We often look to people’s faces for signs of how they’re thinking or feeling, trying to gauge whether their eyes are narrowed or widened, whether the mouth is turned up or down.
But findings published in the June 2019 issue of Psychological Science, a journal of the Association for Psychological Science, show that facial features aren’t the only source of this information – we also draw social inferences from the head itself.
“We show that tilting one’s head downward systematically changes the way the face is perceived, such that a neutral face—a face with no muscle movement or facial expression – appears to be more dominant when the head is tilted down,” explain researchers Zachary Witkower and Jessica Tracy of the University of British Columbia
“This effect is caused by the fact that tilting one’s head downward leads to the artificial appearance of lowered and V-shaped eyebrows – which in turn elicit perceptions of aggression, intimidation, and dominance.”
“These findings suggest that ‘neutral’ faces can still be quite communicative,” Witkower and Tracy add.
“Subtle shifts of the head can have profound effects on social perception, partly because they can have large effects on the appearance of the face.”
Although researchers have investigated how facial muscle movements, in the form of facial expressions, correlate with social impressions, few studies have specifically examined how head movements might play a role.
Witkower and Tracy designed a series of studies to investigate whether the angle of head position might influence social perception, even when facial features remain neutral.
In one online study with 101 participants, the researchers generated variations of avatars with neutral facial expressions and one of three head positions: tilted upward 10 degrees, neutral (0 degrees), or tilted downward 10 degrees.
The participants judged the dominance of each avatar image, rating their agreement with statements including “This person would enjoy having control over others” and “This person would be willing to use aggressive tactics to get their way.”
The results showed that participants rated the avatars with downward head tilt as more dominant than those with neutral or upward-titled heads.
A second online study, in which 570 participants rated images of actual people, showed the same pattern of results.
Additional findings revealed that the portion of the face around the eyes and eyebrows is both necessary and sufficient to produce the dominance effect.
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.
“Head tilt is thus an ‘action unit imposter’ in that it creates the illusory appearance of a facial muscle movement where none in fact exists.”
Given these intriguing results, the researchers are continuing to investigate the influence of head tilt on social perception, exploring whether the effects might extend beyond perceptions of dominance to how we interpret facial expressions of emotion.
Ultimately, Witkower and Tracy note, these findings could have practical implications for our everyday social interactions:
“People often display certain movements or expressions during their everyday interactions, such as a friendly smile or wave, as a way to communicate information.
Our research suggests that we may also want to consider how we hold their head during these interactions, as subtle head movements can dramatically change the meaning of otherwise innocuous facial expressions.”
A facial action imposter: How head tilt influences perceptions of dominance from a neutral face
Facial expressions – that is, changes to facial appearance caused by facial muscle activation –fundamentally shape social perceptions (Hareli, Shomrat, & Hess, 2009; Knutson, 1996; Ekman & Oster, 1979).
Here, we propose and test a novel account of social perception from the face. We argue that head position plays a critical role in face perception, by causing the appearance of the face to change – paralleling the consequences of facial expressions – without utilizing facial musculature.
Specifically, head position in the form of downward-pitch rotation, or tilt, can co-opt the psychology of facial-expression perception by creating the visual illusion of facial dynamics:
Tilting the head downward causes the eyebrows to take on an apparent V- shape and become lowered – the same appearance cues associated with Action-Unit (AU) 4 (i.e., corrugator activation; Ekman & Friesen, 1978)—even when the face in fact remains neutral (see Figure 1).
As a result, although tilting the head downward does not involve AU4, it may function as an imposter of that action unit by causing the same appearance changes.
Although prior research has not examined whether tilting the head downward causes the appearance of illusory eyebrow movement, studies have shown that actual eyebrow movement in the form of corrugator activation (i.e., AU4) increases perceptions of social rank (Keating & Bai, 1986), and that neutral faces with artificially lowered and V-shaped brows are perceived as high ranking and physically strong, threatening, or dominant (Toscano, Schubert, & Sell, 2014; Schmid-Mast & Hall, 2004; Neth & Martinez, 2009).
However, these results are based on unnatural manipulations of facial features. We believe that these same changes in facial appearance naturally occur when the head is tilted down (assuming similar viewing conditions; Kappas, Hess, Barr, & Kleck, 1994), and shifts in head movement therefore indirectly influence
social perceptions via facial appearance changes (see also Martinez, 2017).
In sum, the proposed action-unit imposter hypothesis posits that when the head is tilted down, the eyebrows appear to lower and take on a V-shape (cues associated with AU4; see Figure 1), and these changes in facial appearance cause observers to form perceptions of dominance.
Head tilt therefore functions as an action-unit imposter: causing the same effect as a facial-muscle movement, on an inactive face.
Figure 1. Visualization of the mechanism proposed by the novel action-unit imposter account. Top: neutral head and face. Bottom: downward-head tilt (left), and activation of AU4 (right). Both movements create the appearance of a V-shape and lowering of the eyebrows.
Prior researchers have suggested that head movements contribute to perceptions of dominance, but the direction and mechanism underlying this effect remain elusive. Several scholars have suggested that tilting the head downward is a closed and contracted nonverbal movement that makes individuals appear smaller (Mignault & Chaudhuri, 2003; Rule, Adams Jr, Ambady, & Freeman, 2012), thereby decreasing perceptions of dominance (Marsh, Yu, Schechter, & Blair, 2009; Blaker & van Vugt, 2014).
Similarly, Lyons and colleagues (2000) suggested that tilting the head down might alter the apparent curvature of the mouth, increasing the extent to which a slightly smiling target is perceived as happy, an emotion that communicates warmth and affiliation and should therefore decrease perceptions of dominance (Witkower, Tracy, Cheng, & Henrich, 2018).
Yet others have suggested exactly the opposite: that a downwards head tilt increases perceptions of dominance, by increasing the visible facial width- to-height ratio (vFWHr; Hehman, Leitner, & Gaertner, 2013) – a holistic facial metric associated with aggression and intimidation (Geniole, Denson, Dixson, Carré, & McCormick, 2015; but see Kosinski, 2017).
Our AU-imposter account, like the vFWHr hypothesis, and contrary to both the closed- and-contracted and mouth-curvature hypotheses, suggests that downwards-head tilt should increase perceptions of dominance from a neutral (i.e., completely inactive) face.
Critically, however, our account offers a novel visual mechanism to explain this effect. In eight studies (three reported in the SOM), we test our AU-imposter account and provide the first empirical evidence that head movements can shape social judgments by creating the illusion of facial action and thereby altering the appearance of a neutral (i.e., inactive) face.
Note. Pictured from left to right: downward head tilt, neutral head angle, upward head tilt. In all images, targets posed neutral facial expressions (i.e., no facial muscle movement).
More information: Zachary Witkower et al, A Facial-Action Imposter: How Head Tilt Influences Perceptions of Dominance From a Neutral Face, Psychological Science (2019). DOI: 10.1177/0956797619838762
Journal information: Psychological Science
Provided by Association for Psychological Science
