Eyelid-openness and mouth curvature influence perceived intelligence beyond attractiveness

Impression formation is profoundly influenced by facial attractiveness, but the existence of facial cues which affect judgments beyond such an "attractiveness halo" may be underestimated. Because depression and tiredness adversely affect cognitive capacity, we reasoned that facial cues to mood (mouth curvature) and alertness (eyelid-openness) affect impressions of intellectual capacity. Over 4 studies we investigated the influence of these malleable facial cues on first impressions of intelligence. In Studies 1 and 2 we scrutinize the perceived intelligence and attractiveness ratings of images of 100 adults (aged 18-33) and 90 school-age children (aged 5-17), respectively. Intelligence impression was partially mediated by attractiveness, but independent effects of eyelid-openness and subtle smiling were found that enhanced intelligence ratings independent of attractiveness. In Study 3 we digitally manipulated stimuli to have altered eyelid-openness or mouth curvature and found that each independent manipulation had an influence on perceptions of intelligence. In a final set of stimuli (Study 4) we explored changes in these cues before and after sleep restriction, to examine whether natural variations in these cues according to sleep condition can influence perceptions. In Studies 3 and 4 variations with increased eyelid-openness and mouth curvature were found to relate positively to intelligence ratings. These findings suggest potential overgeneralizations based on subtle facial cues that indicate mood and tiredness, both of which alter cognitive ability. These findings also have important implications for students who are directly influenced by expectations of ability and teachers who may form expectations based on initial perceptions of intelligence.