can duchenne smiles be feigned

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Can Duchenne Smiles Be Feigned?New Evidence on Felt and False Smiles

Eva G. KrumhuberUniversity of Geneva

Antony S. R. MansteadCardiff University

We investigated the value of the Duchenne (D) smile as a spontaneous sign of felt enjoyment.

Participants either smiled spontaneously in response to amusing material (spontaneous condition) or were

instructed to pose a smile (deliberate condition). Similar amounts of D and non-Duchenne (ND) smiles

were observed in these 2 conditions (Experiment 1). When subsets of these smiles were presented to other

participants, they generally rated spontaneous and deliberate D and ND smiles differently. Moreover,

they distinguished between D smiles of varying intensity within the spontaneous condition (Experiment

2). Such a differentiation was also made when seeing the upper or lower face only (Experiment 3), but

was impaired for static compared with dynamic displays (Experiment 4). The predictive value of the D

smile in these judgment studies was limited compared with other features such as asymmetry, apex

duration, and nonpositive facial actions, and was only significant for ratings of the upper face and static

displays. These findings raise doubts about the reliability and validity of the D smile and question the

usefulness of facial descriptions in identifying true feelings of enjoyment.

Keywords: emotion, facial expression, Duchenne smile, smile perception

According to discrete emotion theory, facial expressions show

emotions and are intrinsically linked to feelings (Ekman, 1982,

1992a). In this research tradition, the Duchenne (D) smile has been

proposed as a spontaneous and genuine expression of positive

emotions such as happiness, pleasure, or enjoyment (Ekman,

1992b; Ekman, Davidson, & Friesen, 1990; Frank & Ekman,

1993). This type of smile is named after the French neuroanatomist

Duchenne de Boulogne who described the smile and suggested

that it is “put into play by the sweet emotions of the soul . . .”(Duchenne, 1862/1990, p. 72). In the Facial Action Coding System

(FACS; Ekman & Friesen, 1978; Ekman, Friesen, & Hager, 2002),

a system for coding visible facial movements, the appearance of

the D smile has been classified as a combination of two facial

muscle movements: the zygomaticus major muscle (Action Unit

[AU] 12 in FACS), which pulls the lip corners up, thereby pro-

ducing a smiling mouth, and the orbicularis oculi , pars lateralis

muscle (AU 6 in FACS), which causes a lifting of the cheeks,

narrowing of the eye opening, and wrinkles around the eye socket

colloquially called crow’s feet .

It has been argued that only smiles that involve both facial

actions (i.e., D smiles) should be regarded as spontaneous, felt

smiles and as indicators of a positive emotion. In contrast, the

orbicularis oculi action (AU 6) should be absent in false or vol-

untary smiles (Ekman, 1993; Ekman & Friesen, 1982), which

involve movement only in the mouth region (AU 12, non-

Duchenne [ND] smiles). These false smiles have also been labeled

social, polite, or masking smiles (Ekman, 1989). Although the

motives for posed smiles vary, their common function is to con-

vince another person that enjoyment is occurring when it is not

(Ekman & Friesen, 1982; Frank, Ekman, & Friesen, 1993).It is argued that this distinction between smile types has its

origins in different neural pathways (Frank & Ekman, 1993; Rinn,

1991). Most people are able to activate the zygomaticus major

muscle voluntarily; by contrast, the upper face muscles are less

involved in learned activities, with most people (80%) being

unable to contract the orbicularis oculi, pars lateralis muscle vol-

untarily (Ekman, Roper, & Hager, 1980; Levenson, Ekman, &

Friesen, 1990). The orbicularis oculi muscle (AU 6) involved in D

smiles has consequently been labeled a reliable muscle (Ekman,

1993, p. 390). Because this muscle is difficult to control, it is not

available for use in false expressions (Ekman, 1985, 1989); there-

fore, it provides a reliable and spontaneous sign of enjoyment. The

present research focused on this voluntary aspect and investigated

how reliable and valid the D smile actually is with respect to itsexpression and perception.

The Expression of Duchenne Smiles

There is evidence that D smiles occur when positive emotions

are elicited and when people enjoy themselves. Specifically, D

smiles are shown more often (than ND smiles) in response to

pleasant stimuli (Ekman et al., 1990; Soussignan & Schaal, 1996)

and when positive feelings such as amusement and enjoyment are

reported (Ekman, Friesen, & O’Sullivan, 1988; Frank et al., 1993).

D smiles are also associated with self-reports of love and good

Eva G. Krumhuber, Swiss Center for Affective Sciences, University of

Geneva; Antony S. R. Manstead, School of Psychology, Cardiff Univer-

sity.

We thank Magdalena Cholakova and Nicoletta Dimitrova for their help

with Experiment 1 and Gwenda Simons for FACS coding. We are grateful

to Paula Niedenthal, Geoff Thomas, and two anonymous reviewers for

valuable comments on previous versions of this article.

Correspondence concerning this article should be addressed to Eva

Krumhuber, Swiss Center for Affective Sciences, CISA—University of

Geneva, 7 Rue des Battoirs, 1205 Geneva, Switzerland. E-mail:

[email protected]

Emotion © 2009 American Psychological Association2009, Vol. 9, No. 6, 807– 820 1528-3542/09/$12.00 DOI: 10.1037/a0017844

807



mood (Gonzaga, Keltner, Londahl, & Smith, 2001; Scherer &

Ceschi, 2000), marital satisfaction (Harker & Keltner, 2001), and

health improvement in clinical populations (Ekman, Matsumoto,

& Friesen, 1997; Steiner, 1986). In children, more D smiles (than

ND smiles) occur in response to a familiar adult (Fox & Davidson,

1988), when children are gazing at their smiling mother (Mess-

inger, Fogel, & Dickson, 1999, 2001), and during success in anachievement game (Schneider & Unzer, 1992).

These studies show that D smiles tend to be shown under

circumstances of spontaneously experienced positive affect. How-

ever, there is also evidence that D smiles occur in posed and

negative contexts. Specifically, D smiles have been observed both

when participants smiled spontaneously and when they were in-

structed to do so (Schmidt, Ambadar, Cohn, & Reed, 2006). For

such posed smiles, the majority of the participants have been found

to show orbicularis oculi—AU 6—activation (Schmidt, Bhatta-

charya, & Denlinger, 2009; Smith, Smith, & Ellgring, 1996); in

one study of 105 posed smiles, 67% were found to be D smiles

(Schmidt & Cohn, 2001). D smiles have also been found to occur

in response to negative film clips (Ekman et al., 1990), when

negative emotions are being concealed (Ekman et al., 1988), afterfailure in a game (Schneider & Josephs, 1991; Zaalberg, Manstead,

& Fischer, 2002), during tickling in the absence of positive affect

(Harris & Alvarado, 2005), in expressions of embarrassment (Kelt-

ner, 1995), and when talking about negative events (Lee & Beattie,

1998). Bonnano and colleagues observed D laughter and smiles

when participants talked about a recently deceased spouse (Keltner

& Bonanno, 1997) and in response to a negative affect manipula-

tion during a monologue task (Papa & Bonanno, 2008). It is

interesting that these D expressions and only these D expressions

were related to a reduction or dissociation of negative affect and to

better social relations at a later time. Ansfield (2007) suggested

that smiles serve a self-regulatory function of coping with negative

emotional experiences. In his study, the more participants smiledwhile viewing distressing videos, the more positive affect they

reported afterward. The D expression, whether made spontane-

ously or deliberately, may therefore foster positive self-regulation

and lead to relevant physiological and affective changes through

facial feedback mechanisms.

Supportive evidence comes from Soussignan (2002), who

showed that through the unconscious facilitation of D smiles by

having participants hold a pen between their teeth, self-reports of

positive experience, skin conductance, and heart rate in response to

pleasant film clips all increased. These associations were not found

for ND smiles of similar intensity. However, the conscious volun-

tary production of D smiles by muscle-by-muscle instruction has

also been shown to generate relevant physiological changes (Ek-

man & Davidson, 1993). When contracting the zygomaticus majorand the orbicularis oculi, pars lateralis muscles on command,

patterns of regional brain activity were similar to those of spon-

taneous displays of D smiles. Moreover, 32 of 45 undergraduates

(71.1%) could produce such deliberate D smiles.

Such findings suggest that D smiles exert a positive feedback on

subjective and physiological variables that resemble those occur-

ring during spontaneous positive affect. However, and in contrast

to what has been previously claimed, D smiles do not only occur

as a sign of genuine felt enjoyment. People can and do display D

smiles under deliberate circumstances and in the absence of pos-

itive feelings. The suggestion that 80% of the population would be

unable to voluntarily contract the orbicularis oculi, pars lateralis

muscle and thus be capable of producing a false D smile (Ekman

et al., 1990; Frank & Ekman, 1993) should therefore be treated

with caution. Indeed, the evidence generally cited in support of this

suggestion comes from observations and research with young

children in whom AU 6 was not measured at all (Ekman et al.,

1980) or from studies showing that happy D smiles were ratedactually as the easiest configuration to produce deliberately by

trained actors, college students, and local people (Levenson et al.,

1990).

The Perception of Duchenne Smiles

There are several studies showing that D and ND smiles are

perceived differently. Individuals displaying D smiles are evalu-

ated as more emotional and interpersonally positive (Frank et al.,

1993; Harker & Keltner, 2001; Messinger, Cassel, Acosta, Amba-

dar, & Cohn, 2008), as being in better humor (Scherer & Ceschi,

2000), and as expressing more pleasantness (Soussignan & Schaal,

1996) than their ND smiling counterparts. D smiles also elicit more

positive emotional and affiliative responses in other people(Gonzaga et al., 2001; Keltner & Bonanno, 1997; Surakka &

Hietanen, 1998), contribute to perceptions of greater spontaneity

and authenticity (Gosselin, Beaupre, & Boissonneault, 2002; Gos-

selin, Perron, Legault, & Campanella, 2002; Giudice & Colle,

2007; Hess & Kleck, 1994), and lead to more positive evaluations

of peripheral, unrelated attributes (Peace, Miles, & Johnston,

2006).

It is interesting that contraction of the orbicularis oculi muscle

occurs in negative emotions, not only in positive ones. Ekman and

Friesen (1982) noted that the outer part of the orbicularis oculi

muscle is also involved when distress, pain, or sadness are felt.

Messinger and colleagues (Bolzani Dinehart et al., 2005; Mess-

inger, 2002) showed that eye constriction (AU 6) had significanteffects on raters’ perceptions of the intensity of positive emotions

as well as negative ones. In particular, when eye constriction

accompanied infants’ smiles, it made positive expressions appear

more positive; when it accompanied cry faces, it made these

expressions appear more negative. The same facial movement was

therefore seen as signaling increased intensity in two qualitatively

different emotions. A further complexity is that the D smile can

also occur in conjunction with facial features (i.e., frowning,

dimpling, lip tightening, lip corner depressing) indicative of neg-

ative emotions (Ekman, 1985). Such modulations of smiling have

been found in spontaneous as well as in deliberate or social smiles

(Schmidt, Cohn, & Tian, 2003; Schmidt et al., 2009) and have

been shown to influence observers’ ratings of the happiness and

amusement of the sender (Ambadar, Cohn, & Reed, 2009; Gosse-lin, Beaupre, & Boissonneault, 2002; Hess, Kappas, McHugo,

Kleck, & Lanzetta, 1989). Therefore, neither the D smile nor its

distinctive feature, AU 6, is uniquely associated with the percep-

tion of positive emotion; both can co-occur with nonpositive facial

actions.

Furthermore, factors other than the D marker have been pro-

posed as differentiating between spontaneous and happy and posed

smiles (see Frank & Ekman, 1993; Frank et al., 1993). One such

factor is the greater symmetry of spontaneous smiles. Several

studies found that smiles made spontaneously in reaction to an

experimenter’s joke or a pleasant film were more symmetrical than

808 KRUMHUBER AND MANSTEAD



were deliberate smiles made on request (Ekman, Hager, & Friesen,

1981; Hager & Ekman, 1997; Skinner & Mullen, 1991). Schmidt

et al. (2006, 2009), however, did not find the proposed difference

in symmetry, and other studies have failed to show an effect of

symmetry on perceivers’ ratings of happiness and amusement

(Ambadar et al., 2009; Gosselin, Perron, et al., 2002).

It has also been argued that spontaneous smiles are smootherthan their deliberate counterparts. Spontaneous smiles have been

found to be smoother and to contain fewer irregularities (pauses

and stepped intensity changes) than deliberate smiles (Hess &

Kleck, 1990; Weiss, Blum, & Gleberman, 1987). Smoothness

versus irregularity also has been shown to influence observers’

judgments of the degree of control of the expression (Hess &

Kleck, 1994). Furthermore, temporal parameters such as the rela-

tive durations of onset, apex, and offset phases of a smile have

been proposed to distinguish between spontaneous and deliberate

smiles. Some studies have found longer onset and offset times for

spontaneous smiles than for deliberate ones (Hess & Kleck, 1990;

Schmidt et al., 2006, 2009). Effects of onset, apex, and offset

durations have been demonstrated for ratings of smile genuineness

(Krumhuber & Kappas, 2005; Krumhuber, Manstead, Cosker,Marshall, & Rosin, 2009; Krumhuber, Manstead, & Kappas, 2007;

Krumhuber, Manstead, Cosker, et al., 2007), but not for accuracy

of expression discrimination or judgments of control when only

onset speed was considered (Hess & Kleck, 1994).

Of all the attributes of felt, genuine smiles, the D marker has

been proposed as the most reliable, robust, and diagnostic marker.

As Frank and Ekman (1993) stated, “All the other markers (i.e.,

symmetry, smoothness, duration) should be considered necessary,

but not necessarily sufficient indicators of an enjoyment smile” (p.

21). It is interesting that the signal value of the D smile rarely has

been studied alongside these other physical markers. In some

cases, only one feature (i.e., overall duration or symmetry or

nonpositive facial actions) was measured or manipulated in thepresence of the D smile, yielding evidence of the dominant role of

the D marker (Frank et al., 1993; Gosselin, Beaupre, & Boisson-

neault, 2002; Gosselin, Perron, et al., 2002). Hess and Kleck

(1994) explored a combination of cues, but their results pertained

more globally to spontaneous expressions, combining positive and

negative emotions. In a recent study by Ambadar et al. (2009), the

signal value of the D marker was tested in the context of other smile

characteristics such as asymmetry of amplitude, onset and offset

velocity, and nonpositive facial actions (called smile controls). Al-

though AU 6 occurred more often during smiles perceived to reflect

amusement than during polite or embarrassed smiles, the presence of

the D marker on its own was not sufficient to signify amusement.

How much the D smile, as opposed to other physical markers, affects

perceptions of positive emotion therefore remains unclear.

Present Research

The objective of the present research was to investigate the

reliability and validity of the D smile. As we have seen, there is a

widespread assumption that D smiles are spontaneous expressions

that reflect felt positive emotion. We aimed to test this assumption

systematically by investigating both spontaneous and deliberate D

and ND smiles. In a first experiment, we focused on the expression

of these different types of smile. Here, we studied whether and

how often people activated the orbicularis oculi , pars lateralis

muscle (AU 6) when smiling voluntarily. We also examined

whether D smiles occurred solely or predominantly under sponta-

neous conditions, and whether ND smiles occurred solely or pre-

dominantly under deliberate conditions. If the presence of AU 6 in

D smiles is a reliable sign of spontaneous enjoyment, it should not

occur in false or voluntary smiles. Moreover, senders should report

subjective experience of positive emotion when exhibiting Dsmiles, but not when exhibiting ND smiles.

In subsequent studies, we examined how D and ND smiles were

perceived, and whether people made different judgments of these

two smile types when they were made under spontaneous and

deliberate conditions. To date, no study has explored the percep-

tion of both spontaneous and deliberate D smiles. In a series of

experiments, we investigated perceivers’ ratings of these smiles

with respect to spontaneity, genuineness, and amusement. We also

examined whether judges differentiated between more and less

intense D smiles made in the spontaneous condition (Experiment

2), and whether ratings of smiles were affected by having access to

the upper versus the lower face (Experiment 3) or when seeing

static versus dynamic displays (Experiment 4). As well as this

focus on how smile types affected judgments, we tested the pre-

dictive value of the D marker alongside other behavioral features,

namely asymmetry; irregularity; onset, apex, and offset durations;

and nonpositive facial actions. If the D marker is the most diag-

nostic feature of an enjoyment smile, it should play a major role in

predicting how genuine and amused the smile is judged to be. We

therefore expected its utility in predicting the ratings of smiles in

Experiments 2–4 to be consistent and at least as great as (if not

greater than) the predictive value of the other physical attributes.

Experiment 1

The purpose of this study was to test the notion that D smilessignal spontaneous felt emotions, with AU 6 being a reliable

indicator of enjoyment (Ekman, 1993; Ekman & Friesen, 1982).

To this end, we compared the amount of D and ND smiles

exhibited under spontaneous and deliberate conditions and exam-

ined the levels of positive emotions that were reported by individ-

uals showing these smile expressions.

Method

Participants

Thirty-two undergraduate students (16 men, 16 women), ages

18 to 35 years ( M 22.59 years, SD 4.01) at Cardiff Universityparticipated on a voluntary basis and were paid £3.

Materials and Procedure

In the spontaneous condition, participants saw six amusing

stimuli intended to induce positive emotional feelings. The stimuli

consisted of two jokes, one cartoon, and three film clips, each of

which was approximately 15 s in length. They were selected from

a larger pool of 34 stimuli that had been pretested on 19 partici-

pants (9 women, 10 men, ages 20–26 years, M 22.65 years,

SD 2.06) for their capacity to evoke amusement ( M 5.37),

809FELT AND FALSE SMILES



pleasure ( M 4.54), and happiness ( M 4.45) on a 7-point rating

scale (1 not at all, 7 extremely).1 Apart from one joke that had

been used in a previous study, all stimuli were chosen from the

Internet (e.g., http://www.allfunnypictures.com). The amusing

stimuli were separated by filler items, that is, pictures of inanimate

objects drawn from the International Affective Picture System (IAPS;

Lang, Bradley, & Cuthbert, 2001) that had low arousal and neutralvalence scores ( M 2.49 and M 4.89, respectively, on a 9-point

scale). These filler stimuli were presented for 8 s each and were

intended to return participants to a neutral emotional state.

In the deliberate condition, participants saw a different set of six

IAPS slides of inanimate objects that had low arousal ( M 2.47)

and neutral valence scores ( M 5.01) and were intended to serve

as neutral stimuli. Each neutral stimulus was presented for 10 s.

Following Hess and Kleck (1990), participants were instructed to

pose in front of the video monitor an expression that made it look

as if they were watching something funny and in a way that would

be as convincing as possible. More specifically, they were asked

to smile as they would if they felt amused. They were not allowed

to talk and had to rely simply on positive facial expressions. To

motivate participants, an incentive of £10 was promised if theirsmile expressions proved to be the most convincing of those made

by all participants (see Ekman et al., 1988; Schmidt et al., 2003, for

a similar procedure). The experimenter was not present during

either condition.

Participants always completed the spontaneous procedure first.

The rationale for this is the same as the one offered by Ekman et

al. (1988, 1990), namely that the reverse order would be likely to

result in interference effects between the two conditions. Within

each condition, the stimuli were presented in one of two different

sequences using MediaLab (Empirisoft) software. Participants

were asked to consent to being video recorded at the start of the

session, and their facial behavior was recorded during the whole

procedure. We also asked for participants’ permission to use thevideo recordings of their behavior in future research projects.

Apart from three people who objected to the future use of their

recordings, all participants agreed to both requests.

Dependent Variables

Facial action units. For each participant, the first smile that

occurred in each of the six spontaneous and six deliberate epochs

was selected for analysis to ensure a balanced representation of

smiles (for a similar approach, see Cohn & Schmidt, 2004;

Schmidt et al., 2003, 2006). This resulted in a set of 384 smiling

episodes. Facial activity during these episodes was scored using

the FACS (Ekman & Friesen, 1978; Ekman et al., 2002). FACS

enables the measurement of all visible facial behavior and de-scribes it in terms of 44 action units. For the purposes of the

present research, two of these action units, AU 12 and AU 6, were

treated as the primary dependent variables (for a similar procedure,

see Papa & Bonanno, 2008; Schmidt et al., 2006). AU 12 refers to

activity of the zygomaticus muscle and involves a lip corner pull

(smiling mouth). AU 6 refers to activity of the orbicularis oculi ,

pars lateralis muscle that raises the cheeks, gathers the skin around

the eye, and produces crow’s feet wrinkles. Smile episodes that

included both AU 12 and AU 6 were defined as D smiles, whereas

episodes that included only AU 12 were defined as ND smiles (cf.

Frank et al., 1993).

For all samples in the spontaneous and deliberate epochs, we

scored both the frequency of AU 12 and AU 6 and the maximum

intensity (1 trace to 5 maximum) that AU 12 reached during

each episode. Two FACS-trained coders who were blind to the

different stimulus sequences within condition individually coded

all the facial activity shown by the 32 participants. In addition, a

FACS-certified coder scored 50% of the samples (i.e., 192 smilingepisodes). Intercoder reliability was assessed as mean percentage

agreement (%) and chance-corrected Cohen’s kappa (). Intensity

differences of 1 point were treated as agreements (for a similar

approach, see Messinger et al., 2008). Mean agreement was

98.44% ( 0.94) for AU 12, 89.06% ( 0.79) for AU 6, and

96.35% ( 0.95) for AU 12 intensity, demonstrating high

reliability.

Subjective emotion. Immediately following each stimulus pre-

sentation, participants were asked to report the intensity with

which they had felt each of the following emotions while viewing

the stimulus just seen: amusement, pleasure, happiness, surprise,

and interest . Ratings were made on 7-point scales, with response

options ranging from 1 (not at all) to 7 (extremely). These ques-

tions were posed in a randomly selected order that varied with eachparticipant.

Results and Discussion

Preliminary analyses showed that neither stimulus type (jokes,

cartoon, film clips, pictures) nor the sequence in which the stimuli

were presented had an effect on any of the dependent variables

( ps .05). These factors were dropped from further analyses. For

each participant, frequency or average scores (intensity, emotion)

for D and ND smiles were computed in the spontaneous and

deliberate conditions. These four scores were entered into mixed

analyses of variance (ANOVAs) with two within-subjects factors,

condition (spontaneous, deliberate) and smile type (D, ND), andone between-subjects factor, sex of participant. Separate analyses

were carried out on the measures of facial activity (frequency,

intensity) and the measures of participants’ subjective emotion.

Facial Activity

ANOVA revealed a significant main effect of smile type on

frequency of smiling, F ( 1, 3 0) 33.92, p .001,

p2

.53. Overall, participants displayed more D (76.5%) than ND

smiles (23.3%). The condition main effect was not significant, F (1,

30) 2.14, p .05, p2

.07, nor was the interaction between

condition and smile type, F (1, 30) 3.81, p .05, p2

.11.

Overall, 70% of smiles in the spontaneous condition were D

smiles, and the remaining 30% were ND smiles. By comparison,83% of smiles in the deliberate condition were D smiles, and the

remaining 17% were ND smiles. Thus, D and ND smiles appeared

in approximately equal proportions in the spontaneous and delib-

erate conditions. This finding is consistent with evidence (Schmidt

& Cohn, 2001; Schmidt et al., 2006, 2009; Smith et al., 1996) that

1 Arousal scores for the six amusing stimuli used in the spontaneous

condition were below the midpoint ( M 2.82, SD 0.84, 7-point scale)

and similar to those of the stimuli used in the deliberate condition, as

indicated by an independent sample of 10 participants (5 men, 5 women),

ages 25 to 32 years ( M 28.9 years, SD 2.42).




people are able to pose a D smile deliberately, and that they do so

quite frequently. Thus, there is no direct evidence that AU 6 in D

smiles reflected spontaneity, whereas its absence in ND smiles

reflected deliberateness (Parkinson, 2005). The sex of participant

main effect was not significant, F (1, 30) 0.43, p .05,

p2

.01.

With respect to smile intensity, D smiles had higher intensitylevels ( M 3.11) than ND smiles ( M 0.97), F (1, 30) 106.67,

p .001, p2

.78, an effect observed by Ekman and Friesen

(1978) and also found in a recent study by Messinger et al. (2008).

The main effects of condition, F (1, 30) 0.01, p .05, p2

.00,

and sex of participant, F (1, 30) 1.37, p .05, p2 .04, were

not significant. However, there was a significant interaction be-

tween condition and smile type, F (1, 30) 8.52, p .01, p2

.22. Analysis of simple effects (see Winer, Brown, & Michels,

1991) showed that when participants were instructed to pose

smiles, D smiles were more intense ( M 3.37) than were D smiles

observed in the spontaneous condition ( M 2.85), F (1, 30)

5.67, p .05, p2

.16. Thus, participants were able to simulate

the D smile by putting on a strong smile that also activated the

upper facial muscles. The corresponding difference for ND smileswas not significant (spontaneous: M 1.24, deliberate: M

0.71), F (1, 30) 3.75, p .05, p2

.11.

Subjective Emotion

A factor analysis (principal components with varimax rotation)

of responses to the five emotion items showed that amusement,

pleasure, happiness, surprise, and interest all loaded on the same

factor (explaining 81.83% of the variance). They were therefore

combined to form a positive emotionality scale (Cronbach’s al-

pha .94). ANOVA showed significant main effects of condition,

F (1, 30) 53.78, p .001, p2

.64, and smile type, F (1, 30)

21.67, p .001, p

2

.42. Smiles shown in the spontaneouscondition were accompanied by significantly more positive emo-

tion ( M 3.03) than were those shown in the deliberate condition

( M 1.25), confirming that the elicitation procedures gave rise to

substantially different levels of positive affect. Participants also

reported having experienced significantly more positive emotion

during epochs in which they displayed D smiles ( M 2.84) than

in epochs in which they displayed ND smiles ( M 1.43). Thus,

smile type was also related to positive emotion. Consistent with the

notion that the D smile reflects true felt enjoyment (Ekman et al.,

1988, 1990; Frank et al., 1993), spontaneous D smiles were ac-

companied by more positive emotion ( M 3.74) than were

deliberate D smiles ( M 1.94), F (1, 30) 29.55, p .001, p2

.50. Similarly, spontaneous ND smiles were associated with more

positive emotion ( M 2.31) than were deliberate ND smiles ( M

0.55), F (1, 30) 22.89, p .001, p2

.43. The interaction

between condition and smile type was not significant, F (1, 30)

0.01, p .05, p2

.00, nor was the main effect of sex of

participant, F (1, 30) 3.79, p .05, p2

.11. Additional

correlation analyses showed a significant positive relationship

between degree of positive emotion and smile intensity, r (32)

.54, p .01.

Summarizing, neither D smiles nor ND smiles occurred solely

or predominantly under spontaneous or deliberate conditions.

Rather, whether or not a D smile was shown was associated with

the intensity of the expression and with the amount of positive

emotion experienced. In a series of judgment studies reported

below, we focused on the perception of smile expressions. Spe-

cifically, we investigated how D and ND smiles made under

spontaneous and deliberate conditions were perceived by naive

observers. Furthermore, we examined the extent to which the D

marker, along with other attributes (e.g., asymmetry; irregularity;

onset, apex, and offset durations; and nonpositive facial actions)predicted the ratings made by observers.

Experiment 2

Our aim in this study was to examine whether observers would

distinguish in their judgments between D and ND smiles that were

made under spontaneous and deliberate conditions. For example,

would D smiles originating from a spontaneous condition be rated

differently from those arising from a deliberate condition? If there

is only type of enjoyment smile, spontaneous D smiles should be

seen as more genuine than deliberate D smiles or spontaneous ND

smiles. An additional goal was to study the effects of expression

intensity on judgments of D smiles. Much research has shown that

the intensity of an expression significantly influences ratings of positive emotion (Bolzani Dinehart et al., 2005; Hess, Blairy, &

Kleck, 1997; Messinger, 2002; Messinger et al., 2008). We there-

fore wanted to test whether judges would distinguish between

spontaneous D smiles that differed in intensity. If the expression

intensity of the sender plays a role in the evaluation of D smiles,

more intense D smiles should be seen as reflecting greater subjec-

tive enjoyment than less intense D smiles.

Method

Participants

Fifty-two undergraduate students (22 men, 30 women), ages

18–33 years ( M 20.17 years, SD 2.25) at Cardiff Universitytook part in this study and were given either course credit or

payment of £2.

Stimulus Material and Design

It has been argued that the “true” spontaneous D smile should be

discernible mainly at a low or moderate intensity level, when the

smiling action of the mouth does not automatically lead to a

contraction of the upper face muscles, thereby giving the overall

appearance of a D smile (Ekman, 1985; Frank & Ekman, 1993).

The D and ND smiles selected from Experiment 1 were therefore

not of extreme intensity in FACS terms, but rather of slight or

moderate/pronounced intensity. We chose smiles that began and

ended with a neutral baseline expression and for which sendersreported having felt moderate or high emotions (i.e., pleasure,

amusement, and happiness ratings of 3 or higher on a 7-point scale

where 1 not at all and 7 extremely) in the spontaneous

condition and low or no emotions (i.e., pleasure, amusement and

happiness ratings of 2 and lower) in the deliberate condition (for a

similar procedure, see Hess & Kleck, 1994). From the pool of

smile expressions generated in Experiment 1, there were 30 smiles

of each type that met these criteria: (a) 6 spontaneous D smiles

(pronounced): M intensity 3.7, M positive emotion 5.2; (b) 6 spon-

taneous D smiles (moderate): M intensity 3.0, M positive emotion

3.8; (c) 6 spontaneous ND smiles: M intensity 2.2, M positive emo-




tion 3.9; (d) 6 deliberate D smiles: M intensity 3.5, M positive emotion 1.6;

and (e) 6 deliberate ND smiles: M intensity 2.0, M positive emotion 1.7.

Overall, the intensity of spontaneous D smiles was similar to that of

deliberate D smiles ( M 3.4 vs. M 3.5). The same was the case for ND

smiles, which did not differ with respect to intensity between the spontaneous

and deliberate conditions ( M 2.2 vs. M 2.0). In this way, we sought to

eliminate expression intensity as a possible explanation for differential re-sponses to smiles in the spontaneous and deliberate conditions (for a similar

approach, see Miles & Johnston, 2007; Peace et al., 2006; Soussignan, 2002)

and rather study the effects of expression intensity in the perception of

spontaneous D smiles (pronounced vs. moderate).2

In addition to the D marker, all 30 smiles were scored by two

FACS-certified coders who were blind to condition (i.e., sponta-

neous vs. deliberate) for the following behavioral features: Asym-

metry (mean agreement 93.34%; 0.86) was coded if the

smiling action was stronger on one side of the face (Ekman et al.,

1981). This was the case for deliberate ND smiles, which were

more asymmetric (83.3%) than both spontaneous D smiles (pro-

nounced) and spontaneous ND smiles (0.0% and 16.7%, p .01

and p .05), F (4, 20) 3.49, p .05, p2

.41.

Irregularity (mean agreement 90%, 0.75) was coded if the smile expression faded and reintensified or was characterized

by discontinuities in the onset, apex, or offset phases (Hess &

Kleck, 1990). No significant differences in irregularity occurred

between the five smile types, F (4, 20) 0.54, p .05, p2

.10.

Nonpositive facial actions (mean agreement 93.34%, 0.86)

were coded if frowning (AU 4), lip pressing (AU 24), dimpling (AU

14), lip corner depressing (AU 15), lid tightening (AU 7), or lower lip

depressing (AU 16) occurred during the smile. Such smile controls or

dampening movements (Ambadar et al., 2009; Schmidt et al., 2009)

previously have been associated with nonjoyful feelings (Ekman,

1985; Ekman et al., 2002). There were no significant differences in

the presence of nonpositive facial actions between the five smile

types, F (4, 20) 0.73, p .05, p

2

.13.Onset time, apex time, and offset time were coded by a FACS-

trained coder and a FACS-certified coder within a 0.5-s tolerance

window (see Sayette, Cohn, Wertz, Perrott, & Parrott, 2001) and

yielded high correlations between the two coders (intraclass r .79).

Onset duration was measured as the number of frames from the start

of the smile expression to its zenith. Apex duration was the number of

frames the smile expression was held at its peak, and offset duration

was measured as the number of frames from first evidence of decay

of the smile expression until it stopped decaying (Ekman et al., 2002;

Hess & Kleck, 1990). There were no significant differences between

the five smile types in onset duration, F (4, 20) 1.83, p .05, p2

.27, or offset duration, F (4, 20) 1.02, p .05, p2

.17. Onset

durations were on average 25.65 frames (1.03 s), whereas offset

durations were on average 49.80 frames (1.99 s). However, sponta-neous ND smiles were shorter in their apex durations ( M 12 frames,

0.48 s) than the other smile types ( M 90.79 frames, 3.63 s), F (4,

20) 12.04, p .001, p2

.71.

Correlation analyses of all smile features showed a significant

relationship only between temporal features of smiles. The longer the

onset, the longer the smile was held at its apex (r .37, p .05); the

longer the apex duration, the longer the offset (r .42, p .05).

Roughly the same number of smiles came from male and female

encoders (14:16). A given encoder could be shown more than once

with a different smile expression. On average, there were two smile

expressions per encoder that could be any of the types described

above. In this way, we tried to avoid presenting judges with a standard

baseline that they could rely on to rate the genuineness of an expres-

sion. The 30 smile expressions featuring five different types of smiles

were displayed as movie clips (750 576 pixels, 25 frames/s) in

MediaLab (Empirisoft) and shown in random order.

Procedure

After signing a consent form, participants were told that they

would see short video clips of several people. They were informed

that each person had been shown some amusing stimuli (e.g.,

funny pictures, movies, and texts) that were intended to elicit

positive emotional feelings and some neutral stimuli (i.e., pictures

of inanimate objects) that were intended to elicit no specific

emotion. They were further told that the amusing stimuli resulted

in smiles that were spontaneous and accompanied by genuine

amusement of the person, and that when presented with neutral

stimuli, the person viewing them had been asked to pose a smile as

if s/he was amused. We instructed participants to look carefully at

each smile and then to make judgments about it, including whether

it was spontaneous or posed. The video sequences were initiatedby using the mouse to click a Start button on the computer screen.

Dependent Variables

After each sequence, participants were asked to answer the

following questions on 7-point scales: (a) To what extent is the

smile you have just seen spontaneous or posed? (1 deliberate,

7 spontaneous), (b) to what extent is the smile you have just

seen genuine or fake? (1 fake, 7 genuine), and (c) to what

extent was the person you have just seen amused at the time of the

smile? (1 not at all, 7 very).


Analysis of Variance

A multivariate analysis of variance (MANOVA) with sex of

encoder and smile (five levels: pronounced spontaneous D, mod-

erate spontaneous D, spontaneous ND, deliberate D, deliberate

ND) as within-subjects factors and sex of participant as a between-

subjects factor was conducted on the three dependent variables

(spontaneous, genuine, and amused).3 There were no significant

effects associated with sex of encoder, F (3, 48) 0.28, p .05,

p2

.02, and this factor was dropped in further analyses. For all

2 Examples of the different types of smiles can be obtained from Eva G.

Krumhuber on request.3 Ratings of how spontaneous and genuine the smile appeared to be were

consistent and highly correlated with each other (r s .86, ps .001), and

analyses were virtually the same across all three experiments. Because

smile genuineness was theoretically the more important variable, we de-

cided to focus on this variable and report results for smile genuineness

only, not considering perceived spontaneity. The same applied to the

regression analyses in which the results were identical for measures of

spontaneity and genuineness. Ratings of spontaneity and genuineness were

associated with those of amusement (r s .46, p .001). However,

correlation coefficients were lower than those between spontaneity and

genuineness, suggesting that these two measures tap related but different

aspects of smile perception.




univariate analyses (spontaneous, genuine, amused), we applied a

Greenhouse–Geisser adjustment to degrees of freedom. The sex of

participant main effect was not significant, F (3, 48) 0.37, p .05,

p2

.02. As expected, there was a main effect for smile, F (12, 39)

32.16, p .001, p2

.91. It was significant for all three variables:

spontaneous, F (2.87, 143.74) 27.08, p .001, p2

.35; genuine,

F (3.09, 154.40) 27.93, p .001, p

2

.36; and amused, F (3.17,158.46) 135.35, p .001, p2 .73.

Post hoc comparisons showed that spontaneous D smiles were

generally rated as more genuine ( M diff 0.94, SE diff 0.18, ps

.001) and amused ( M diff 1.28, SE diff 0.12, ps .001) than ND

smiles, in accordance with previous findings (Frank et al., 1993;

Gosselin, Beaupre, & Boissonneault, 2002; Gosselin, Perron, et al.,

2000; Hess & Kleck, 1994; Messinger et al., 2008). It is interesting

that participants also distinguished between more intense and less

intense D smiles within the spontaneous condition. More intense D

smiles (i.e., pronounced) were judged as more genuine ( M diff

0.42, SE diff 0.12, p .05) and more amused ( M diff 0.82,

SE diff 0.08, p .001) than were D smiles of lower intensity (i.e.,

moderate; see Table 1, Experiment 2). Extending previous re-

search (Bolzani Dinehart et al., 2005; Hess et al., 1997; Messingeret al., 2008), these findings show that expression intensity leads to

differences in how spontaneous D smiles are perceived. The higher

the intensity of the expression, the more genuine and amused the

associated spontaneous D smile was perceived to be.

A different pattern of results was found for deliberate smiles.

Here, participants did not differ in their judgments of the genu-

ineness of D and ND smiles ( M diff 0.19, SE diff 0.18, p .05),

showing that they perceived these two types of smile as equally

insincere. They nevertheless made higher amusement ratings of D

than of ND smiles ( M diff 1.05, SE diff 0.12, p .001), thereby

providing some support for the notion that D smiles convey greater

positive emotionality.

Post hoc comparisons showed that there was a significant dif-ference in judgments of D smiles made under spontaneous and

deliberate conditions. Spontaneous D smiles attracted significantly

higher genuineness ( M diff 0.70, SE diff 0.16, ps .001) and

amusement ( M diff 0.88, SE diff 0.09, p .001) ratings than

deliberate D smiles. This is consistent with the assumption that

there is one type of genuine, felt smile: the spontaneous D smile.

No such difference emerged for ND smiles (genuine: M diff 0.05,

SE diff 0.14, p .05; amused: M diff 0.17, SE diff 0.09, p

.05), showing that elicitation condition had a significant impact

only on judgments of D smiles.

Regression Analyses

Multiple regression analyses were used to examine the degree to

which each of the facial features (D marker, asymmetry, irregu-

larity, onset time, apex time, offset time, nonpositive facial ac-

tions) predicted ratings of spontaneity, genuineness, and amuse-

ment. Table 2 (Experiment 2) shows the beta coefficients

associated with these seven predictors. Apex duration ( ps .05),

nonpositive facial actions ( ps .05), and asymmetry ( ps .05)

were significant predictors of how genuine and amused the smile

was perceived to be. The longer the apex duration and the fewer

nonpositive facial actions, the more genuine and amused a smile

was judged to be. Less asymmetry was also associated with higher

ratings of smile genuineness. Thus, symmetrical smiles were as-sociated with higher ratings of genuineness of the expression. The

presence or absence of the D marker did not significantly predict

any of the ratings, nor did irregularity, onset time, or offset time

( ps .05).

Experiment 3

Our aim in Experiment 3 was to investigate whether judgments

of smiles would be affected by having access to the upper or lower

face. Research on the relative importance of the upper and lower

face has shown either the mouth region (Bassili, 1979; Kersten-

baum, 1992) or both the mouth and the cheeks (Boucher & Ekman,

1975; Kohler et al., 2004; Nusseck, Cunningham, Wallraven, &Bulthoff, 2008) to be crucial to the recognition of happiness.

However, these studies did not specifically examine D smiles.

Williams, Senior, David, Loughland, and Gordon (2001) showed

more frequent and longer eye fixations to the crow’s feet area in

Table 1

Means and Standard Errors for Ratings of Genuineness and Amusement as a Function of Condition and Smile Type in Experiments

2, 3, and 4

Measure

Spontaneous Deliberate

Duchenne (b) Duchenne (a) Non-Duchenne Duchenne Non-Duchenne

M SE M SE M SE M SE M SE

Experiment 2 (n 53)Genuine 4.42a 0.12 4.83b 0.12 3.47c 0.14 3.71c 0.12 3.52c 0.11Amused 3.84a 0.10 4.66b 0.09 2.56c 0.08 3.77a 0.09 2.73c 0.08

Experiment 3 (n 50)Genuine — — 4.82a 0.11 3.41b 0.13 4.08c 0.10 3.36b 0.12Amused — — 4.68a 0.10 2.54b 0.09 3.85c 0.09 2.74d 0.10

Experiment 4 (n 60)Genuine — — 4.61a 0.11 3.37b 0.12 3.91c 0.09 3.57d 0.10Amused — — 4.56a 0.09 2.66b 0.09 3.91c 0.08 2.86d 0.09

Note. Duchenne (a) pronounced, more intense smiles; Duchenne (b) moderate, less intense smiles. All ratings were made on 1-to-7 Likert scales,with higher scores indicating greater levels of that dimension. Row means with different subscripts differ at p .05 or better.




the upper face of D smiles, but their findings pertain to compari-

sons with nonexpressive faces rather than with ND smiles. Trem-

blay et al. (1993) used image manipulation techniques to vary the

presence or absence of the D marker in still photographs of smiling

or neutral faces. Although crow’s feet (a distinctive feature of D

smiles) influenced perceptions of smile genuineness, this was only

in the case for medium intensity smiles. In general, the intensity of

mouth region activity was most indicative of a genuine smile

expression.

We examined the relative importance of the upper and lower

part of the face in dynamic D and ND smiles made under spon-

taneous and deliberate conditions. Participants were presented withpartial faces that showed either the upper or the lower face. Given

that the D marker is a feature of the upper face, it should play a

significant role in the distinction between D and ND smiles only in

the upper face. Differences in ratings of genuineness and amuse-

ment of D and ND smiles should therefore be absent or at least

attenuated when judges have access solely to the lower face.

Method

Participants

Fifty-one undergraduate students (22 men, 29 women), ages 18

to 34 years ( M 20.57 years, SD 2.84) at Cardiff University

took part individually either for course credit or for a payment

of £3.


The smile stimuli were the same as those used in Experiment 2,

except that only spontaneous D smiles of higher intensity (pro-

nounced) were included. This resulted in a design with four smile

types: (a) 6 spontaneous D smiles, (b) 6 spontaneous ND smiles,

(c) 6 deliberate D smiles, and (d) 6 deliberate ND smiles. Smile

type (D, ND) and condition (spontaneous, deliberate) were treated

as two independent factors. Two partial face versions were created

for each of the 24 expressions, showing either the lower or upper

face with the other half covered by a black mask. Lower face

versions showed the mouth area only, including the nasolabial

furrows. Upper face versions showed the eye area only, including

the cheek bulges. The resulting 48 facial stimuli were displayed as

movie clips in MediaLab (Empirisoft) and shown in random order.

Procedure and Dependent Variables

These were the same as in Experiment 2, except that participants

were told that for each stimulus person only the lower or upper part

of the face would be visible. The dependent variables were iden-

tical to those used in Experiment 2.



The three dependent measures were entered into a MANOVA,

with face (lower, upper), condition (spontaneous, deliberate), and

smile type (D, ND) as within-subjects factors, and sex of partici-

pant (male, female) as a between-subjects factor. The main effect

of sex of participant was not significant, F (3, 47) 2.60, p .05,

p2

.14. A significant main effect was found for face, F (3, 47)

10.65, p .001, p2 .40. This was significant only for ratings of

amusement, F (1, 49) 8.31, p .01, p2

.14. Smiles shown in

the lower face attracted significantly higher amusement ratings

( M 3.53) than those shown in the upper face ( M 3.38). Thisis consistent with the notion that the lower face is more influential

in shaping attributions of happiness and amusement (Bassili, 1979;

Kerstenbaum, 1992; Tremblay et al., 1993). An upward turning

mouth therefore appears to be the strongest determinant of how

much amusement smiles are seen as conveying.

Significant main effects also emerged for condition, F (3, 47)

11.49, p .001, p2

.42, and smile type, F (3, 47) 105.66, p

.001, p2

.87. These two main effects were qualified by a

significant interaction between condition and smile type, F (3,

47) 31.64, p .001, p2

.67. The interaction was significant

for all three dependent variables: spontaneous, F (1, 49) 23.35,

Table 2

Multiple Regression Analyses of Ratings of Genuineness and Amusement of Smiles in Experiments 2, 3, and 4 on Seven Facial

Features (Values Are Standardized Regression Coefficients)

Experiment Condition/RatingDuchenne

marker Asymmetry IrregularityOnsettime

Apextime

Offsettime

Nonpositivefacial action

2 Genuine .17 .39

.08 .10 .42

.02 .32

Amused .29 .21 .12 .13 .44 .08 .42

3 Upper faceGenuine .53 .21 .18 .07 .19 .12 .23Amused .56 .20 .11 .02 .22 .06 .24

Lower faceGenuine .19 .40 .00 .02 .56 .10 .11Amused .37 .25 .06 .03 .46 .08 .23

4 DynamicGenuine .14 .55 .02 .16 .62 .03 .29Amused .34 .19 .08 .10 .41 .04 .37

StaticGenuine .31 .02 .15 .01 .34 .01 .46

Amused .61 .03 .09 .00 .21 .04 .36

p .05. p .01.




p .001, p2

.32; genuine, F (1, 49) 27.40, p .001, p2

.36; and amused, F (1, 49) 89.88, p .001, p2

.65. Analyses

of simple effects showed that D smiles made under both sponta-

neous and deliberate conditions were rated as more genuine—

spontaneous, F (1, 49) 52.46, p .001, p2

.52; deliberate,

F (1, 49) 20.24, p .001, p2

.29 —and amused—

spontaneous, F (1, 49) 200.38, p .001, p

2

.80; deliberate,F (1, 49) 95.78, p .001, p

2 .66—than were ND smiles.

Thus, participants were sensitive to the presence or absence of the D

marker within each condition, although such differences in the ratings

of D and ND smiles were greater in the spontaneous condition than in

the deliberate condition (see Table 1, Experiment 3).

As in Experiment 2, judgments of D smiles varied significantly

between the spontaneous and deliberate conditions. In particular,

spontaneous D smiles attracted higher ratings of genuineness, F (1,

49) 43.19, p .001, p2

.47, and amusement, F (1, 49)

85.56, p .001, p2

.64, than did deliberate D smiles. Repli-

cating the findings of Experiment 2, this supports the notion that

there is just one type of genuine felt smile, namely the spontaneous

D smile.

Elicitation condition did not influence the perceived genuine-

ness of ND smiles, F (1, 49) 0.35, p .05, p2

.01. However,

participants judged deliberate ND smiles to be more amused than

spontaneous ones, F (1, 49) 10.67, p .01, p2 .18. Whereas

D smiles are perceived as reflecting greater amusement when they

are shown spontaneously rather than deliberately, the opposite is

true for ND smiles.

Unexpectedly, these effects were not qualified by the face

variable. The interaction between face and smile type was not

significant, F (3, 47) 1.83, p .05, p2

.10. Thus, the

differences between ratings of D and ND smiles did not vary as a

function of whether the upper or the lower face was shown. This

seems odd given that the principal physical difference between D

and ND smiles is visible only in the upper face. As we will see inthe regression analyses, however, other features contributed to

participants‘ ratings, and these may have enabled them to distin-

guish between smile types simply on the basis of the lower face.

Regression Analyses

Multiple regression analyses showed that the pattern of results

varied depending on whether the lower or upper face was shown

(see Table 2, Experiment 3). As expected, in the upper face

condition only the D marker was a significant and positive pre-

dictor of how genuine and amused ( ps .05) the smile was

perceived to be. However, other features were significant predic-

tors of ratings made in the lower face condition. Here, apexduration ( ps .05) and asymmetry ( ps .05) were associated

with ratings. As in Experiment 2, the longer the apex duration, the

more genuine and amused the smile was perceived to be. In

addition, the less asymmetrical the smile was, the more genuine it

was seen to be. Given that apex duration and asymmetry differed

between the smile types (see above), these features may have

contributed not only to overall ratings of genuineness and amuse-

ment in the lower face, but also to the distinction between D and

ND smiles. Thus, the role played by the D marker in judgments of

the upper face seems to have been taken over by asymmetry and

apex duration when only the lower face was visible.

Experiment 4

Our aim in this study was to examine whether judgments of

smiles would be affected by seeing static images versus dynamic

displays. Several studies have shown that dynamic information

increases the recognition of emotional expressions (Ambadar,

Schooler, & Cohn, 2005; Bassili, 1979; Bould & Morris, 2008;

Bruce & Valentine, 1988; Wehrle, Kaiser, Schmidt, & Scherer,

2000) and influences perceptions of the naturalness and spontane-

ity of expressions (Krumhuber & Kappas, 2005; Sato & Yo-

shikawa, 2004). These benefits of dynamic displays were found to

be due to the motion signal itself rather than additional static

information contained in moving sequences. Ambadar et al. (2005)

and Bould and Morris (2008) showed that “multistatic sequences,”

containing the same number of frames as dynamic images but with

a mask between each frame to prevent apparent motion, were

recognized with lower accuracy than dynamic displays.

We used a similar paradigm in which participants were pre-

sented with either multistatic images or dynamic displays of spon-

taneous and deliberate D and ND smiles. Bearing in mind that the

D smile is defined in terms of its morphology, we expectedperceivers to be able to distinguish between D and ND smiles

regardless of whether the smiles were static or dynamic. However,

the ability to distinguish between spontaneous and deliberate

smiles should be impaired when seeing static displays because

dynamic information concerning the spontaneity and genuineness

of a smile is absent. Participants should therefore distinguish

between spontaneous and posed smiles only when exposed to

dynamic faces, with spontaneous smiles being rated as more gen-

uine and amused.

Method

Participants

Sixty undergraduate students (30 men, 30 women), ages 18 to

32 years ( M 22.35 years, SD 3.46) at Cardiff University took

part individually in this study either for course credit or for a

payment of £2. Half were randomly allocated to the static mode,

the other half to the dynamic mode.


The same four smile types as in Experiment 3 were employed:

(a) 6 spontaneous D smiles, (b) 6 spontaneous ND smiles, (c) 6

deliberate D smiles, and (d) 6 deliberate ND smiles. In the dy-

namic mode condition, these 24 smiles were shown to the partic-

ipants as video clips. In the static mode condition, each smile was

represented by a sequence of five still images extracted from thevideo sequences. Images reflected the time course of the expres-

sion and showed a neutral face (first frames), followed by the smile

halfway through its onset (frame at midpoint from the start of the

smile to its peak), at its apex (frame at peak intensity), halfway

through its offset (frame at midpoint from the decrease of the smile

to its neutral position), and a neutral face (last frames) at the end.

These five images were displayed for the same total duration as the

corresponding clips in the dynamic mode. To prevent any percep-

tion of motion in the static sequences, we separated successive

pairs of static images by a blank screen that lasted 5 frames. The

resulting 24 sequences of static images were shown to all partic-




ipants in the static mode condition. In both conditions (static and

dynamic), stimuli were presented in random order via MediaLab

(Empirisoft).

Procedure and Dependent Variables

The procedure in the dynamic condition was identical to that in

Experiment 2. In the static condition, participants were instructed

as follows: “What you are going to see is a series of still images,

each of which depicts a person expressing a spontaneous or posed

smile. Each picture in the set shows one segment of the smile

episode. The pictures are separated by a blank screen. In total, you

will only see 5 still pictures of each episode. The duration for

which the pictures are displayed will vary.” Further instructions

regarding the nature of spontaneous and deliberate smiles, as well

as the experimental task and procedures for responding, were the

same as in the previous studies. The dependent variables were the

same as those used in Experiments 2 and 3.



A MANOVA with condition (spontaneous, deliberate) and

smile type (D, ND) as within-subjects factors and display mode

(static, dynamic) and sex of participant (male, female) as between-

subjects factors was conducted on the three dependent variables.

The main effect of sex of participant was not significant, F (3,

54) 2.29, p .05, p2

.11. There was a significant main effect

of display mode, F (3, 54) 3.53, p .05, p2

.16. This was

significant only for amusement, F (1, 56) 5.87, p .05, p2

.09. Overall, static displays attracted significantly higher amuse-

ment ratings ( M 3.64) than did dynamic displays ( M 3.36).

Consistent with expectations, there was a significant interaction

between condition and display mode, F (3, 54) 7.43, p .001,p

2 .29. It was significant for all three variables: spontaneous, F (1,

56) 21.41, p .001, p2 .28; genuine, F (1, 56) 15.06, p

.001, p2

.21; and amused, F (1, 56) 14.34, p .001,

p2 .20. Paired samples t tests showed that participants discrim-

inated between spontaneous and deliberate smiles in the dynamic,

but not in the static, mode. As can be seen in Figure 1, spontaneous

smiles were rated as more genuine, t (29) 3.94, p .001, and

amused, t (29) 5.38, p .001, than deliberate smiles. No such

difference emerged for static displays—genuine, t (29) 1.03,

p .05; amused, t (29) 0.22, p .05— indicating that signif-

icant information about the spontaneity of the expression was not

transmitted via static cues. The finding is consistent with previous

research and suggests that dynamic displays convey information rel-

evant to expression perception over and above that contained in static

representations (see Ambadar et al., 2005; Wehrle et al., 2000).There was also evidence that participants were misled by the

static representations. Independent samples t tests showed that

significantly higher ratings of genuineness, t (58) 2.78, p .01,

and amusement, t (58) 3.69, p .001, were given to deliberate

smiles, and that spontaneous smiles were perceived as less genuine

when shown in the static compared with the dynamic mode,

t (58) 1.98, p .05. This shows that static displays resulted in

less accurate judgments of both spontaneous and deliberate smiles

and also to an overattribution of emotion in the case of deliberate

smiles.

The influence of the D marker should not depend on whether a

face is static or dynamic. Indeed, the effect of the presence or

absence of this marker was not moderated by display mode. There

were significant main effects for condition, F (3, 54) 6.35, p

.01, p2

.26, and smile type, F (3, 54) 115.78, p .001, p2

.86. These were qualified by a significant interaction between

condition and smile type, F (3, 54) 17.71, p .001, p2

.50.

The interaction was significant for all three dependent measures:

spontaneous, F (1, 56) 24.44, p .001, p2 .30; genuine, F (1,

56) 34.25, p .001, p2

.38; and amused, F (1, 56) 53.81,

p .001, p2

.49. Analyses of simple effects revealed that both

spontaneous and deliberate D smiles were rated as more genuine—

spontaneous, F (1, 56) 57.94, p .001, p2

.51; deliberate,

F (1, 56) 5.44, p .05, p2

.09—and amused—spontaneous,

F (1, 56) 228.24, p .001, p2

.80; deliberate, F (1, 56)

109.42, p .001, p2 .66—than ND smiles (see Table 1,

Experiment 4), thereby replicating the findings of Experiment 3.Comparing smile types across elicitation condition, spontaneous

D smiles were judged to be significantly more genuine, F (1, 56)

29.71, p .001, p2

.35, and amused, F (1, 56) 62.15, p

.001, p2

.53, than deliberate D smiles were. This is in line with

the two previous studies and shows the critical role played by

condition in shaping the perceived quality of D smiles.

It is interesting that participants’ ratings of ND smiles also

varied as a function of elicitation condition, such that less genu-

Figure 1. Genuineness and amusement ratings of spontaneous and deliberate smiles in the static and dynamic

conditions of Experiment 4. Error bars show standard errors.




ineness, F (1, 56) 3.89, p .05, p2

.06, and amusement, F (1,

56) 7.01, p .05, p2

.11, were attributed to spontaneous than

to deliberate ND smiles. The finding provides further evidence of

opposing effects on judgments of D and ND smiles. Among ND

smiles, those made deliberately appear more genuine and as re-

flecting greater amusement than those made spontaneously.

Regression Analyses

Multiple regression analyses showed that the results varied as a

function of static and dynamic displays (see Table 2, Experiment

4). For dynamic displays, the same three facial features as in

Experiment 2 emerged as significant predictors: apex duration

( ps .05), asymmetry ( ps .01), and nonpositive facial actions

( ps .05). The longer the apex, the more genuine and amused the

smile was judged to be. Similarly, less asymmetry and fewer

nonpositive facial actions were associated with higher ratings of

genuineness and amusement. For static displays, only nonpositive

facial actions ( ps .05) and the D marker ( ps .05) significantly

predicted judgments. Higher ratings of amusement were given to

smiles characterized by fewer nonpositive facial actions and by theD marker. Similarly, fewer nonpositive facial actions were asso-

ciated with increased ratings of smile genuineness.

General Discussion

The aim of this research was to test the value of the D smile as

a spontaneous and genuine sign of enjoyment. It has been argued

that D smiles signal spontaneous, felt emotions that differ from

posed or false smiles with respect to the presence of AU 6. In the

present research, we explored the reliability and validity of the D

smile with respect to both expression and perception. In Experi-

ment 1, we focused on expression and investigated whether people

were able to activate the orbicularis oculi , pars lateralis muscle(AU 6) to produce a voluntary D smile and how frequently they

did so. We examined whether D smiles occur solely or predomi-

nantly under spontaneous conditions, and whether ND smiles

occur solely or predominantly under deliberate conditions. Partic-

ipants either spontaneously smiled in reaction to genuinely amus-

ing stimuli (spontaneous condition) or were instructed to pose a

smile expression (deliberate condition). It is interesting that there

were similar proportions of smiles with and without the D marker,

AU 6, in these two conditions. Thus, senders could produce D

smiles deliberately, and they did so quite often. Furthermore, not

all the observed ND smiles were posed; some occurred in the

spontaneous condition. These findings are in line with increasing

evidence that D smiles and ND smiles can occur under both

spontaneous and deliberate conditions (Schmidt & Cohn, 2001;Schmidt et al., 2006, 2009; Smith et al., 1996) and cast doubt on

claims that D smiles are spontaneous signs of felt enjoyment that

cannot be feigned (Ekman, 1985, 1989, 1993).

Whether a D or ND smile was shown was less a function of the

spontaneity of the expression than of the intensity of the smile. D

smiles were more intense than ND smiles, and when they were

made deliberately, they were even more intense than D smiles

made in the spontaneous condition. This is consistent with obser-

vations that D smiles tend to involve stronger smiling actions than

ND smiles and that they covary with the degree of smile strength

(Ekman & Friesen, 1978; Frank et al., 1993). In a recent study by

Messinger et al. (2008), changes in smile intensity were also found

to be linked to changes in eye constriction (AU 6). That is, the

more intense the smile expression, the higher was the probability

of a D smile. Messinger et al. (2008) consequently suggested

treating AU 6 in D smiles not as a dichotomous signal that

distinguishes D from ND smiles (see Abe, Beetham, & Izard,

2002; Messinger, 2002; Messinger et al., 1999, for similar claims),but rather as an ordinally graded index of smile intensity. An

important source of such association may be muscular synergies

(Messinger et al., 2008). That is, as the zygomaticus major muscle

pulls the lip corners upward, it raises the cheeks toward the eyes.

These synergies provide a basis for explaining the effects of

expression intensity by linking the occurrence of AU 6 directly to

the intensity of the smiling action (AU 12). 4

Self-reports of positive experience varied as a function of both

elicitation condition and smile type. Higher ratings accompanied D

smiles occurring in the spontaneous condition than in the deliber-

ate condition. This supports the notion that only the spontaneous D

smile reflects genuine enjoyment (Ekman et al., 1988, 1990; Frank

et al., 1993). By contrast, in the deliberate condition senders were

able to produce D smiles that did not reflect felt positive affect.Whether made spontaneously or deliberately, however, D smiles

were associated with more positive emotion than ND smiles,

suggesting that this relation holds even when a D smile is being

posed. A possible avenue for future research would be to study the

relation between D smiles and emotional experience under varying

conditions, including negative ones. Whereas Bonanno and col-

leagues (Keltner & Bonanno, 1997; Papa & Bonanno, 2008)

showed that D smiles led to less negative feelings on the part of

individuals talking about their recently deceased spouse or in

response to a negative affect manipulation during a monologue

task, such mitigation of negative affect by D smiles was not found

by Soussignan (2002). Moreover, the content of participants’ talk

in the monologue task (Papa & Bonanno, 2008) and the bereave-ment interview (Keltner & Bonanno, 1997) during which facial

behaviors were measured was not taken into account. An important

step, therefore, would be to conduct a time-based analysis of facial

behavior in order to clarify the extent to which D smiles serve a

self-regulatory function. Preliminary work of this nature has al-

ready been done by Wagner and Lee (1999; see also Lee & Beattie,

1998), who tracked the occurrence of D and ND smiles in relation

to specific events in time. These researchers found considerable D

smiling accompanying negative statements. Further research is

clearly needed to shed more light on the intrapersonal conse-

quences of D smiles.

In Experiments 2–4, we focused on the perception of smiles.

Specifically, we examined how genuine and amused D and ND

smiles were judged to be, and whether people distinguished be-

4 It is worth noting that the neurological claims for different neural

pathways involved in spontaneous (D: AU 6 12) and deliberate (ND: AU

12) smiles are not unequivocal. The neurological literature shows that it is

difficult to provide a precise definition of the neural systems involved in

these two processes (Pizzamiglio, Caltagirone, & Zoccolotti, 1989). In-

deed, Ekman and colleagues concluded that the voluntary–involuntary

dichotomy is too simple (Ekman et al., 1981). Instead, these authors

suggested that there are several types of voluntary and involuntary expres-

sions, each likely to vary with respect to the underlying neural pathways

(Ekman, 1984).




tween these two smile types when they were made under sponta-

neous and deliberate conditions. In each study, we also investi-

gated the predictive value of the D marker alongside other smile

attributes such as asymmetry; irregularity; onset, apex, and offset

durations; and nonpositive facial actions. If the D marker is indeed

the most diagnostic symptom of a felt smile, we expected its

capacity to predict perceivers’ ratings of the smiles to be consistentand at least as great as the predictive value of the other smile

attributes.

Participants generally rated spontaneous and deliberate smiles

differently. In all three studies, the spontaneous D smile was rated

as most genuine and amused, consistent with the notion that this

type of smile is perceived as expressing felt positive emotion

(Frank et al., 1993; Gosselin, Beaupre, & Boissonneault, 2002;

Gosselin, Perron, et al., 2002). In Experiment 2, perceivers also

distinguished between spontaneous D smiles that varied in inten-

sity. D smiles of higher intensity were judged to reflect greater

subjective enjoyment than D smiles of lower intensity. This shows

that the intensity of the expression made by a sender significantly

affected how spontaneous his or her D smiles were perceived to be

and extends previous research on the effects of expression inten-sity (e.g., Bolzani Dinehart et al., 2005; Hess et al., 1997; Mess-

inger et al., 2008).

In Experiment 3, perceivers were shown either the upper or the

lower face. Contrary to expectations, similar ratings were made

when seeing the upper or lower face, showing that judges were

able to use cues other than the D marker itself to distinguish

between D and ND smiles. In Experiment 4, perceivers saw static

or dynamic versions of the smiles, and this had a significant impact

on judges’ ratings. When smiles were presented in their dynamic

form, spontaneous smiles were judged as more genuine and

amused than deliberate smiles. However, this difference did not

emerge for static displays. This is consistent with past research on

dynamic displays (Ambadar et al., 2005; Wehrle et al., 2000) andshows that dynamic information contains important cues concern-

ing the spontaneity of the expression.

In comparing the utility of several physical attributes of smiles

in predicting how smiles were judged, we found that asymmetry of

expression and apex duration were consistent predictors across the

three studies. The less asymmetric the smile was and the longer its

apex duration, the more genuine and amused it was judged to be.

The presence of nonpositive facial actions also significantly pre-

dicted judgments, with smiles being rated as more genuine and

amused when they had fewer nonpositive facial actions, such as

frowning and lip pressing. These findings extend previous research

(Ambadar et al., 2009; Gosselin, Beaupre, & Boissonneault, 2002;

Gosselin, Perron, et al., 2002; Krumhuber & Kappas, 2005) and

suggest that all three variables contribute to how smile expressionsare evaluated. It is interesting that the predictive utility of the D

marker was rather limited. It only significantly predicted ratings

when judges saw the upper face or when they viewed static rather

than dynamic displays. Furthermore, in the case of static displays,

the D marker predicted only how amused (but not how genuine)

the smile was judged to be. These results call into question the

received wisdom that the D marker is the most reliable index of

felt positive emotion (Frank & Ekman, 1993). Our findings point

to a different conclusion, namely that the D marker is one among

several attributes that lead judges to regard smiles as genuine and

as reflecting amusement. In the present research, the D marker was

not the most diagnostic attribute, nor was it a consistent cue for

rating smiles as expressing spontaneous amusement.

Much of our current understanding of facial expressions of

emotion derives from research using static facial images (Russell,

Bachorowski, & Fernandez-Dols, 2003). A distinction is often

drawn between “spontaneous” and “deliberate” smiles on the basis

of the presence or absence of the D marker. Clearly, this morpho-logical marker is discernible in static displays and, as the present

research shows, it has reliable effects on how smiles are judged on

the basis of static images. In everyday life, however, judgments of

the genuineness of smiles are made on the basis of dynamic

expressions, and the evidence from the present research is that the

D marker is a less important cue when dynamic information is

available. Future research should focus on dynamic displays and

consider a broader range of behavioral cues than the D marker.

A feature of the present work that might be regarded as a

limitation stems from the way in which we equated smile intensity

across conditions in the three judgment studies, with D and ND

smiles being of comparable intensity in both the spontaneous and

deliberate conditions. There is no doubt that expression intensity

influences the perceived intensity of the associated emotion (seeBolzani Dinehart et al., 2005; Hess et al., 1997; Messinger et al.,

2008). However, in the present research, we wanted to rule out

differences in smile intensity as a possible explanation for differ-

ential responses to smiles in the spontaneous and deliberate con-

ditions. We therefore kept this variable constant across conditions

and considered the effects of expression intensity separately in

Experiment 2, where we examined the perception of D smiles that

differed in intensity within the spontaneous condition. Future

research could include a broader range of variation in smile inten-

sity and examine whether the influence of other physical attributes

such as the ones studied in the current research is moderated by

smile intensity.

In conclusion, we have shown that D smiles occurred as bothfelt and posed expressions, and that the presence or absence of the

D marker was not the only basis on which those who judged smiles

made ratings of genuineness and amusement. The role of the D

marker, AU 6, therefore needs to be reconsidered. The D smile is

operationalized as the combination of AUs 6 and 12. It is clear that

D smiles can and do occur when the individual experiences gen-

uine amusement. However, it is not the case that all smiles involv-

ing the D marker reflect genuine amusement. D smiles also occur

when the individual poses amusement and are even shown under

negative emotional circumstances. The usefulness of facial muscle

units such as AUs 6 and 12 in identifying whether a smile ex-

presses enjoyment is therefore thrown into doubt. The evidence

from the present research is that the D marker by itself is not a

reliable basis for inferring whether a smile is spontaneous, genu-ine, or reflective of subjective amusement.

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Received December 12, 2007

Revision received October 1, 2009

Accepted October 1, 2009


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