First impressions of a new face are shaped by infection concerns

Abstract

Along with a classical immune system, we have evolved a behavioral one that directs us away from potentially contagious individuals. Here I show, using publicly available cross-cultural data, that this adaptation is so fundamental that our first impressions of a male stranger are largely driven by the perceived health of his face. Positive (likeable, capable, intelligent, trustworthy) and negative (unfriendly, ignorant, lazy) first impressions are affected by facial health in adaptively different ways, inconsistent with a mere halo effect; they are also modulated by one's current state of health and inclination to feel disgusted by pathogens. These findings, which replicated across two countries as different as the USA and India, suggest that instinctive perceptions of badness and goodness from faces are not two sides of the same coin but reflect the (nonsymmetrical) expected costs and benefits of interaction. Apparently, pathogens run the show-and first impressions come second. Lay Summary: Our first impressions of strangers (whether they seem trustworthy, intelligent, unfriendly, or aggressive) are shaped by how healthy their faces look and by our unconscious motivation to avoid infections. Bad and good impressions turn out to reflect the concrete, potentially vital, expected costs and benefits of interacting with our fellow humans. Apparently, pathogens run the show-and first impressions come second.

Keywords: behavioral immune system; disgust; face perception; first impressions; pathogen avoidance; sickness communication.

Figure 1.

First impressions of health-unrelated assets (left panel) and liabilities (right panel) of a male stranger as a function of his perceived facial health. Data are separately plotted for participants living in India (solid symbols) and the USA (open symbols). All slopes are steeper for assets than for liabilities, suggesting that facial health enhances a stranger’s apparent assets more than it reduces his liabilities (especially in India: in the right panel, the slope is shallower for solid than for open symbols, perceived health × country, beta = 0.12, P < 0.0001). Assets (likeable, trustworthy, intelligent, capable) and liabilities (ignorant, lazy, unfriendly, aggressive) were estimated on a scale from 0 to 6. Health was estimated on a scale from –5 (very ill) to +5 (very healthy). Error bars indicate one standard error around the mean.

Figure 2.

People’s motivation to avoid infections affects their first impressions of a new face. Data are separately plotted for participants living in India (solid symbols) and the USA (open symbols). Left panel: health-unrelated negative attributions to a stranger increase with the observer’s pathogen disgust sensitivity (subdivided, for clarity of presentation, in intervals of 10 percentiles each). Middle and right panels: health-unrelated negative (middle) and positive (right) attributions to a stranger depend on the observer’s current health conditions. ‘Healthier’: all participants whose self-reported health was ‘very good’ (which turned out to be the bottom 19% of the variable ‘Illness’, N = 691). ‘Sicker’: all participants whose health was either ‘average’, ‘fairly poor’, ‘poor’, or ‘very poor’ (which turned out to be the top 19% of the variable ‘Illness’, N = 705). Error bars indicate one standard error around the mean.