Abstract
Perceived social traits, such as dominance and trustworthiness, affect other people’s behaviour. For example, gaze following behaviours are modulated by perceived face dominance (Ohlsen et al., 2013). While the impact of social traits has been consistently found in high-level face perception, it is unclear whether social traits also influence low-level facial information processing. To this end, we investigated how perceived face dominance affects the perception of face size. We used a robust perceptual illusion to measure the perception of face size: when two identical faces are presented vertically (one above the other), the bottom one appears bigger (Sun et al., 2012). We hypothesize that if face dominance modulates the perception of face size, this will be reflected in the magnitude of the illusion. We used a set of Dominant and Submissive computer-generated faces (Oosterhof & Todorov, 2008), which were verified by human raters. Participants saw two identical vertically presented faces and used the mouse to decide which face was bigger. To probe the generality of this effect, we tested this effect across three countries (N = 30/country) with faces from three races (African, Asian, and Caucasian). Across the three countries, participants showed a significant bias in choosing the bottom face as the bigger one (Mean bottom responses = 72.03%, p < .001), replicating the illusion. More importantly, Dominant faces led to a stronger illusion than Submissive faces (p = .009), suggesting face dominance modulates the perception of face size. We did not find a significant effect of face race or country. Together, the converging findings from the three countries indicate that perceived dominance amplifies the perceived size of the bottom face. This effect supports a top-down perceptual modulation account, by which high-level representations of social traits influence low-level visual processing.