# 49. Manipulation of bias and heuristics in decision making ## 49.5. Methodology/Refinements/Sub-species ### 49.5.15. Decoy effect This is a change of preferences where a third option is asymmetrically dominated. A manipulator introduces an inferior option to lead the victim to one of the more dominant options. This is a favourite trick in sales and marketing. For example, if there are 2 models of a hard disk available, of different sizes and prices, some customers will go for size, some for price. If a third model then is introduced which is less good value than either and has a size in between that of the original two models, most customers will ignore the decoy (obviously) and tend to buy the more expensive, larger capacity model from the original options.