Models of consumer decision making often condition on attention to the different offers or alternatives to choose from. However, in many environments offers not only compete through their utility but also for the attention of decision makers. In this case, it is important to distinguish between attention and utility - it makes a difference whether an offering is overlooked, or rejected conditional on awareness - for optimal marketing control and empirical measures of competition. We show how quantity choices, in contrast to multinomial choices, facilitate the empirical distinction between attention and utility. In our illustrative application we analyze choices from simulated store shelves. We find that the number of facings of a brand on the shelf influence attention but not utility from the brand. We then formulate a parametric model that identifies attention based considerations sets. We find overwhelming support for this model compared to a model that ignores attention and motivates choices from utility only.