For decades, researchers relied on the Delboeuf illusion to explain how the size and shape of the serving object effects how much we actually eat. In a recent 2012 study, scientists asked their participants to serve themselves soup in bowls of different sizes. The people who used larger bowls poured themselves more soup than those with smaller bowls. This is the classic understanding of the Delboeuf illusion.
Since then, restaurants responded by adjusting the size of serving plates. It depending, however, on their clientele. For health-conscious venues, the plates got smaller. But for fast food restaurants, “supersizing” was all the rage. And ever since, the food industry has invested billions in finding what works best for their customers, what can be rightly stated as a manipulation they enjoyed.
But some Israeli researchers are questioning all of this, not that it’s wrong per se, but that it’s not necessarily the size that matters. What matters more is your level of hunger. Using the Delboeff illusion again, they did the standard object manipulation, only this time their participants hadn’t eaten for three hours whereas the other group ate just one hour before.
The findings were eye-opening. Those who were considerably hungry were to accurately size up the true quantity of food regardless of the plate size while the group who just ate experienced the classic Delboeff illusion; the size of the object cause them to misrepresent the service size.
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Researchers believe that this latest study show evolutionary tendencies in action. In other words, the more hungry we are, the more attuned we become toward objective reality, that is, the true situation. When we’re not so hungry, we are easily manipulated by the Delboeff illusion. Put slightly differently, the more hunger becomes an existential need, the more focused and accurate our assessment of our world becomes.
An interesting follow-up study would be to extend the length of food deprivation to see at what point (in time) the accuracy of assessment begins to veer off.