New research finds a convict is more likely to be sentenced to death if he has an untrustworthy face.

Death chamber and electric chair at Sing Sing Prison in 1923. (Photo: Everett Historical/Shutterstock)

If you support the death penalty, in spite of the many compelling arguments to the contrary, you must concede it is only morally acceptable if carried out in a fundamentally fair way. Surely the decision to impose this most final of punishments must not be subject to the biases or whims of jurors or jurists.

Well, newly published research suggests who lives and who dies is determined, to a significant degree, by gut-level instinct. It finds the decision to impose a death sentence is based in part on a completely irrational construct: Whether the convict has what is perceived as a trustworthy face.

This finding "suggests an alarming bias in the criminal justice system," conclude the study's co-authors, University of Toronto psychologists John Paul Wilson and Nicholas Rule. "Put simply, one's face may determine one's fate, at least in the judicial domain."

"Perceptions of trustworthiness from faces, which have high consensus but questionable validity with regard to actual behavior, affect criminal sentencing."

It has long been known that, consciously or not, people tend to size up strangers based on their facial characteristics. A 1996 study found we use such visual metaphors as "wide-eyed innocence" and "crooked character" to quickly determine whether someone is worthy of our trust.

But would this sort of mental shortcut come into play when making the weighty decision of sentencing a convicted murderer to either death or life in prison? To find out, Wilson and Rule collected photographs of 371 men on Florida's death row (nearly the entire population), and an equal number of inmates convicted of first-degree murder but sentenced to life imprisonment.

The 742 images were broken up into sets of around 100 each. Individual faces were then rated for trustworthiness (along with other factors including Afrocentricity and attractiveness) by 208 Americans recruited online via Amazon's Mechanical Turk.

"We found that people who look less trustworthy were more often sentenced to death for first-degree murder," the researchers report in the journal Psychological Science. "Perceptions of trustworthiness from faces, which have high consensus but questionable validity with regard to actual behavior, affect criminal sentencing."

It's conceivable, of course, that our instinctive judgment of trustworthiness is sometimes accurate. So to take that issue out of the equation, Wilson and Rule collected a second set of facial images—this one from the Innocence Project. It featured 37 men who were wrongly convicted of, and served time in prison, for a serious crime before being exonerated. Twenty had been sentenced to life in prison; 17 received the death penalty.

Their faces were judged for trustworthiness by an online panel of 39 Americans. Once again, "faces perceived as less trustworthy were more likely to be sentence to death," the researchers report. "Thus facial appearance affects real-world criminal sentencing independently of actual guilt."

Altogether, the results paint "a somewhat alarming picture of how systems of legal punishment are vulnerable" to irrational decision-making, the researchers conclude. "People who look less trustworthy receive harsher criminal sentences," they write, "and overgeneralization of traits from their faces appears to be responsible for this effect."

Can a system with such egregious built-in bias truly be justified?

Findings is a daily column by Pacific Standard staff writer Tom Jacobs, who scours the psychological-research journals to discover new insights into human behavior, ranging from the origins of our political beliefs to the cultivation of creativity.