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Container Size and Visual Bias

Can you tell the difference in container size between a Haagen Dazs (14oz) and Ben and Jerry's (16oz)?

Two researchers, Chandon and Ordabayeva, conducted experiments on customer perceptions of package size and changes, concluding “that changes in size appear smaller when products change in all three dimensions (height, width, and length) than when they change in only one dimension.”

More specifically, “In particular, our results show that consumers demand lower unit prices for larger packages not just because of diminishing marginal utility or storage costs but because they underestimate the actual increase in product quantity provided by larger packages. Finally, we show that providing objective volume information improves the accuracy of size estimations but does not reduce the effects of dimensionality. In contrast, we find that changing product sizes in 1D encourages downsizing and reduces the overdosing of alcohol and infant medicine, which may have important implications for policy makers.”


Understanding consumer response to product supersizing and downsizing is an important issue for policy makers, consumer researchers and marketers. In three laboratory experiments the authors found that changes in size appear smaller when products change in all three dimensions (height, width, and length) than when they change in only one dimension. Specifically, they showed that a) size estimations follow an inelastic power function of the actual size of the products; b) size estimations are even less elastic when size changes in 3D than when it changes in 1D; and c) the effect of dimensionality is not reduced by making size information available. As a result, consumers expect (and marketers offer) steeper quantity discounts when packages and portions are supersized in 3D than when they are supersized in 1D; consumers pour more product into and out of conical containers (in which volume changes in 3D) than cylindrical containers (in which volume changes in 1D); and consumers are more likely to supersize and less likely to downsize when package and portion sizes change in 1D than when they change in 3D.

Source: Chandon, Pierre and Ordabayeva, Nailya, Downsize in 3D, Supersize in 1D: Effects of the Dimensionality of Package and Portion Size Changes on Size Estimations, Consumption, and Quantity Discount Expectations (July 17, 2008)