Shared Perceptual Basis of Emotional Expressions and Trustworthiness Impressions from Faces Nikolaas N. Oosterhof and Alexander Todorov Presented by: Patricia Sayegh March 15 th 2010

Background dsa Social cognition and social neuroscience lab: His research is focused on the cognitive and neural mechanisms of person perception, in particular on face perception An assistant professor of psychology and public affairs at Princeton University, Nikolaas Oosterhof: Alexander Todorov:

Introduction People use information about the dynamic changes in the face to understand the mental state of others. We use facial features to help us identify a persons identity. ▫Judge trustworthiness, aggressiveness, dominance. ▫Thus facial features will affect important social outcomes. Previously, Blair et al. (2004) observed that Afro-American features predict criminal- sentencing.

Cesare Lombroso ( ): An Italian criminologist and founder of the School of Positivist Criminolgy. Believed that criminals could be identified based on their physical defects, specific physiognomic attributes. large jaws, high cheekbones flattened/ squashed nose thin beards and hair sloping foreheads fleshy lips expressive faces small wandering eyes thick and close eyebrows Introduction Previously, Blair et al. (2004) observed that Afro-American features predict criminal- sentencing. Thick close eyebrows Sloping forehead Thin hair

Introduction Based on our interpretation of a single, static aspect of ones appearance, we make spontaneous and rapid options about their character. ▫Likability, trustworthiness, competence and aggressiveness ( just on appearance!) Suggests that our judgments are based on subtle facial cues. Emotion overgeneralization hypothesis: ▫The emotional expressions we perceive from neutral faces affect the traits or behavioural tendencies we attribute to that face.

Introduction Based on their past work, they found that happiness and anger ratings were significantly correlated with trust and distrust ratings. Angry and happy ratings are based on subtle facial cues like: ▫Angry: eyebrows become more U-shaped and the mouth more ^ -shaped. ▫Happy: eyebrows become more ^ -shaped and the mouth more U-shaped. Our judgments are based on subtle facial cues. Emotion overgeneralization hypothesis: ▫The emotional expressions we perceive from neutral faces affect the traits or behavioural tendencies we attribute to that face.

If our judgments are based on subtle facial cues then how will angry versus happy faces affect our rating of trust?

Hypothesis/Prediction Hypothesis: expressions of anger and happiness are related to perceptions of trustworthiness. Prediction: ▫a) untrustworthy angry faces should be perceived as angrier than trustworthy faces expressing the same emotion. ▫b) trustworthy happy faces should be perceived as happier than untrustworthy faces expressing the same emotion.

Methods Participants: ▫60 undergraduate students  21 for selection of trustworthiness of neutral faces  39 participated in an animation study Facial stimuli: ▫96 computer generated faces ▫Emotionally neutral bald male Caucasian faces ▫Rated on a scale from 1 to 8 on trustworthiness ▫Picked the top 5 trustworthy and 5 untrustworthy faces for the animation study.

Methods Animation study:Animation study ▫51 frames of computer generated faces ▫Emotional expressions were linearly added to each face  Used Facegen’s Anger and SmileOpen happy expression control

Methods Animation study:Animation study ▫Started with neutral face (frame 1) and emotion was added to either 25% or 50% (frame 51)  Condition1: weak happy (25%)  Condition2: medium happy (50%)  Condition3: weak angry (25%)  Condition4: medium angry (50%)

Incongruent  Emotion added to same face  40 faces (10 faces x 2 emotions x 2 strength) Methods 3 animations: Face stimuli Congruent  Same trust level at start and end.  Face identity changes  Different trust level at start and end.  Face identity changes Participants were asked to judge how happy or angry end face became. Rated expression on a continuous slider scale

Difference in perceived emotion was augmented when identity and trustworthiness changed. F(1, 38) = 114.9, p <.001) Incongruent versus congruent t(38) = 6.55, p <.001 / t (38) = 10.89, p <.001 Incongruent versus same face t(38) = 8.26, p <.001 / t(38) = 12.13, p <.001 Expression of trustworthy faces were perceived as happier than untrustworthy faces. (M = 3.3, SD = 4.5, F(1, 38) = , p < ) Results: Perception of happy emotions

Incongruent versus congruent t(38) = 5.62, p <.001 / t (38) = 8.22, p <.001 Incongruent versus same face t(38) = 9.23, p <.001 / t(38) = 8.62, p <.001 Difference in perceived emotion was augmented when identity and trustworthiness changed. F(1, 38) = 85.73, p <.001) Expression of untrustworthy faces were perceived as angrier than trustworthy faces. (M = -.4, SD = 4.9, F(1, 38) = , p < ) Results: Perception of angry emotions

Perception of trustworthiness increases perception of an emotion. Same emotion was added to all faces BUT: ▫A) perceived trustworthy faces as happier than untrustworthy faces. ▫B) perceived untrustworthy faces as angrier than trustworthy faces. Discussion and Conclusions

Perception of trustworthiness increases perception of an emotion. Same emotion was added to all faces BUT: ▫A) perceived trustworthy faces as happier then untrustworthy faces. ▫B) perceived untrustworthy faces as angrier then trustworthy faces. Discussion and Conclusions Changes along the trustworthiness scale intensifies emotion perception, and are based on subtle facial cues.

The researchers concluded that: ▫Changes in expression of emotion affect trait impressions. ▫Valence is the main dimension along which emotionally neutral faces are evaluated.  Trustworthiness judgements as valance evaluator for neutral faces.  Valance evaluation triggers approach/avoid behaviour.  Happiness/ anger expression trigger approach/ avoid responses. Discussion and Conclusions

Focused on angry and happiness because previous work suggested that these emotion are affected by trustworthiness (Todorov, 2008). ▫Researchers acknowledge that other emotions may also affect trust judgements. ▫Which other emotions?  Maybe emotions where similar facial features are expressed.  Gender, facial maturity, similarity to self and facial textures have all been observed to interfere with trustworthiness. Discussion and Conclusions

Previously : trustworthiness is based on subtle facial cues of neutral faces (angry and happy expressions). In the current study, judgements on face trustworthiness affect perception of angry and happy emotions. Discussion and Conclusions Shared basis of perceptions of face trustworthiness and expressions of anger and happiness!

Hypothesis can account for dissociation between identifying a face and judging its trustworthiness. ▫Prosopagnosics can not identify/remember facial identity but can judge trustworthiness Todorov & Duchaine (2008). ▫Normal recognition of anger and happiness can preserve trustworthiness judgement. Discussion and Conclusions Shared basis of perceptions of face trustworthiness and expressions of anger and happiness!

Can you perceive emotion (happy or angry) and trustworthiness independently? ▫Is trustworthiness just a by-product of experiencing an emotion? What would be a good study to perform to try to distinguish shared or distinct neural pathways for happy, angry and trustworthiness? ▫To test this hypothesis more directly. Questions for discussion

Winston et al. (2002) Nature Neuroscience Some of the regions activated in the study by Winston and colleagues. -Fusiform gyrus (FG, green) and superior temporal sulcus (STS, red) process features of the face stimulus. Amygdala (AM, blue) associates perception of the face with an emotional response to the face. Insula (INS, purple) participates in representing this emotional response as a feeling about the person whose face we view. Activation in STS can also be modulated by the task, demonstrating top-down influences and suggesting that most information flows in both directions along this circuit.

Questions?

Analysis Design : ▫2 (emotion) x 2 (strength of emotion) x 2 (trustworthiness) x 3 (Morph). 2 x 2 x 2 x 3 Repeated ANOVA was performed.