Humboldt-Universität zu Berlin - Lebenswissen­schaftliche Fakultät - Institut für Psychologie

The functional equivalence hypothesis

This hypothesis states that there is a perceptual overlap between emotion expressions and certain trait markers, which then influences emotion communication. Specifically, Hess and colleagues propose the notion that some aspects of facial expressive behavior and morphological cues to dominance and affiliation are equivalent in their effects on emotional attributions.
The hypothesis has been tested with regard to gender related differences in morphology. Specifically, men's faces are generally perceived as more dominant, whereas women's faces are perceived as more affiliative. Mediation analyses confirmed that beliefs about the emotionality of men and women are mediated by these perceptions of dominance and affiliation (Hess, et al., 2005). In turn, judgments of emotional facial expressions by men and women are consistent with these perceptions (Hess, et al., 1997). A recent study further suggests that social role based stereotypes and facial morphology interact to create beliefs about a person's likely emotional reactions (Hess, et al., in press).
This line of research has also shown that facial expressions of anger and happiness entrain perceptions of dominance and affiliation respectively, and perceptually overlap with the morphological markers for dominance and affiliation (Hess, et al., 2009a). Specifically, in a double oddball design, an increase in reaction time is found when, from a perceptual perspective, the two types of faces belong to the same category (Campanella, et al., 2002). In Hess, et al. (2009), participants had to identify neutral faces that were embedded in a series of either angry or happy faces. They were significantly slower to identify highly dominant versus affiliative faces when the faces were embedded in the angry series. The converse was the case for affiliative faces embedded in the happy series. This supports the notion that anger and dominance on one hand, and happiness and affiliation on the other share perceptual markers. Further, angry expressions on dominant male faces are perceived as more threatening than the same expressions on more affiliative female faces and conversely, smiles on more affiliative female faces are perceived as more appetitive than smiles perceived on more dominant male faces (Hess, Sabourin, et al., 2007).
Hess, U., Thibault, P., Adams, R. B., Jr. & Kleck, R. E. (in press). The influence of gender, social roles and facial appearance on perceived emotionality. European Journal of Social Psychology.
Hess, U. Adams, R. B. Jr., Grammer, K., & Kleck, R. E. (2009). If it frowns it must be a man: Emotion expression influences sex labeling. Journal of Vision. 9(12), Article 19, 1-8.
Hess, U., Adams, Jr, R.B., Kleck, R.E. (2009). The face is not an empty canvas: How facial expressions interact with facial appearance. Philosophical Transactions of the Royal Society London B, 364, 497-3504.
Hess, U., Adams, J. B., Jr., & Kleck, R. E. (2009). The categorical perception of emotions and traits. Social Cognition, 27, 319-325.
Hess, U. Adams, R. B. Jr., Kleck, R. E. (2007). Looking at you or looking elsewhere: The influence of head orientation on the signal value of emotional facial expressions. Motivation and Emotion, 31, 137-144.
Hess, U., Sabourin, G., Kleck, R. E. (2007). Postauricular and eye-blink startle responses to facial expressions. Psychophysiology, 44, 431-435.
Hess, U., Adams, R. B. Jr., & Kleck, R.E. (2005). Who may frown and who should smile? Dominance, affiliation, and the display of happiness and anger. Cognition & Emotion, 19, 515-536.
Hess, U., Adams, R. B. Jr. & Kleck, R. E. (2004). Facial appearance, gender, and emotion expression. Emotion, 4, 378-388.