At the sight of that skull, I seemed to see all of a sudden ... the nature of the criminal – an atavistic being who reproduces in his person the ferocious instincts of primitive humanity and the inferior animals. Thus were explained anatomically the enormous jaws, high cheek-bones, prominent superciliary arches ... found in criminals, savages, and apes ... and the irresistible craving for evil for its own sake.
–Cesare Lombroso
The idea that facial metrics can provide information about a person’s propensity for unethical behaviour is making something of a comeback in the scientific literature. Recent research has correlated facial width-to-height ratios with:
(a) time spent in the penalty box among Canadian hockey players (Carré and McCormick 2008),(b) propensity to punish an opponent at a cost to oneself (Carré & McCormick 2008), and
(c) the propensity to selfishly exploit an opponent’s trust in a game context (Stirrat & Perrett 2010).
Not only can these “unethical” or “aggressive” tendencies be correlated to facial metrics via meticulous research – it turns out that casual observers are also able to predict a complete stranger’s propensity for aggression with surprising accuracy based only on a picture of that person’s face (Carré and McCormick 2009). The ethical implications of these findings are interesting and perhaps controversial (think racial and criminal profiling), but I will resist the temptation to go down that road at the moment, and instead focus on a recent study by Michael Haselhuhn and Elaine Wong titled Bad to the bone: facial structure predicts unethical behaviour.
Three things in particular attracted me to this paper: (i) the author’s use of the term ‘unethical’ which in my mind is subjective and imprecise; (ii) their reference to William March’s classic novel The Bad Seed and its conclusion that some people are just ‘born evil’; and (iii) the final sentence of the discussion “Perhaps some men truly are bad to the bone.” In truth, it was ridiculousness that drew me in, but nonetheless, let us proceed with the science!
Haselhuhn and Wong summarize their main result as follows:
...we show that genetically determined physical traits can serve as reliable predictors of unethical behaviour ... Specifically, we identify a key physical attribute, the facial width-to-height ratio, which predicts unethical behaviour in men.
In a first experiment, the authors arranged for 96 pairs of Business Admin students to participate in a negotiation exercise (conducted via email). Each pair consisted of a ‘buyer’ and a ‘seller’. Sellers were told that the property they were selling must not be commercially developed whereas buyers were instructed to obtain the property specifically for commercial development. The researchers quantified ‘unethical behaviour’ based on whether or not a buyer explicitly misstated his or her intentions at any point during the email negotiations.
In a second study, 103 undergraduates completed an online survey designed to assess their own ‘sense of power’ and then were allowed to enter a lottery for a chance to win a $50 gift card. The number of times that a student could enter the lottery was to be determined by a single roll of two dice (simulated at random.org). Because there was no oversight when students inputted the result of their dice roll at the end of the survey, there was nothing stopping participants from cheating and entering a higher number than was actually rolled (thereby increasing their chance of winning the gift card). Furthermore, because the dice roll was random, researchers were able to quantify cheating (at the group level, but not the individual level) based on deviations from the expected average roll of 7. For both experiments, two research assistants measured facial width-to-height ratios (hereafter ‘facial WHR’) of all participants based on school photographs (inter-rater agreement was high, r = 0.758).
So, what happened? In the first study, 18/96 buyers engaged in explicit deception during the email negotiation. Based on logistic regression, the probability of deception significantly increased with increasing facial WHR for men, while women’s facial WHR was not significantly related to deception. In the second study, the average reported dice roll from 103 participants was 7.76, significantly greater than what would be expected by random chance (i.e. 7.00), and therefore indicative of cheating. The reported dice roll (and therefore the incidence of cheating) did not differ between men and women. Just as before, ‘unethical behaviour’ (reported dice roll) was significantly and positively related to facial WHR for men, but not significantly influenced by facial WHR for women.
Recall that in the second study, participants also completed a survey about their own sense of power. It turns out that sense of power was positively related to both facial WHR and reported dice roll for men but unrelated to both variables among women. Some statistical voodoo (similar to path analysis) allowed the researchers to conclude that sense of power mediated the relationship between facial WHR and cheating behaviour among men.
Holy eff, right? I’m pretty amazed by these data. Before reading the paper, I expected that I would take issue with their analyses or conclusions, but the study was in fact well done. The only issue I take is with the authors’ claim (referring to the second experiment) that
...our approach introduces potential noise to the data as, for example, men with smaller facial WHRs may legitimately roll and report higher dice totals. Thus, testing for cheating behaviour using this paradigm represents a conservative test of our hypotheses.This is simply untrue. It is equally likely that men with larger facial WHRs might legitimately roll and report higher dice totals. Their approach is imprecise, but not ‘conservative’. A more precise way to test the relationship between facial WHR and cheating would be to use the difference between reported dice rolls and actual dice rolls as a dependent variable. This would require an experimental modification allowing the researchers to know with certainty what each participant actually rolled (e.g. using cameras, software tracking, etc.). Nonetheless, the results seem robust.
So then, how could this relationship have evolved? Intuition would suggest that physical signals that reliably predict unethical behaviour should be selected against. If you’re trying to deceive or cheat someone, you don’t want to tell them up front. Haselhuhn and Wong suggest that a relationship between certain facial features and unethical behaviour could evolve through pleiotropic associations with sexually selected traits such as aggression and dominance. If females like to mate with dominant males, and dominance is correlated both with certain facial features and unethical behaviour, than unethical behaviour may come to be associated with those same facial features.
Importantly, the correlation between facial WHR and unethical behaviour demonstrated by Haselhuhn and Wong does not necessarily imply that some people are ‘born evil’. For starters the effect sizes they reported were fairly small – facial WHR explained a relatively small proportion of the variance in propensity to cheat and deceive. Second, as the authors point out
...it is important to recognize that other developmental processes may play an important part in forming these links ... one possibility is that men with greater facial WHRs are perceived and treated by others in ways that encourage unethical action (i.e. a self-fulfilling prophecy).Again, although the reported relationships seem to be robust, I see no data here or elsewhere supporting the idea that some men are “bad to the bone”.
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Haselhuhn, M., & Wong, E. (2011). Bad to the bone: facial structure predicts unethical behaviour Proceedings of the Royal Society B: Biological Sciences DOI: 10.1098/rspb.2011.1193
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