Fast and frugal shopping challenge.

There are a number of mobile shopping aids and recommender systems available, but none can be easily used for a weekly shop at a local supermarket. We present a minimal, mobile and fully functional lambent display that clips onto any shopping trolley handle, intended to nudge people when choosing what to buy. It provides salient information about the food miles for various scanned food items represented by varying lengths of lit LEDs on the handle and a changing emoticon comparing the average miles of all the products in the trolley against a social norm. A fast and frugal shopping challenge is presented, in the style of a humorous reality TV show, where the pros and cons of using various devices to help make purchase decisions are demonstrated by shoppers in a grocery store.