly negative scenes
(stretched animal: M −1.55, SE 0.39, mutilation:
M −1.71, SE 0.41, matched t tests, all ps < .05).
A second possible confounding variable that may
explain part of our findings concerns the different
degrees of difficulty for the four pencil-holding tech-
niques. Examining the 5 (Facial Configuration) × 2
(Valence) × 2 (Intensity) × 2 (Stimulus) ANOVA on
difficulty ratings, we detected no main effects for any
of the four independent variables. Although the CG
rated the pencil-holding task as less difficult com-
pared with other facial configuration groups, the di-
rection of the finding was contrary to the hypothesis
and the difference failed to reach significance (CG: M
1.83, SE 0.49; LPG: M 3.29, SE 0.45;
C-level n-DSG: M 3.14, SE 0.45; D-level n-
DSG: M 3.45, SE 0.72; DSG: M 3.12, SE
0.46), F(4, 70) 1.64, p .174. The interactions
between the different independent variables were also
not significant.
Pearson product–moment correlation coefficients
were also computed for each stimulus condition
across all participants. The analysis revealed that rat-
ings of task difficulty were negatively correlated with
ratings of task pleasantness for five of the stimulus
conditions, r (73) ranged from −0.30 to −0.41, p < .05.
Finally, no significant correlations were apparent be-
tween emotional ratings and difficulty ratings, on the
one hand, and emotional ratings and unpleasantness
ratings, on the other hand (p > .05).
Relationship Between Self-Reported Emotion
and Physiological Measures
Correlations among subjective emotional reactions
and physiological measures were computed for each
stimulus condition across all participants. No clearly
interpretable patterns emerged given the analyses re-
vealed only a small number of significant correlations
between subjective reports of affective experience and
autonomic measures (i.e., Cartoon 1: r(73) 0.28, p
< .05, for skin conductance; Cartoon 2: r(74) 0.28,
p < .05, for heart rate).
Autonomic Activity During the
Pencil-Holding Procedure
To investigate whether the muscular effort pro-
duced during the pencil-holding techniques influences
autonomic nervous system activity, means of physi-
ological measures 10 s before the task were subtracted
from the average physiological measures collected
during the 10 s period of the pencil-holding task. Data
were analyzed using one-way ANOVAs on each
physiological measure with Facial Configuration
(CG, LPG, C-level n-DSG, D-level n-DSG, DSG) as
the between-subjects factor. Statistical analyses
yielded no significant differences between the five
groups for the four autonomic measures: skin conduc-
tance: F(4, 68) 1.30, p 0.28; heart rate: F(4, 69)
1.67, p 0.168; respiratory rate: F(4, 70) 1.62,
p 0.179; bodily temperature: F(4, 70) 0.554, p
0.704. Mean values of autonomic parameters for
DUCHENNE SMILE AND EMOTIONAL EXPERIENCE 67
the five facial configurations are shown in Table 5. As
can be seen, the pattern of activity varied as a function
of the physiological measure: Heart rate and bodily
temperature tended to decrease, whereas skin conduc-
tance and respiratory rate tended to increase during
the production of the pencil-holding procedure. These
findings suggest that muscular effort-related changes
alone do not explain the differential pattern of auto-
nomic responsiveness shown in the participants who
displayed the Duchenne smile during the presentation
of the emotional video sequences.
Discussion
This research addressed four issues derived from
the facial feedback hypothesis with a methodology
based on Strack et al.’s (1988) procedure (i.e., oral
pencil-holding technique). The first aim was to repli-
cate and extend their work by examining more strin-
gently the facilitating influence of zygomatic action
on self-reported emotional experience and autonomic
nervous system activity. Because of a variety of limi-
tations in their study, the present experiment included
a number of methodological issues (e.g., selection of
faces with the requested actions, use of a control face
without emotional actions, control of intensity and
duration of movement, partialling out of task unpleas-
antness). Our findings confirm the heuristic value of
Strack et al.’s procedure in supporting the view that
the unconscious facilitation of one form of human
smile reliably affects the rating of emotional experi-
ence. Specifically, production of Duchenne smiles,
which involves the joint actions of the zygomatic ma-
jor and orbicularis oculi, increased self-report of posi-
tive experience in participants exposed to videoclips
of pleasant stimuli and funny cartoons. However, con-
trarily to Strack et al.’s research, the present study
failed to demonstrate that the contraction of zygomati-
cus muscles alone was sufficient to induce reliable
subjective or autonomic changes. There are two pos-
sible explanations for these conflicting results. On the
one hand, methodological shortcomings due to pos-
sible variations across and within their experimental
conditions (e.g., difference of unpleasantness between
their two pen-holding tasks, lack of an adequate facial
control, presence of additional facial actions, intensity
change of zygomatic action) may have contaminated
part of their findings. For instance, one may wonder
whether funny cartoons used in their study did not
change the intensity and the form of smiling in a
number of participants (e.g., recruitment of orbicu-
laris oculi action), thus explaining the observed ef-
fects. On the other hand, procedural differences
among the studies also may be proposed as an alter-
native explanation for our failure to find a facilitating
effect of non-Duchenne smiles on positive emotional
experience. Differences in duration of feedback ef-
fects (i.e., duration of lips contraction), self-report
scales (self-reported positive reactions vs. funniness
ratings), and stimulus material (i.e., videoclips of
pleasant scenes and funny cartoons vs. magazines of
funny cartoons) may have contributed to the discrep-
ancy. Because our rating scale confounded positive
responses to both pleasant and humorous stimuli, the
hypothesis that non-Duchenne smiles could have a
feedback effect only when people rated funniness of
cartoons cannot be completely ruled out. In addition,
it is possible that different participants who were
asked to report their affective reaction may have con-
strued the meaning of reacting in different ways (e.g.,
an affective reaction in terms of feeling vs. a cogni-
tive–moral reaction toward what is shown in the clip).
It is interesting that a feedback effect of non-
Duchenne smiles was reported in Strack et al.’s re-
search (Study 2) when participants were given the
opportunity to differentiate between a cognitive com-
ponent (i.e., perceived funniness content of cartoons)
Table 5
Mean Change in Autonomic Measures and Standard Error of the Mean as a Function of the Pencil-Holding Tasks
Condition
SC HR RR BT
M SE M SE M SE M SE
CG (n 15) 0.14 0.13 −3.90 1.10 0.11 1.43 −0.010 0.02
LPG (n 18) 0.06 0.12 −4.13 1.03 3.01 1.30 −0.050 0.02
C-level n-DSG (n 18) 0.28 0.12 −1.64 1.00 −1.11 1.30 −0.020 0.02
D-level n-DSG (n 7) 0.37 0.18 −0.14 1.62 2.34 2.13 −0.001 0.02
DSG (n 17) 0.39 0.13 −3.10 1.03 2.42 1.34 −0.040 0.02
Note. SC skin conductance; HR heart rate; RR respiratory rate; BT bodily temperature; CG control group; LPG lips
pressing group; C-level n-DSG C-level non-Duchenne smile group; D-level n-DSG D-level non-Duchenne smile group; DSG
Duchenne smile group.
SOUSSIGNAN68
and an affective component (i.e., subjective feeling of
amusement) of the humor response (Gavanski, 1986;
Leventhal & Mace, 1970). The smiling behavior had
an effect on humor reactions only when participants
were asked to report their feeling of amusement.
Further research is needed to substantiate whether
this lack of replication of Strack et al.’s (1988) find-
ings is strictly dependent on methodological limita-
tions rather than on procedural differences between
the studies. In particular, it will be important to ex-
amine whether non-Duchenne smiles alone have a
differential feedback effect on pleasantness and
amusement ratings while controlling a number of po-
tential methodological artifacts.
The second issue addressed by the present study
was whether the strength of smiling covaries with
emotional experience and physiological arousal (i.e.,
monotonicity hypothesis). This hypothesis predicts
that the relationship between intensity of facial ex-
pression and the emotional experience should be posi-
tive (Tourangeau & Ellsworth, 1979). Our results lend
largely support to this hypothesis in showing that the
Duchenne smile group reacted more positively while
viewing pleasant (landscape and chimpanzee stimuli)
and funny (Cartoons 1 and 2) videoclips compared
with the control group (except for the landscape
stimulus) and the lips-pressing group. They also re-
ported more positive emotional experience than did
participants who displayed non-Duchenne smiles for
three videoclips (i.e., pleasant stimuli and Cartoon 1).
Although the experimental evidence seems less
convincing for physiological arousal, enhanced auto-
nomic responding (i.e., skin conductance and heart
rate) were nevertheless detected but only in partici-
pants displaying Duchenne smiles and viewing one of
the positive videoclips (significance for Cartoon 1,
greater increase for three videoclips). An increase in
autonomic arousal has been often demonstrated in
participants whose expressive behavior was facilitated
(Colby et al., 1977; Hess et al., 1992; Lanzetta et al.,
1976; Levenson et al., 1990; Putnam, Winton, &
Krauss, 1982; Zuckerman et al., 1981). For instance,
when people were instructed to produce facial con-
figurations of happiness, skin conductance increases
and heart rate changes were observed (Levenson et al.,
1990). It is unclear, however, why autonomic differ-
ences were not detected in our study for the other
positive videoclips when Duchenne smiles were com-
pared with the other facial configurations. A possible
explanation is that participants induced not to display
a smile (control group and lips-pressing group) while
watching positive videoclips were likely in a condi-
tion of suppression of expressive behavior. Gross and
Levenson (1997) have shown that suppression of fa-
cial expression while participants watched amusing
films elicited a mixed physiological state character-
ized by decreased heart rate (due to a low somatic
activity), along with increased sympathetic activation.
Our findings of autonomic responding in no-smiling
groups are just like those described by these authors
(i.e., increase of skin conductance, decrease of heart
rate). Thus, although the Duchenne smile group
showed autonomic activation for the positive video-
clips, there is also evidence of a slight sympathetic
activation (i.e., increase of skin conductance) in par-
ticipants induced to display no expressive behavior
while they experienced positive emotion. Whether
this explanation is well-grounded requires additional
research. In the future, it would be important to in-
clude neutral videoclips to test the effect of suppres-
sion of smiling behavior on autonomic patterns.
Taken as a whole our findings yield support for the
monotonicity hypothesis. This assumption would be
consistent with previous research, which has usually
assessed the monotonicity hypothesis by comparing
faces with and without emotional actions (e.g., Hess
et al., 1992). A more stringent way to test the mono-
tonicity hypothesis (i.e., a stringent version of this
hypothesis) would be to verify whether the degree of
contraction of specific muscular actions (e.g., increase
in the intensity of zygomatic action) contribute to in-
crease subjective experience of emotion and physi-
ological arousal. In our study, the lack of difference
for the self-report and autonomic data between par-
ticipants displaying distinct intensities of zygomatic
action (i.e., C-level vs. D-level n-DSG) does not sup-
port a stringent version of the monotonicity hypoth-
esis. However, the number of participants exhibiting
intense zygomatic action was small, so the findings
must be cautiously interpreted. The question of
whether the differential contraction of zygomaticus
major muscles alone may enhance emotional states
should be considered more systematically in future
research.
Bearing in mind this methodological issue, the third
question we addressed in this study was whether the
morphology of smiling facilitates the subjective and
physiological components of emotion. The compari-
son between the Duchenne smile group and the non-
Duchenne smile group displaying the same intensity
of zygomatic action (D-level n-DSG) suggested that
the presence of the Duchenne marker alone (i.e., or-
bicularis oculi action) increased the intensity of posi-
tive emotional experience in participants who were
DUCHENNE SMILE AND EMOTIONAL EXPERIENCE 69
viewing pleasant and funny videoclips. Although less
clear-cut findings were obtained for autonomic mea-
sures, Duchenne smiling increased skin conductance
(for landscape videoclip) and heart rate (for chimpan-
zee videoclip and Cartoon 1) as compared with the
high-level non-Duchenne smiling (D-level n-DSG).
Thus, one may assume that the additional activation
of orbicularis oculi muscles, which are responsible for
the presence of crow’s feet wrinkles at the outer edges
of eyes, provides an input for mediating the observed
emotional changes. It is interesting that the Duchenne
smile has been often considered as a felt or enjoyment
smile, whereas the non-Duchenne smile has been de-
scribed as an unfelt smile (Ekman & Friesen, 1982;
Frank et al., 1993). Pleasant stimuli (e.g., films,
odors), affiliative interactions, and success in achieve-
ment games were shown to elicit more often smiles
with the Duchenne marker than other types of smiles
(Ekman et al., 1990; Fox & Davidson, 1988;
Schneider & Unzner, 1989; Soussignan & Schaal,
1996b). Furthermore, EMG activity over the orbicu-
laris oculi muscle regions differentiated not only the
pleasantness of stimuli (Cacioppo et al., 1986, 1992)
but also participants seeing a Duchenne smile versus
those seeing a non-Duchenne smile (Surakka & Hi-
etanen, 1998). The data of the present study confirm
the validity of the morphological and functional dif-
ferentiation between Duchenne and non-Duchenne
smiles. They support the notion that facial action pat-
terns that closely match specific facial prototypes
have a greater influence on emotional experience
(Levenson et al., 1990). These findings may explain
why some psychophysiological studies did not report
any relationship between zygomatic activity and self-
report of pleasantness (e.g., Cacioppo et al., 1992;
Fridlund, 1991). They are also compatible with a re-
cent study showing no change in self-report of posi-
tive emotion in patients with facial neuromuscular
disorders whose smiling was impaired (VanSwearin-
gen, Cohn, & Bajaj-Luthra, 1999).
A final issue we addressed in this study was the
examination of the influence of stimulus characteris-
tics (i.e., valence and intensity) on the facially modu-
lated components of emotional systems. When par-
ticipants produced Duchenne smiles only, a stronger
facial effect was predicted for positive versus negative
scenes. As expected, a congruent effect between Du-
chenne smiling and emotion-eliciting events was
clearly supported for self-reported emotional experi-
ence and, partly, for autonomic nervous system reac-
tivity. This effect was already postulated by a number
of authors who hypothesized that adding congruent
cognition (e.g., attention processes, semantic informa-
tion) to expressive behaviors would provide a potent
procedure for testing the modulating function of facial
patterns (e.g., Izard, 1990). Thus, one may hypoth-
esize that powerful feedback effects would depend on
the interaction of muscular action patterns with con-
gruent contextual and cognitive factors. It is interest-
ing that research on mood congruence, which inves-
tigates the influence of affective state on memory,
also provides empirical evidence in favor of this hy-
pothesis. For instance, people exposed to a pleasant
smell recalled more happy memories than did people
exposed to an unpleasant smell (Ehrlichman & Halp-
ern, 1988). So, it is likely that congruence between the
hedonic valence of eliciting events and the self-
generated cues (e.g., semantic information in
memory, sensory feedback from the face) contribute
to bias the subsequent response (e.g., retrieval, self-
report measure of emotion experience, autonomic
measures). One speculative hypothesis that could ac-
count for these findings would be that cognitively
mediated positive experience (i.e., perception and ap-
praisal of stimuli) and sensory feedback processes
(e.g., via proprioceptive or cutaneous impulses) acti-
vate common neural pathways involved in the inte-
grated experiential and autonomic output (e.g., cor-
tico-limbic network).
Concerning the contribution of the intensity dimen-
sion of eliciting events in the facial modulation of
emotion, a greater facilitating effect during the pre-
sentation of strongly positive videoclips was ex-
pected. This hypothesis was not confirmed because
Duchenne smiling effects for emotional experience
and psychophysiological measures did not differenti-
ate between mildly and strongly positive videoclips.
Concerning our failure to find subjective and auto-
nomic differences between the smiling groups while
participants were shown Cartoon 2, no clear explana-
tion can be proposed. However, it can be noted that
this videoclip induced the strongest positive experi-
ence in both the stimulus selection and testing proce-
dures. Thus, a ceiling effect cannot be completely
ruled out. This assumption would be consistent with
the view that when funny videoclips evoke extreme or
very strong positive experience, facial feedback
would be less powerful to produce significant
changes. Further research is needed to examine
whether the facial feedback effect of smiling varies as
a function of the intensity of positive experience (e.g.,
amusement feeling).
In the present study, a number of methodological
issues were taken into account, including partialling
SOUSSIGNAN70
out possible confounds (i.e., unpleasantness and dif-
ficulty of the pencil-holding tasks). Furthermore, it
was demonstrated that the slight unpleasantness gen-
erated by the pencil-holding procedure was not a di-
rect function of the type of facial configuration dis-
played. Thus, it is unlikely that emotional ratings were
contaminated by differences between the pencil-
holding techniques. In addition, as the muscular effort
due to the difficulty of the task appeared to be at the
same level in the five experimental groups, it is also
unlikely that the observed subjective and autonomic
changes were produced by muscular effort alone. This
is corroborated by the lack of significant correlations
between emotional ratings and task difficulty on the
one hand, and emotional ratings and task unpleasant-
ness on the other hand. Finally, the cardiac–somatic
coupling usually invoked did not seem to be a critical
factor of variation because the levels of facial activity
generated by the pencil holding did not produce heart
rate acceleration when the emotional stimuli were ab-
sent.
Some speculative propositions about the putative
mechanism involved in the facial feedback effects re-
ported in this study can be proposed. Because the
experimental paradigm used in this research rules out
mechanisms based on cognitive processes (e.g., self-
perception, compliance with experimental demand), it
is possible that physiologically driven mechanisms
(e.g., muscular proprioceptive patterns, cutaneous
sensation) mediate the observed effects. Available
electrophysiological data in humans showed that
mechanoreceptors of the facial skin respond to the
deformation associated with lip and jaw movements,
suggesting that facial movements may provide pro-
prioceptive information (Johansson, Trulsson, Olson,
& Abbs, 1988). Therefore, it is likely that sensory
input generated by Duchenne smiling was automati-
cally and rapidly processed outside conscious cogni-
tive mediation. This afferent information may, then,
contribute to the on-line modulation of the cognitively
integrated emotional experience resulting from the
perception of eliciting events. Although the neural
substrate of this mechanism is not clearly understood,
some structures such as somatosensory cortices have
been proposed to account for the processing of facial
and bodily cues involved in the experience of emo-
tional state (Damasio, 1995; Damasio et al., 2000).
Finally, limitations in generalizability of our data
must be acknowledged because our sample was com-
posed of female participants only. Although research
has not systematically addressed the issue of gender
difference in facial feedback mechanisms, much re-
search found effects in mixed-gender samples (see
McIntosh, 1996). Further research is required to de-
termine whether the facilitating effect of Duchenne
smiling varies as a function of gender.
In conclusion, the findings of the present research
suggest that the sensory input provided by Duchenne
smiling contribute to the formation of positive feel-
ings and, to some extent, to autonomic nervous sys-
tem responsiveness. This was observed when partici-
pants focused their attention on pleasant and funny
events. Additional research, of course, is needed to
further explore the factors and mechanisms involved
in the facial feedback effects. It would be particularly
important to design unobtrusive paradigms that could
be applied to the study of facial configurations repre-
senting other valid analogs of emotion.
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Received March 5, 2001
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Accepted December 6, 2001
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... The orbicularis oculi causes a lifting of the cheeks, a narrowing of the eye opening, and wrinkles around the eyes. The combination of zygomaticus major contraction, along with orbicularis oculi contraction, is sometimes indicative of positive emotion (Frank et al. 1993;Soussignan 2002). The perceiver of the "Duchenne" smile also interprets it as expressive of positive emotion (Miles & Johnston 2007) and may respond to it with positive affect (Surakka & Hietanen 1998). ...
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... Link to corresponding emotions. As anticipated by facial feedback theory, facial mimicry may be accompanied by self-reports of a corresponding emotion, sometimes called emotional contagion (Hatfield et al. 1992;Laird et al. 1994;Strayer 1993;Wild et al. 2001;Soussignan 2002). For afferent feedback to contribute to an embodied simulation of a perceived smile, however, the perceiver does not necessarily have to experience a conscious change in emotional state -such simulations often appear to have unconscious impact. ...
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... Additionally measuring the activity of the orbicularis oculi pars lateralis would allow us to shed light on the hypotheses regarding zygomatic activity in response to auditory expressions of fear in the blind. The activity of the orbicularis oculi presented along with zygomatic activity would suggest a genuine smile (Soussignan, 2002). No such pattern could be a sign of using a smile to mask a response to negative stimuli. ...
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... The Social Smile has been well investigated in literature and has been associated with the morphological conformation of the communicative smile, perceived as more intense and expressive [56,57]. Within the first early interactions between the child and the caregiver, the Social Smile is characterized by being perceived as a more intense expression, compared to Simple Smiles [57][58][59][60], and to occur more frequently in interactive periods in which infant's attention is directed towards the face of the smiling mother [46,61]. This communicative expression emerges very early in the developmental course and matures within the first semester of life, in conjunction with the acquisition of new visual attention patterns to social stimuli [47,62]. ...
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... The imitated behavior then induces the corresponding emotions (Hatfield et al. 1993). According to facial feedback theory, the facial mimicry of observed authentic expressions leads to stronger emotions, unlike the facial mimicry of inauthentic expressions (Soussignan 2002). Hennig-Thurau et al. (2006) show that these effects are valid in the context of service encounters. ...
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Research has shown that while the authenticity of positive emotional displays plays an important role in service encounters, it has not yet demonstrated a universally positive effect on customers' behavior. This study, which is the first to present customer involvement as a contextual factor that influences customers' processing, provides a deeper understanding of the effectiveness of the authenticity of emotional displays. The model is based on expectation disconfirmation theory and emotional contagion theory and is validated in a field experiment and two laboratory experiments that use video stimuli with actors in real-world contexts. The results show that even inauthentic displays can meet customers' expectations depending on their involvement and that high-involvement customers adapt to employees' authentic emotions more strongly than low-involvement customers do. In summary, the presented model strengthens the understanding of the role of authentic displays and provides an approach to improve the effectiveness of emotional labor strategies.
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This study examined the relationship between smile type and play type during parent-infant interactions in the home. Thirty-six mother-infant and father-infant dyads were videotaped playing for 10 min. Smile type (basic, Duchenne, and duplay smiles) and play type (object, physical, vocal, and book reading) were coded. Results of loglinear analysis indicated that different types of smiles occur during different types of play more often than expected if distributed equally. In addition, different smile-type and play-type patterns occurred for father-infant dyads compared with mother-infant dyads. Qualitative analyses were used to generate hypotheses about the reasons why different types of smiles occurred during various play activities.
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The vascular theory of emotional efference (VTEE) states that facial action can alter the volume of air inhaled though the nose, which in turn influences brain temperature and affective states. Cooling enhances positive affect, whereas warming depresses it. Three studies assessed this hypothesised series of effects. Study 1 found that when subjects engaged facial muscles in a manner analogous to a negative emotional expression, the volume of ambient air inhaled through the nose decreased, forehead temperature (a measure of brain temperature) increased, and participants reported feeling more negative affect. Study 2 established that prevention of nasal breathing generated negative affect. Study 3 indicated that forehead temperature increased when nasal breathing was prevented, without forehead muscle movement. Further, facial movement and prevention of nasal inhalation had no effects on arm temperature, showing that facial movement has only locally specific temperature effects. The hypotheses generated from VTEE were thus generally supported, and suggest a means by which facial action can cause changes in affective state in the absence of cognitive appraisal.
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Achievement-oriented behavior was characterized by the pioneers of achievement motivation research as “competition with a standard of excellence” (McClelland, Atkinson, Clark, & Lowell, 1953). Competing with a standard of excellence is manifested in such behaviors as the choice of difficulty levels in trying different tasks, or different task difficulty levels of one and the same task, and in the amount of effort and persistence invested in task performance. The motivation causing these behaviors was defined by Heckhausen as “the striving to increase, or keep as high as possible, one’s own capability in all activities in which a standard of excellence is thought to apply and where the execution of such activities can, therefore, either succeed or fail” (Heckhausen, 1967, p. 5).
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Facial responsiveness to pleasant and unpleasant odors was examined in 5- to 12 year-old children in either an alone condition (AC) or a social presence condition (SPC). The children failed to display reflex-like patterns, but they exhibited facial configurations that varied according to the odor valence and the social condition. Girls evinced more smiles than did boys, but this sex difference was significant only in response to unpleasant odors in the SPC. Furthermore, untrained observers were able to accurately identify the children's facial responses to unpleasant odors in the AC only and to pleasant odors in the SPC only. These findings (a) suggest that facial responsiveness to odors is flexible and able to reorganize when display rules operate and (b) support the emotional and communicative functions of human facial behavior.
Article
Naturalistic observation at a bowling alley (N = 1,793 balls) shows that bowlers often smiled when socially engaged, looking at and talking to others, but not necessarily after scoring a spare or a strike. In a 2nd study, bowlers (N = 166 balls) rarely smiled while facing the pins but often smiled when facing their friends. At a hockey game, fans (N = 3,726 faces) smiled both when they were socially involved and after events favorable to their team. Pedestrians (N = 663) were much more likely to smile when talking but only slightly more likely to smile in response to nice weather than to unpleasant weather. These 4 studies suggest a strong and robust association of smiling with a social motivation and an erratic association with emotional experience. (29 ref) (PsycINFO Database Record (c) 2006 APA, all rights reserved).