Jennifer L. Eberhardt, 49, an associate professor of psychology at Stanford University, studies the effect of unconscious ideas about race on the workings of the criminal justice system. She was one of 21 winners of 2014 MacArthur “genius” grants.

Interest in her work has grown after the deaths of black suspects at the hands of police officers in Missouri and New York. We spoke for two hours in New York in September and again by telephone on Jan. 1. Here is an condensed and edited version of our conversations.

WHEN YOUR MACARTHUR WAS ANNOUNCED, IT WAS SAID YOU HAD SHOWN HOW CRIMINAL SENTENCING WAS RELATED TO SKIN COLOR AND RACIAL STEREOTYPING. HOW DID YOU DO THAT?

The particular study they were referring to was on the death penalty. We gathered photographs of people convicted of capital crimes and who were eligible for a death sentence. We then cropped them and asked Stanford students to rate how stereotypically black the faces appeared to be.