Which look bigger, packages of complicated shape or packages of simple shape? Some prior research shows that complex packages appear larger than simple packages of equal volume, while other research has shown the opposite -- that simple packages look bigger than the more complex. US researchers, writing in the International Journal of Management Practice believe they have resolved this dilemma. Lawrence Garber of Elon University in North Carolina and Eva Hyatt and Ünal Boya of Appalachian State University report that human beings are just not very good at estimating the size of objects, meaning that it is often size appearance and not actual size that affects things like consumer choice. And it is aspects such as package shape and the number of packages viewed all at once that contribute to this error. The team asked volunteers to estimate the relative volumes of sets of packages whose shapes are simple or complex, presented in groups of between two and sixteen packages.

The results of this experiment demonstrate that presentation context affects a person's impression of size much more than was previously thought. "When packages are displayed in sets of nine or more, packages of simple shape appear larger than packages of complex shape," the team reports. "But, when packages are presented in sets of eight or fewer, complex packages appear larger than simple packages."

Garber and colleagues suggest that this reversal of perception means that how we estimate the volume of a given package is affected markedly by whether or not other packages are in the same "visual tableau（画面）." Moreover, the way we estimate volume of packages is flipped when the complexity of such a tableau leads to cognitive overload.

"One implication of this finding is that a package that appears smaller than another when the two are viewed sitting on a crowded store shelf, may actually appear bigger when the two are picked up and held in a consumer's hands," Garber says.