A cultural model is a cognitive schema that is intersubjectively shared by a social group. Such models typically consist of a small number of conceptual objects and their relations to each other. For example, Rumelhart (1980), following Fillmore (1977), describes the schema – and cultural model – of buying something as made up of the purchaser, the seller, the merchandise, the price, the sale, and the money. There are several relationships among these parts; there is the interaction between the purchaser and the seller, which involves the communication to the buyer of the price, perhaps bargaining, the offer to buy, the acceptance of sale, the transfer of ownership of the merchandise and the money, and so on. This model is needed to understand not just buying, but also such cultural activities and institutions as lending, renting, leasing, gypping, salesmanship, profit making, stores, ads, and so on. Cognitive schemas tend to be composed of a small number of objects – at most seven plus or minus two – because of the constraints of human short-term memory (Miller 1956; Wallace 1961). For example, to judge if some event is an instance of “buying” something, the person making the judgment must decide whether there has been a purchaser, seller, some merchandise with a price, an offer, and an acceptance, along with the appropriate transfer. Since all these criteria must be held in mind simultaneously to make this judgment with any rapidity, the criteria cannot exceed the limits of short-term memory.