Most people unconsciously use visual cues such as a clean plate or the bottom of an empty bowl as a sign that it's time to stop eating, say scientists at Cornell University Food & Brand Lab. This means, of course, that we're not always paying attention to whether or not we're actually still hungry and the result can be mindless overeating that goes beyond the portion size we should actually be consuming.
In an attempt to outwit this problem, the Cornell team, led by Andrew Geier PhD, "segmented" food by placing red markers at the point in a stack of potato chips where the correct serving size ended and the gorging was about to begin.
A press release from the lab reported that study volunteers were given tubes of potato chips to eat while watching a movie. Red chips had been inserted at regular intervals into some of the participants' tubes as visual dividers. In some cases, the "stop signs" appeared every seventh chip and in others they were placed at every fourteenth chip. The subjects were variously told that the colored chips had been dyed and were left over from a previous experiment or that the markers were tomato basil chips being used to test a food company's flavor-mixing strategy. A control group was offered tubes of yellow chips with no red dividers.
The result was that the people who had the "stop signs" ate a whopping 50% less than those who didn't. Not only that, but the subjects with no dividers underestimated their intake by 12.6 chips while those with the red chips were almost 100% accurate.
"More research is needed to know exactly why this happens, but you can certainly put this effect to use," the release concluded. "Try a snack that is divided into smaller portions to help you see how much you are eating."