The psychologists Gordon Allport and Leo Postman showed more than half a century ago that preconceptions about race distorted human judgment and sometimes caused people to recall things that had never happened. Their best-known study mimicked the parlor game “telephone.”

In this version, subjects who often included students were shown a now-famous slide depicting typical passengers in a New York City subway car. At the center of the image stand two figures: a black man dressed in a natty suit and a white man in shirtsleeves holding a straight razor.

After being shown the slide, subjects were asked to describe it to others who had not seen it. These people then described it to others, who then passed on their descriptions as well. Those who had heard the story secondhand were then asked to recount it. More than half the time, the razor was said to be held not by the white man but by the well-dressed black man, who was sometimes described as brandishing it wildly.

This country has changed considerably in the more than 60 years since these data were published. But the mental calculus that shifted the razor into the black man’s hand is still very much a part of the American scene. It comes into play every day in courtrooms, in city streets and especially in job interviews.

People who believed that racism was on the wane were mightily shocked by the research into the effect of race on hiring policies that appeared in the 2007 book “Marked: Race, Crime and Finding Work in an Era of Mass Incarceration,” by the Princeton sociologist Devah Pager. After sending carefully selected test applicants to apply for low-level jobs with hundreds of employers, Ms. Pager found that criminal convictions for black men seeking employment were, in many contexts, “virtually impossible to overcome,” partly because those convictions reinforced powerful, longstanding stereotypes.