People don't eat just because their stomach says they're hungry, says Brian Wansink, author of "Mindless Eating: Why We Eat More Than We Think," (Bantam Books, $25).

All kinds of factors cue people to eat, and overeat: the size of a plate or bowl, an alluring recipe title, a fancy wine label, whether a drink is served in a wide or narrow glass, whether a brownie is served on a napkin or a nice plate, or simply because the food is within reach.

As the director of the Cornell Food and Brand Lab, Wansink studies the hidden persuaders that lead people to eat, and overeat. He recently demonstrated his mind-game research during the TV show "20/20."

After patrons in a restaurant dished up their own pasta, a restaurant employee "accidentally" sneezed or coughed on the food, apologized profusely and told them to go back and fill a new plate of food. Only this time, they were given a bigger plate. And they took 20-25 percent more pasta than when they used a small plate. But when questioned afterward, patrons were unaware that they had "mindlessly" piled on a bigger helping.

The "restaurant employee" who was scripted to "accidentally" cough or sneeze on the food was Collin Payne, Wansink's associate director of consumer research, who grew up in South Ogden and earned a doctorate in social psychology from Brigham Young University.

"That's what's so fun about these experiments; it's almost like a 'Candid Camera' type of thing," said Payne in a telephone interview from the Cornell lab in Ithaca, N.Y. "We have to come up with ways that we can naturally replicate what happens in the real world. In the case of the experiment with the big plates, we had to figure out a way to have the individuals serve themselves a second plate without making them think something weird was going on. The sneezing or coughing was something plausible."

Payne said one of the most fascinating projects he and Wansink did showed the effect a wine label has on dining. One night at a restaurant, all the diners were offered a complimentary glass of wine. Although everyone was given the same cheap, $2-a-bottle wine, half were told it was from a fancy new California winery, and the other half were told it came from North Dakota — a region not known for its fine wines. The wine was labeled accordingly.

Both groups drank nearly all of the free wine. But those who thought they were drinking California wine ate 11 percent more of their food and lingered an average of 10 minutes longer at the table.

"Who would think that the same wine, but just labeled to be from a different part of the country, would not only influence their taste perception of the wine but how much they ate in a dinner situation?" Payne said. "It's hard to believe that a simple environmental change could have that large of an effect. It's unbelievable how gullible we are in terms of advertising and marketing, and how our senses trick us."