All Smiles are Not Created Equal: Morphology and Timing of Smiles Perceived as Amused, Polite, and Embarrassed/Nervous
Zara Ambadar, Jeffrey F. Cohn, and Lawrence Ian Reed
Department of Psychology, University of Pittsburgh, Pittsburgh, Pennsylvania
Abstract
We investigated the correspondence between observer judgments of smiles
and the morphological and dynamic characteristics of the smiles that
map onto those meanings. Morphological characteristics included co-activation
of Orbicularis oculi (AU 6), smile controls, mouth opening, amplitude,
and asymmetry of amplitude. Dynamic characteristics included duration,
onset and offset velocity, asymmetry of velocity, and head movements.
Observers (N=101) judged 122 smiles as amused, embarrassed, nervous,
polite, or other. Fifty-four smiles met criteria for classification
as perceived amused, embarrassed/nervous, polite, or other. Characteristics
of these smiles were measured using the Facial Action Coding System
(Ekman, Friesen, & Hager, 2002) and Automated Facial Image Analysis
(Cohn & Kanade, 2007). In comparison with perceived polite, perceived
amused more often included Orbicularis oculi co-activation (AU 6), open
mouth, smile controls, larger amplitude, larger maximum onset and offset
velocity, and longer duration. In comparison with perceived embarrassed/nervous,
perceived amused more often included AU 6, lower maximum offset velocity,
and smaller forward head pitch. In comparison with perceived polite,
perceived embarrassed more often included mouth opening and smile controls,
larger amplitude, and greater forward head pitch. Occurrence of the
AU 6 in perceived embarrassed/nervous and polite smiles questions the
assumption that this action together with a smile is sufficient to communicate
felt enjoyment. By comparing three perceptually distinct types of smiles,
we found that perceived smile meanings were related to specific variation
in smile morphological and dynamic characteristics.
Example of perceived Amused smile:
Example of perceived Embarassed/nervous smile:
Example of perceived Polite smile:
