People Evaluate Evidence in Strange Ways

"Count Today's Calories, And Check Your Wallet"
By Shankar Vedantam, The Washington Post, November 19, 2007

Excerpt;

Carnegie Mellon psychologist Carey Morewedge recently had volunteers sit before a bowl of M&Ms. He and his colleagues told some volunteers that a packet of M&Ms contained about 3/25 their daily recommended caloric intake. The researchers told other volunteers that a packet of M&Ms contained about 3/175 their weekly recommended calories. Volunteers were then allowed to eat as many M&Ms as they pleased.

A mathematician would say that the daily and weekly caloric numbers are equivalent, but the psychologists found that the two frames of reference made a big difference when it came to behavior. Volunteers asked to think about the weekly number of calories ate more than twice as many M&Ms as those asked to think about the daily number of calories.