Creativity is a defining human characteristic, but it is also notoriously hard to pin down. I recently wrote about the benefits of diverse perspectives in solving real-world problems, which reminded me of the psychology literature on measures of creativity. We psychologists specialize in measuring characteristics of people that are hard to define, like intelligence or personality. But within the broad literature of psychological testing, creativity is a particularly tough nut to crack. Dr. Teresa Amabile of the University of Iowa pointed out that all studies of creativity begin with a significant "criterion problem," in other words, how do we define the thing that we want to study? To some extent, whether or not a work is "creative" is in the eye of the beholder. In my own Master's thesis on creativity, I operationally defined creativity as "being a student in art school," which I compared to "being a business student." But are artists i...