Before she sang, Ms. Boyle seemed to be merely a frumpy 47-year-old unemployed church volunteer who lived alone with her cat, Pebbles, and had, she said, “never been kissed” (a claim that she later took back).

Now, after the video of her performance went viral, a flurry of commentary has focused on how we stereotype people into categories, how we fall victim to the prejudices of ageism or look-ism, and how we should learn, once and for all, not to judge books by their covers. But many social scientists and others who study the science of stereotyping say there are reasons we quickly size

people up based on how they look. Snap judgments about people are crucial to the way we function.

They would even agree with Ms. Boyle herself, who said after her performance that while society is too quick to judge people by appearance, “There is not much you can do about it; it is the way they think; it is the way they are.” — The New York Times