Read the working paper
INSEAD Working Paper 2013/45/MKT
With rising public concerns about waste and overconsumption, predicting and effectively managing consumers’ package size impressions have become critical for both marketers and public health advocates. The AddChange heuristic model of size impression assumes that people add (instead of multiplying) the percentage changes in the height, width, and length of objects to compute their volume. This simple deterministic model does not require any data to accurately predict consumers’ perceptions of product downsizing and supersizing when one, two, or all three dimensions change proportionately. It also explains why consumers perceive size reductions accurately when only one dimension of the package is reduced, but completely fail to notice up to a 24% downsizing when the product is elongated in the manner specified by the model, even when they pay close attention or weigh the product by hand. The model can be used to determine the dimensions of packages that create accurate size perceptions or that increase consumers’ acceptance of downsizing.