Adult minds are so keen at spotting race, gender and age that we can correctly guess those features from nothing more than a black-and-white silhouette, new experiments show.

"It's surprising how much information the silhouette provides," said Stanford University cognitive psychologist Nicolas Davidenko, who led the study. "We rarely have to identify a person in a silhouette, yet in the experiment, people can do that without difficulty."

The way that our brains process faces, he said, seems so flexible that our minds can even assign people to social and biological categories drawing only on views that occur less commonly in our daily lives—including black-and-white profiles.

He has also found people are 85 percent accurate in identifying a person's race from a black-and-white image.

For example, the width of a brow, length of chin and protrusion of a nose makes a face appear more masculine.