Late last year, a little book called “Mindless Eating” started appearing in bookstores. It was written by Brian Wansink, a Cornell professor who has spent his career doing brilliantly mischievous experiments about the psychology of eating.

In one of my favorites, Mr. Wansink gave away five-day-old popcorn — “stale enough to squeak when it was eaten,” he wrote — to moviegoers one day at a theater in the Chicago suburbs. The crux of the experiment lay in the size of the buckets that held the popcorn. Some people got merely big buckets, while others received truly enormous ones. Both sizes held more popcorn than a typical person could finish.

Yet when the Wansink research team weighed the buckets after the movie, there was a huge difference in the amounts the two groups ate. Those with the bigger buckets inhaled 53 percent more on average, suggesting that a lot of stale popcorn is somehow more appealing than a little stale popcorn.

Over the years, Mr. Wansink has done similar experiments with everything from different-size dinner plates to bottomless bowls of tomato soup that are secretly connected to a tube underneath a restaurant table. His overarching conclusion is that our decisions about eating often have little to do with how hungry we are. Instead, we rely on cues like the size of a popcorn bucket — or the way we organize our refrigerator — to tell us how much to eat. These cues can add 200 calories a day to our diet, but the only way we’ll notice we are overeating is that our pants will eventually get too tight.