The Illusion of Size (a.k.a. Size Doesn’t Matter)

You may <a href="http://www.personal.psu.edu/staff/m/h/mhl100/2003_11_01_journal.html#id106847240357567848" title="How big is a serving of soup?">recall</a> I wondered how big was a cup of soup. Well, it turns out that a cup of soup is a cup &mdash; that is, eight ounces.



Well, Gretchen got me some <a href="http://www.amazon.com/exec/obidos/tg/detail/-/B0000636VM" title="Amazon.com: Kitchen &amp; Housewares: Emile Henry Couleurs 12-Ounce Individual Souffle Dish, Set of 2, Red">ramekins</a> for Christmas, and when I opened them, we both thought they looked a little small. We were almost ready to send them back, when we decided to conduct a little experiment.



<img src="http://www.personal.psu.edu/staff/m/h/mhl100/images/bowls.jpg" width="341" height="256" alt="Three soup bowls, apparently of different sizes, all hold the same amount." />



We took one of our cereal bowls (top left), one of our soup bowls (top right), and one of the ramekins (bottom center). We filled the ramekin with water, then poured it into the cereal bowl. It just filled it. Then we took the cereal bowl and poured it into the soup bowl. It just filled it.



So I guess the perception of size is just an illusion.