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Something to smile about: The interrelationship between attractiveness and emotional expression Jessika Golle a

a b

, Fred W. Mast

a b

& Janek S. Lobmaier

a b

Department of Psychology , University of Bern , Bern , Switzerland

b

Centre for Cognition, Learning, and Memory , University of Bern , Bern , Switzerland Published online: 22 Jul 2013.

To cite this article: Cognition & Emotion (2013): Something to smile about: The interrelationship between attractiveness and emotional expression, Cognition & Emotion, DOI: 10.1080/02699931.2013.817383 To link to this article: http://dx.doi.org/10.1080/02699931.2013.817383

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COGNITION AND EMOTION, 2013 http://dx.doi.org/10.1080/02699931.2013.817383

Something to smile about: The interrelationship between attractiveness and emotional expression Jessika Golle1,2, Fred W. Mast1,2, and Janek S. Lobmaier1,2 1

Department of Psychology, University of Bern, Bern, Switzerland Centre for Cognition, Learning, and Memory, University of Bern, Bern, Switzerland

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Previous studies have suggested a link between the processing of the emotional expression of a face and how attractive it appears. In two experiments we investigated the interrelationship between attractiveness and happiness. In Experiment 1 we presented morphed faces varying in attractiveness and happiness and asked participants to choose the more attractive of two simultaneously presented faces. In the second experiment we used the same stimuli as in Experiment 1 and asked participants to choose the happier face. The results of Experiment 1 revealed that the evaluation of attractiveness is strongly influenced by the intensity of a smile expressed on a face: A happy facial expression could even compensate for relative unattractiveness. Conversely, the findings of Experiment 2 showed that facial attractiveness also influences the evaluation of happiness: It was easier to choose the happier of two faces if the happier face was also more attractive. We discuss the interrelationship of happiness and attractiveness with regard to evolutionary relevance of positive affective status and rewarding effects. Keywords: Attractiveness; Emotional expression; Happiness; Attractiveness judgement; Happiness judgement.

Faces play an integral role in human social interactions. A face contains intricate information on the basis of which a familiar person can be distinguished from a stranger, a woman from a man, and older people can be distinguished from young people. From a face we can also judge whether the person is attractive, or what mood he or she is in. Such first impressions may facilitate communication and co-operation. Ultimately, whether we like a particular face or not will also help to determine who we chose as a mate: Several

studies have emphasised the importance of facial attractiveness for mate preferences and mate ¨ hman, 2000; choice (e.g., Lang, Davis, & O Peters, Simmons, & Rhodes, 2009; Rhodes, 2006; Symons, 1980; Thornhill & Gangestad, 1999). An important factor that influences the perception of facial attractiveness is emotional expression (e.g., Bell, 1978; Cunningham, 1986; Cunningham, Barbee, & Pike, 1990; Harker & Keltner, 2001; Krumhuber, Manstead, & Kappas,

Correspondence should be addressed to: Jessika Golle, University of Bern, Department of Psychology, Fabrikstrasse 8, CH3012 Bern, Switzerland. E-mail: [email protected] JG was supported by a grant from the Pro*Doc program of the Swiss National Science Foundation awarded to FWM (PDFMP1_127238). JSL was supported by the Swiss National Science Foundation (grant number PZ00P1_121622/1). # 2013 Taylor & Francis

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2007; Mehu, Little, & Dunbar, 2007; Mueser, Grau, Sussman, & Rosen, 1984; Otta, Abrosio, & Hoshino, 1996; Tracy & Beall, 2011). Mueser and colleagues investigated how different facial expressions influence apparent attractiveness (Mueser et al., 1984). Faces of the same identity were presented with a happy, neutral, and sad expression and participants assessed the attractiveness of each face on a 10-point Likert scale. The results revealed a significant decrease in attractiveness assessments for sad compared to happy and neutral faces but no difference in the perceived attractiveness between neutral and happy faces. Others have specifically focused on happy expressions and investigated the influence of a smile on attractiveness judgements (Cunningham, 1986; Cunningham et al., 1990). They measured smile width and height in male and female faces and asked participants to rate the attractiveness of these faces. The results revealed a positive correlation between smile width and attractiveness. Similarly, Harker and Keltner (2001) found a positive correlation between the intensity of natural smiles and ratings on physical attractiveness. Otta and colleagues (1996) examined the effects of different types of smiling (closed, upper, and broad smile) on perceived attractiveness. They presented smiling faces as well as faces with a neutral expression and asked participants to evaluate these faces according to various aspects (e.g., attractiveness, happiness). The results revealed that faces were rated more attractive when smiling compared to when their expression was neutral. The form of smile did not affect the attractiveness scores. Mehu and colleagues (2007) studied whether ratings of attractiveness, generosity, and trustworthiness depend on the genuineness of a smile (i.e., Duchenne and nonDuchenne smiles). In line with the results of Otta et al. (1996), Mehu et al. (2007) found higher attractiveness ratings for smiling faces compared to faces with a neutral expression. However, whether the smile was genuine or not (Duchenne vs. non-Duchenne) had no influence on the attractiveness judgements.

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These findings are corroborated by a brain imaging study suggesting that the processing of happy facial expressions and attractiveness share some underlying neural mechanisms. O’Doherty and colleagues (2003) investigated the brain structures that were activated by viewing attractive faces showing either a neutral or mildly happy expression. They found that when the faces were comparably attractive a smile compared to a neutral facial expression induced enhanced activity in the brain’s reward system (medial orbitofrontal cortex). The neuronal processing of attractiveness seems to be influenced by facial expression. In the present study we went beyond previous research in that we investigated how strongly happiness influences the evaluation of attractiveness and whether facial attractiveness influences the interpretation of happiness. In contrast to previous experiments we studied the influence of a happy facial expression on attractiveness judgements by directly investigating whether a less attractive face with a happy facial expression is preferred to an actually more attractive face with a less happy facial expression (Experiment 1). We also examined the influence in the reverse direction, that is the influence of facial attractiveness on happiness judgements (Experiment 2). We employed a two alternative forced choice (2AFC) paradigm in which participants had to choose one of two simultaneously presented stimuli. Such a paradigm allows for testing judgements on stimulus pairs that differ only very subtly (see, e.g., Sprengelmeyer et al., 2009). We were interested in the perception of subtle attractiveness and happiness differences and therefore used face pairs as stimuli that systematically and independently varied in happiness and attractiveness while face identity was kept constant. In Experiment 1 the task was to choose the more attractive face of a pair. According to earlier findings, we expected a smile to positively influence the attractiveness judgements, especially for female faces, since female attractiveness has been found to benefit more from a smiling expression than male attractiveness (e.g., Harker & Keltner, 2001; Krumhuber et al., 2007; Tracy & Beall, 2011; but see Cunningham, 1986; Cunningham

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et al., 1990; Mehu et al., 2007; Otta et al., 1996). However, no study has yet specifically investigated how strongly a happy expression may influence attractiveness judgements. It has been suggested that attractiveness supports the identification of good mates (Thornhill & Gangestad, 1999) because attractiveness may be associated with good health (especially for Rhodes, 2006; Weeden & Sabini, 2005). We therefore assume that the more attractive but neutral looking face will be perceived as more attractive when compared to the less attractive but smiling face, since trait-like attractiveness should prevail over the more temporary facial expression. By presenting a less attractive/more smiling face together with a more attractive/less smiling face, we determined the magnitude of the influence of a happy facial expression on attractiveness judgements. In Experiment 2 we presented the exact same stimulus pairs as in Experiment 1, but asked participants to choose the happier face. This enabled us to examine the interrelation between the perception of a positive expression and attractiveness. So far, there is no literature reporting an influence of facial attractiveness on the perception or evaluation of emotional expressions. We could therefore expect two possible outcomes: (1) Faces that were manipulated to look happier would be chosen to be happier independent of how attractive they were; and (2) Attractiveness would either facilitate or impair happiness judgements. No interaction between attractiveness and happiness would suggest independence of the evaluation of these attributes. Conversely, a modulation of the perception of emotional expression by facial attractiveness would suggest that*at least partially*a common mechanism underlies the processing of facial attractiveness and happiness (cf. O’Doherty et al., 2003).

In summary, the main aims of this study were: (1) To establish how strongly a happy facial expression influences attractiveness judgements (e.g., whether happiness can compensate for relative unattractiveness); and (2) To examine whether attractiveness influences happiness judgements. Understanding the interaction between a happy expression and attractiveness is important, since both facial attributes are likely to influence the rewarding value of a face, whereby attractiveness is a more trait-like aspect of a face and the emotional expression is transient.

GENERAL METHOD Overview In each experiment we presented pairs of adult faces of the same identity but with manipulated attractiveness and/or emotional expression. We used a 2AFC paradigm and participants were asked to choose the more attractive (Experiment 1) or the happier face (Experiment 2).

Stimuli The stimuli were created in PsychoMorph (Burt & Perrett, 1995; Tiddeman, Burt, & Perrett, 2001). Adult faces varying in attractiveness were created in three consecutive steps. First, for each sex, 10 very attractive and 10 very unattractive face images with a neutral facial expression1 were averaged to create sex-specific attractive and unattractive prototypes (Figure 1a). As a result of the averaging process, each of the prototypes (attractive and unattractive) emphasised the similarities and reduced the differences of facial attributes between the individual faces included in the prototype (see Tiddeman et al., 2001, for more information). In a second step, 10 stimulus

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Stimuli were taken from various databases: Cal/Pal Database (Minear & Park, 2004); FACES Database (Ebner, Riediger, & Lindenberger, 2010); Gomi (Gomi, 1994); RAFD Database (Langner et al., 2010); WSEFEP (Olszanowski, Pochwatko, Kuklin´ski, S´ cibor-Rylski, & Ohme, 2008); NimStim (Tottenham et al., 2009); and Karolinska Database (Lundqvist, Flykt, & ¨ hman, 1998). Additional face stimuli were provided by David Perrett and Janek Lobmaier from their personal stimulus O collections. One hundred fifty-four front-view Caucasian adult faces showing direct gaze and either a neutral or happy facial expression were selected and were rated for attractiveness on a 7-point rating scale (from 1  Not attractive to 7  Very attractive) by 10 participants (five male).

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Figure 1. (a) Sex-specific prototypes of Experiment 1 and 2: unattractive/neutral (left), unattractive/happy (right). (b) Sex-specific prototypes of Experiments 1 and 2: attractive/neutral (left), attractive/happy (right). (c) Upper panel: Example of a transformation continuum (unattractive/happy to attractive/neutral). Lower panel: Transformations of the presented identity, and face pairs presenting shape differences in happiness and attractiveness of 25%, 50%, 75%, and 100%. Each left face of one pair is the happier and less attractive face.

identities (five male) were created by averaging four different identities of moderate attractiveness, to ensure anonymity. In a last step, the unattractive and attractive prototypes were taken as the two endpoints of a continuum between which the 10 stimuli were shape-transformed in nine steps (50%, 37.5%, 25%, 12.5%, 0%, 12.5%, 25%, 37.5%, 50%) separately for male and female stimuli (see Tiddeman et al., 2001, for more details). Transformation step 0% (original image) was excluded and the remaining images were paired in such a way that the respective differences between the stimuli were 100%, 75%, 50% and 25% of the shape-specific information of attractiveness. These stimuli were used in the pre-study. The stimuli used in Experiments 1 and 2 were manipulated in both attractiveness and happiness

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and were created as follows. First, we averaged 10 male and 10 female smiling faces of medium attractiveness to produce prototypes with happy facial expressions. Then, each of our sex-specific attractive and unattractive prototypes (reported above) was shape-transformed in one direction only (starting from the original image) towards the sexmatched smiling prototype (50%). The resulting faces served as happy/attractive and happy/unattractive prototypes in addition to the neutral/attractive and neutral/unattractive prototypes reported above (Figure 1a and 1b). These unattractive/neutral, attractive/neutral, unattractive/happy and attractive/happy prototypes were then used to create stimuli varying in attractiveness and happiness. The same 10 stimulus identities (five male) described above were shape-transformed along the two

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continuums of attractiveness and happiness. The poles of the first continuum were the unattractive/ neutral and attractive/happy prototypes; the unattractive/happy and attractive/neutral prototypes were used as the poles of the second transformation continuum. Within each of these respective transformation continuums the shape information of each stimulus identity was manipulated in nine steps, which resulted in four pairs of stimuli differing in 100%, 75%, 50% and 25% of their shape. These transformation steps reflected the systematic shape differences in attractiveness and happiness (Figure 1c). All stimuli had a size of 1290940 mm and a resolution of 72 dpi. Participants were seated 60 cm in front of a 23ƒ computer screen with a resolution of 19201200 pixels; thus, the stimuli subtended a visual angle of 11.3289.038.

was either the proportion of faces correctly judged to be more attractive (pre-study and Experiment 1) or happier (Experiment 2). The HuynhFeldt epsilon correction for heterogeneity of covariances (Huynh & Feldt, 1976) was used if sphericity could not be assumed. For post hoc pairwise comparisons we used the Bonferroni correction.

PRE-STUDY: MANIPULATION OF FACIAL ATTRACTIVENESS In the pre-study we used morphed faces with a neutral expression varying in shape-related attractiveness. Our aim was to show that the more attractive face could indeed be detected, thus confirming that our attractiveness manipulation for male and female faces was successful.

Participants All volunteers were students of the University of Bern. All of them gave written informed consent and received either course credit or a snack in return for their participation. The research was approved by the ethics committee of the Faculty of Human Sciences of the University of Bern and conformed with the ‘‘Ethical Principles of Psychologists and Code of Conduct’’ of the American Psychological Association (2002).

Procedure Each trial started with a fixation cross. After 1,000 ms the fixation cross was replaced by a face pair that differed either only in attractiveness (prestudy) or in attractiveness and happiness (Experiments 1 and 2). The face pair was presented until the participants chose the more attractive or happier face by pressing either the ‘‘F’’ or ‘‘J’’ key on a keyboard (‘‘F’’ if the left face was more attractive or happier and ‘‘J’’ if the right face was more attractive or happier) with their respective index fingers. Each face in one pair was presented once on the left and once on the right side.

Data analysis We calculated repeated-measures analyses of variance (ANOVAs) and our dependent variable

Method Sixty-eight (34 female, 34 male) volunteers ranging in age between 19 and 46 (Mage 24.6 years, SD 4.2) participated in this experiment. Their task was to choose the more attractive of two simultaneously presented faces of the same identity. The total number of trials was 80, 2 (stimulus sex)5 (identities) 4 (pair difference) 2 (lateralisation on the screen). The transformation condition was the same for all stimuli: unattractive/neutral to attractive/neutral. We calculated an ANOVA with Pair Difference (100%, 75%, 50%, 25%) and Stimulus Sex (male, female) as repeated-measures factors, and Participant Sex (male, female) as between-subject factor. The dependent variable was the proportion of faces correctly judged as more attractive. Responses were coded as correct if the more attractive face was chosen (i.e., the face that was assimilated to the attractive prototype).

Results and discussion There was a main effect of Pair Difference, F(2.6, 171.75) 30.81, MSE0.70, pB.001, g2p ¼ :32, and a main effect of Stimulus Sex, F(1, 66)  35.74, MSE0.11, pB.001, g2p ¼ :35. The interaction between these factors also reached COGNITION AND EMOTION, 2013

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statistical significance, F(3, 198) 11.16, MSE 0.20, pB.001, g2p ¼ :15. Post hoc pairwise comparisons revealed that only for female faces did the mean proportion of correctly chosen faces differ significantly between the levels of pair difference. There was no significant main effect or interaction with Participant Sex, all ps].322. None of the calculated 95% confidence intervals for the mean values of the interaction included the value 0.5, indicating that all judgements were above chance level. On average, the face that was manipulated to be more attractive was judged as the more attractive face of a pair. However, the results indicated that the attractiveness manipulation of male faces is not comparable to the manipulation of female faces. Therefore, we separately analysed male and female faces in the following experiments.

EXPERIMENT 1: CHOOSING THE MORE ATTRACTIVE FACE WHEN SIMULTANEOUSLY MANIPULATING ATTRACTIVENESS AND HAPPINESS In this experiment we used morphed faces varying in shape-related attractiveness and happiness. The aim was to investigate the influence of the intensity of a smile on attractiveness judgements.

Method Sixty-eight (34 female, 34 male) volunteers ranging in age between 19 and 46 (Mage 24.6 years, SD 4.3) participated in this experiment. Their task was to choose the more attractive of two simultaneously presented faces. The total number of trials was 160, 2 (transformation condition: unattractive/neutral to attractive/happy; unattractive/happy to attractive/neutral) 2 (stimulus sex)5 (identities) 4 (pair difference) 2 (lateralisation on the screen). We calculated an ANOVA with Pair Difference (100%, 75%, 50%, 25%) and Transformation Condition (unattractive/neutral to attractive/ happy, unattractive/happy to attractive/neutral) as repeated-measures factors, and Participant Sex

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(male, female) as between-subject factor, separately for male and female faces. The dependent variable was the proportion of faces correctly judged as more attractive. Responses were coded as correct if the more attractive face was chosen (i.e., the face that was assimilated to the attractive prototypes: attractive/happy, attractive/neutral).

Results and discussion Female faces. The ANOVA for female faces revealed a significant main effect of Transformation Condition, F(1, 66) 80.10, MSE 0.20, pB.001, g2p ¼ :55, reflecting that it was easier to choose the more attractive face if the faces were transformed between the poles unattractive/neutral and attractive/happy compared to faces which were transformed between unattractive/happy and attractive/neutral. The effect of Pair Difference was also significant, F(2.8, 182.6) 7.48, MSE 0.02, pB.001, g2p ¼ :10, as was the interaction between the factors Transformation Pole and Pair Difference, F(2.7, 178.4) 25.22, MSE 0.02, pB.001, g2p ¼ :28. Post hoc comparisons showed that within the transformation condition unattractive/neutral to attractive/happy there was a significant increase in the mean proportion of correctly chosen faces between the pair difference of 25% and all other pair differences. In the other transformation condition there was no significant increase or decrease, and the 95% confidence intervals for the mean proportions of correctly chosen faces of all pair differences included the value 0.5. Figure 2 illustrates all effects described above. There was no significant main effect or interaction with Participant Sex, all ps ].157. Male faces. For male faces the ANOVA also revealed a main effect of Transformation Condition, F(1, 66) 208.69, MSE0.13, pB.001, g2p ¼ :76, showing that it was easier to choose the more attractive face if faces were transformed between the poles unattractive/neutral to attractive/happy compared to a transformation between the poles unattractive/happy and unattractive/ neutral. The effect of Pair Difference, F(2.6, 169) 3.94, MSE 0.02, p.013, g2p ¼ :06,

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Figure 2. Results for the attractiveness-discrimination task as a function of pair difference (shape differences in happiness and attractiveness of 25%, 50%, 75%, and 100%) and transformation condition (unattractive/happy to attractive/neutral, unattractive/neutral to attractive/happy), separately for male and female faces. Error bars reflect the 95% confidence intervals for the mean proportions of correctly judged faces.

and the interaction between the factors Transformation Condition and Pair Difference were also significant, F(2.8, 182.4) 30.43, MSE 0.02, pB.001, g2p ¼ :32. Post hoc pairwise comparisons revealed that the mean proportion of faces correctly judged as more attractive significantly increased from pair difference of 25% compared to all other pair differences within the transformation continuum unattractive/neutral to attractive/ happy. In contrast to female faces, we found a significant difference in the mean proportion of correctly chosen faces between pair differences 25% and 75% within the transformation continuum unattractive/happy to attractive/neutral continuum. There was no main effect of Participant Sex, p.899. However, the interaction between Pair Difference and Participant Sex reached statistical significance, F(2.6, 169)  2.90, MSE 0.02, p.045, g2p ¼ :04. This interaction reflects the fact that male participants more frequently chose the more attractive face in face pairs that differed by 100% compared to 25% and 75%. For female participants there was no such an effect. No other interactions with Participant Sex were significant, all ps ].431. None of the 95% confidence intervals for the mean proportions of correctly chosen faces of all pair differences included the value 0.5 (Figure 2).

For both sexes we observed a significant Transformation PolePair Difference interaction. We found that the bigger the shape difference, the higher was the mean proportion of correctly chosen faces, but only for faces that were manipulated between the poles unattractive/ neutral and attractive/happy. For faces that were transformed within the continuum unattractive/ happy to attractive/neutral it was much more difficult to judge the more attractive face, especially for female faces. For male faces we observed a significant decrease in the mean proportions of correctly chosen faces over all pair differences. This means that the happier face was on average judged as the more attractive face, independent of the manipulated attractiveness of the face. These results suggest that a happy expression can compensate for relative unattractiveness.

EXPERIMENT 2: CHOOSING THE HAPPIER FACE WHEN SIMULTANEOUSLY MANIPULATING HAPPINESS AND ATTRACTIVENESS In this experiment we used the same stimuli as in Experiment 1 but in contrast to the previous experiment we asked our participants to choose COGNITION AND EMOTION, 2013

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the happier face. Our aim was to investigate the influence of facial attractiveness on happiness judgements.

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Method Fifty-eight (29 female, 29 male) volunteers ranging in age between 19 and 48 (Mage 24.6 years, SD 4.6) participated in this experiment. The total number of trials was 160, 2 (transformation condition: unattractive/neutral to attractive/happy and unattractive/happy to attractive/neutral)2 (stimulus sex)5 (identities)4 (pair difference)2 (lateralisation on the screen). The stimuli and the statistical analysis were thus the same as in the previous experiment, except that the dependent variable was the proportion of faces correctly judged as happier. Responses were coded as correct if the happier face was chosen (i.e., the face that was assimilated to the happy prototypes: attractive/happy, unattractive/happy).

Results and discussion Female faces. For female faces there was a significant main effect of Transformation Condition, F(1, 56) 127.24, MSE0.03, pB.001, g2p ¼ :69, explained by the higher mean proportion of correct answers in the transformation pole unattractive/neutral to attractive/happy compared

to faces that were transformed between the poles unattractive/happy to attractive/neutral. The effect of Pair Difference was also significant, F(2.6, 144.6) 67.82, MSE0.01, pB.001, g2p ¼ :55, as well as the two-way interaction between Transformation Condition and Pair Difference, F(2.7, 151.1) 3.45, MSE0.01, p.022, g2p ¼ :06. Post hoc pairwise comparisons did not reveal systematic differences in the mean proportions of correct answers dependent on transformation condition and pair difference. All described effects are visualised in Figure 3. There was no significant main effect or interaction with Participant Sex, all ps].052. Male faces. Comparable with the results for female faces, the ANOVA for male faces revealed a significant main effect of Transformation Condition, F(1, 56) 40.47, MSE 0.02, pB.001, g2p ¼ :42, signifying that the mean proportion of correctly chosen faces was higher for faces that were transformed between the poles unattractive/ neutral to attractive/happy compared to faces that were morphed between unattractive/happy and attractive/neutral (Figure 3). There was also a significant main effect of Pair Difference, F(2.3, 128.4) 68.48, MSE0.80, pB.001, g2p ¼ :55. Post hoc comparisons showed that the mean proportions of faces correctly judged as happier differed significantly between the pair difference

Figure 3. Results for the happiness-discrimination task as a function of pair difference (shape differences in happiness and attractiveness of 25%, 50%, 75%, and 100%) and transformation condition (unattractive/happy to attractive/neutral, unattractive/neutral to attractive/ happy), separately for male and female faces. Error bars reflect the 95% confidence intervals for the mean proportions of correctly judged faces.

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of 25% and all other pair differences. The interaction between Pair Difference and Transformation Condition did not reach statistical significance, F(2.4, 136.8) 0.92, MSE 0.01. Furthermore, there was no significant main effect or interaction with Participant Sex, all ps ].352. None of the calculated 95% confidence intervals for the mean values of the main effects or interaction included the value 0.5, indicating that all judgements were above chance level. On average, the face that was manipulated to be happier was judged as being happier. According to the significant main effect of transformation condition, the judgement of happiness is influenced by the manipulation of attractiveness for both male and female faces. It was easier to choose the happier face if it was also more attractive. Interestingly, the mean proportion correct between the two transformation conditions differed more strongly for female compared to male faces (see Figure 3). The differences were caused by the happiness decisions in the transformation condition unattractive/happy to attractive/neutral. To test this for significance we averaged the mean proportion correct across all shape differences and compared them between female and male face. We calculated two paired-sample t-tests: one for the transformation condition unattractive/neutral to attractive/happy, t(57)  0.25, p.801, and one for the transformation condition unattractive/ happy to attractive/neutral, t(57)  4.62, pB .001. Less attractive and smiling female faces compared to male faces were less likely to be chosen as looking happier.

SUMMARY AND CONCLUDING DISCUSSION The main aims of this study were to investigate: (1) How strongly a happy facial expression influences attractive judgements (e.g., whether happiness can compensate for relative unattractiveness); and (2) Whether attractiveness influences happiness judgements. Our results revealed an interrelationship between facial attractiveness and emotional expression. Less attractive but

happy faces were judged as equally or even more attractive than their attractive but less smiling counterparts. Interestingly, we also found an effect in the reverse order; the judgement of the expression of a face was affected by its attractiveness. We manipulated faces in terms of attractiveness and happiness using computer graphics software. This enabled us to systematically vary both shape-related attractiveness and happiness while keeping all other facial attributes constant. Participants saw face pairs of the same identity that differed only in attractiveness and expressed happiness and were asked to choose the more attractive (Experiment 1) or the happier face (Experiment 2). We found that the intensity of a smile influenced the judgement of attractiveness for both male and female faces. In line with previous findings (Mehu et al., 2007; Otta et al., 1996) faces were judged as being more attractive when they were smiling. Interestingly, we found that faces that were manipulated to be less attractive but smiling were preferred to faces that were manipulated to be more attractive but less smiling. Importantly, we kept the face identity constant in each stimulus pair, therefore the effects reported here must be the result of our stimulus manipulation (attractiveness/happiness transformation). Thus, our results suggest that smiling can compensate for relative unattractiveness. There are several explanations that could possibly account for this result. First, the finding may be caused by the rewarding value of happy faces. O’Doherty and colleagues (2003) reported that the activity in the brain’s reward system when viewing attractive faces was modulated by expressed happiness of the face. This became evident in enhanced activity in medial orbitofrontal cortex in response to happy attractive compared to neutral attractive faces. Second, the emotional expression might influence the emotional state of the observer, and thus may modulate the attraction to the person (cf. Bell, 1978; Cunningham et al., 1990; Gouaux, 1971; Gouaux, Lamberth, & Friedrich, 1972; Mueser et al., 1984). A positive emotional expression may thus increase the emotional wellCOGNITION AND EMOTION, 2013

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being of the observer, and as a consequence his or her attraction to the face will be increased. Third, a smile might be a cue to better health and thus to genetic benefits than a neutral expression. For example, higher levels of positive affect are associated with a lower incidence of a stroke (Ostir, Markides, Peek, & Goodwin, 2001) and changes in affective states are related to changes in cardiovascular function (Lovallo, 2004; see Barak, 2006; Dockray & Steptoe, 2010, for reviews). Therefore, a positive facial expression may*either consciously or unconsciously*lead to the attribution of a better health status. This explanation, while speculative in nature, could explain our findings according to which the judgement of facial attractiveness is not only dependent on the shape cues to attractiveness but also on the facial expression. Following this line of argumentation, a face expressing happiness will signal good health and thus be regarded as being more attractive. Interestingly, we found that a smile affected the perceived attractiveness of male and female faces in different ways. While smiling enhanced attractiveness for both sexes, male faces benefited more from a smile. This result contradicts the findings of other studies (Harker & Keltner, 2001; Krumhuber et al., 2007; Tracy & Beall, 2011), which reported larger attractiveness benefits for female faces. According to Becker, Kenrick, Neuberg, Blackwell, and Smith (2007) happy facial expressions are associated with femininity and angry expressions with masculinity. Thus, we may have expected reduced attractiveness for smiling men since masculinity might be preferred in male faces. However, Perrett et al. (1998) found that feminised faces were assessed as being more attractive than masculinised faces, independent of the sex of the face. If a happy facial expression increases femininity (Becker et al., 2007) and femininity leads to higher attractiveness (Perrett et al., 1998) a smile is expected to enhance the attractiveness of a face. Ascertaining the reason why such an attractiveness enhancement is stronger for male rather than for female faces will have to be the aim of future research.

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A smile influenced the perception of attractiveness for both sexes, although a happy expression had a more powerful influence on attractiveness judgements of male faces. Participants preferred the more smiling faces although the task was to choose the more attractive face of a pair. It would have been interesting to see whether genuine smiles (i.e., Duchenne smiles) generally have a more powerful impact on attractiveness than non-genuine smiles, because interacting with a genuinely positive person might be more pleasing. Unfortunately, we could not investigate whether the genuineness of the smile had an effect on the attractiveness judgements in the present study as our stimulus material did not systematically differ in terms of Duchenne and nonDuchenne smiles, owing to the technique of stimulus creation used. The results presented in this study not only suggest that the emotional expression affects the perception of attractiveness but also provide first evidence for a mutual dependency between the processing of attractiveness and emotional expressions. The results of Experiment 2 demonstrate that participants were more accurate in choosing the happier face when this face was more attractive. Previous studies have found that various facial attributes (e.g., gender, eye gaze, identity) influence the perception of emotional expression (Atkinson, Tipples, Burt, & Young, 2005; Conway, DeBruine, & Jones, 2006; Fox & Barton, 2006; Schweinberger & Soukup, 1998). We identified attractiveness as a further facial attribute that can modulate the interpretation of facial expressions: happiness was more easily detected in attractive faces. In a recent study, Kloth, Altmann, and Schweinberger (2011) found that facial attractiveness enhanced discrimination of eye gaze direction. Further, attractiveness seems to influence the perception of personality traits (Lorenzo, Biesanz, & Human, 2010). Lorenzo and colleagues found that the more attractive a target person was, the more accurately her/his personality traits were assessed. Taking these findings together, it could be argued that subjects pay more attention to attractive than to less attractive people (Langlois et al., 2000;

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Maner et al., 2003) and thus are more sensitive towards them. We found a larger influence of attractiveness on happiness detection for female compared to male faces. This finding is possibly caused by the attractiveness differences within our stimuli. Attractiveness differences were more pronounced in the female compared to male stimuli (see limitation below). If attractiveness modulates the attention towards people and as a consequence enhances the sensitivity towards facial attributes, the effect of attractiveness should be more pronounced in faces that show more attractiveness variations. This is what we found in our data. The findings of both experiments suggest that facial attractiveness and happiness cannot be processed independently of each other. It is therefore likely that attractiveness and happiness share at least some common processing mechanisms. Such an assumption is in line with the results of O’Doherty and colleagues (2003), who found an increase in the activation of the brain’s reward system during the presentation of attractive faces that presented a mildly happy expression compared to a neutral expression. One limitation of our study is that the male and female prototypes were not comparable, with the result that for females the difference between attractive and less attractive faces was more obvious than for males (pre-study). It may therefore be that the differential effect of happiness on attractiveness judgements in Experiment 1 and the differential effect of attractiveness on happiness judgements in Experiment 2 for male and female faces may have resulted from this difference. Nevertheless, this possibility does not detract from our findings that the judgement of attractiveness was influenced by the intensity of a smile and that the judgement of happiness was influences by the attractiveness of a face. Another limitation of our study may be that we only manipulated the shape of the stimuli. Shape can be seen as an important cue to attractiveness but facial attractiveness depends on more than shape. For example facial colour and skin texture also influence the perceived attractiveness (Jones, DeBruine, Little, Conway, & Feinberg, 2006).

Nevertheless, our results provide clear evidence that a happy facial expression influences the judgement of attractiveness, in that a smile may outweigh an attractive facial shape. It will have to be the aim of future research to include other emotional expressions in different intensities. In conclusion, the findings of the present study suggest that the judgement of attractiveness is influenced by the emotional expression of a face and, conversely, the judgement of emotional expression is affected by the attractiveness of the face. In Experiment 1 we found that a face that was manipulated to be less attractive but more smiling was preferred over the same face that was made more attractive but less smiling. So far studies have revealed a general influence of happiness on the evaluation of attractiveness. The present study extended on previous findings by showing that a smile can compensate for relative unattractiveness. In addition to this, Experiment 2 showed a reciprocal influence between facial attractiveness and emotional expression: It was easier to choose the happier of two faces if the happier face was also more attractive. We were thus able to demonstrate that facial attractiveness influences the recognition of happiness. This result is not intuitive, and might be explained by a more pronounced interest in more attractive faces. Most importantly, our results suggest a clear interdependency of the processing of facial attractiveness and emotional expression. Manuscript received 8 May Revised manuscript received 13 June Manuscript accepted 14 June First published online 22 July

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