"You might think it's obvious that one person is smarter than another," says researcher Adrian Owen, senior scientist at the Medical Research Council Cognition and Brain Sciences Unit in Cambridge, U.K. "But there are few more controversial areas of science than the study of intelligence and, in reality, there's not even agreement among researchers about what this word actually means. Unlike weight and height, which are unambiguous, there is no absolute measure of intelligence, just as there are no absolute measures of honesty or physical fitness. ... Now my team at the UK Medical Research Council's Cognition and Brain Sciences Unit in Cambridge has come up with the ultimate test of intelligence."