An elegant study, formulated by psychologists Ellen Langer and Alia Crum at Harvard University in 2007, examined the effect of simply being told that you are doing something healthy. Eighty-four female room attendants working in various hotels were divided into two groups: one was told that cleaning hotel rooms was "good exercise" and "satisfies the Surgeon General's recommendations for an active lifestyle", along with elaborate explanations of how and why; the other group did not receive this cheering information, and just carried on cleaning hotel rooms. Four weeks later, the 'informed' group perceived themselves to be getting significantly more exercise than before, and showed a significant decrease in weight, body fat, waist-to-hip ratio and body mass index. Amazingly, both groups were still reporting the same amount of activity.