News Finding: Two more experiments indicated that the angle of the eyebrows drove this effect -- downward-tilted heads had eyebrows that appeared to take more of a V shape, even though the eyebrows had not moved from a neutral position, and this was associated with perceptions of dominance.
Paper Finding: Finally, the indirect effect of head tilt on perceptions of dominance via eyebrow V-shape was significant, b =.16, p < .01, 95% CI [.11 to .22].
News Context: That is, participants rated downward-tilted heads as more dominant even when they could only see the eyes and eyebrows; this was not true when the rest of the face was visible and the eyes and eyebrows were obscured. Two more experiments indicated that the angle of the eyebrows drove this effect -- downward-tilted heads had eyebrows that appeared to take more of a V shape, even though the eyebrows had not moved from a neutral position, and this was associated with perceptions of dominance. "In other words, tilting the head downward can have the same effect on social perceptions as does lowering one's eyebrows -- a movement made by the corrugator muscle, known as Action Unit 4 in the Facial Action Coding System -- but without any actual facial movement," say Witkower and Tracy.
Paper Context: The direct effect of head tilt on perceptions of dominance while controlling for eyebrow V-shape was significant but partially attenuated, b = .17, t = 3.26, p < .001, 95% CI: [.07 to .27]. Finally, the indirect effect of head tilt on perceptions of dominance via eyebrow V-shape was significant, b =.16, p < .01, 95% CI [.11 to .22]. Follow-up models outlining the a and b pathways while estimating additional random slopes and covariates, or using different analyses (e.g., repeated measures ANOVA), did not change the statistical significance or the direction of other pathways in the model (see Table 1 and SOM-U).