"Paco Underhill" is an environmental psychologist, the author of the books Why We Buy: The Science of Shopping, Call of the Mall: The Geography of Shopping, and What Women Want: The Global Marketplace Turns Female Friendly, and the founder of a market research and consulting company called Envirosell. He employs the basic idea of environmental psychology, that our surroundings influence our behavior, to find ways of structuring man-made environments to make them conducive to retail purposes.

More Paco Underhill on Wikipedia.