New York, July 16 (IANS): The perceived trustworthiness of an inmate's face may determine the severity of the sentence he receives, a study says.

The study, published in Psychological Science, found that inmates whose faces were rated as low in trustworthiness by independent observers were more likely to have received the death sentence than inmates whose faces were perceived as more trustworthy.

"The American justice system is built on the idea that it is blind to all but the objective facts. Of course, this ideal does not always match reality," said study co-author John Paul Wilson, a psychological scientist at the University of Toronto.

"Here, we have shown that facial biases unfortunately leak into what should be the most reflective and careful decision that juries and judges can make - whether to execute someone," said co-author Nicholas Rule.

The researchers obtained photos of 371 male inmates on death row in Florida and asked an online panel of 208 American adults to look at the photos and rate them on trustworthiness using a scale from 1 (not at all trustworthy) to 8 (very trustworthy).

The researchers found that inmates who had received the death sentence tended to be perceived as less trustworthy than those sentenced to life in prison.

In fact, their analyses showed that the less trustworthy a face was deemed, the more likely it was that the inmate received the death sentence.

The inmates in the two groups had committed crimes that were technically equally severe, and neither sentence would have allowed for the inmates to return to society - as such, the motivation to protect society could not explain the harsher punishment doled out to the less trustworthy looking individuals, the study said.

More striking, a follow-up study showed that the link between perceived trustworthiness and sentencing emerged even when participants rated photos of inmates who had been sentenced but who were actually innocent and were later exonerated.