Unit Bias
The tendency to believe that a single unit of something — one serving, one portion, one item — is the appropriate amount, regardless of its actual size. A bigger plate leads to a bigger meal.
EverydayConcepts.io
Origin
Identified by psychologists Andrew Geier, Paul Rozin, and Gheorghe Doros in a 2006 study. They found that people consistently treated "one unit" as the right amount — whether it was one bowl, one plate, or one bag — regardless of actual size. Larger plates led to larger portions consumed. The finding has major implications for nutrition policy, packaging design, and understanding why supersizing works.
Updated February 22, 2026