Eighty-five food and nutrition experts were invited to a self-serve ice cream social at the university, and were each randomly assigned either 17- or 34-ounce bowls and either 2- or 3-ounce serving spoons.
"Just doubling the size of someone's bowl increased how much people took by 31 percent," said lead author and director of Cornell's Food and Brand Lab, Brian Wansink. "We also saw that giving people a scoop that was a little bit larger increased things by about 14.5 percent."
Wansink said the evidence suggested that, while 4 ounces of ice cream in a small bowl may look fine, the same amount in a bigger bowl can lead people to over serve themselves. Even food and nutrition experts, who can judge the calories in portion sizes more accurately than the average ice cream consumer, were fooled.
"The fact that even (nutritionists) end up being tripped up by these cues just helps to show how ubiquitous and how subversive these illusions can be," said Wansink, who, along with his coauthors, intends to publish the results of the study in the September issue of the American Journal of Preventive Medicine.
This principle seems to be well understood by all-you-can-eat restaurants, which use relatively small bowls, spoons, plates and cups to limit consumers' self-serve portions.
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