The science of shopping - I did not know there was such a field of study.
I think every retailer who reads this book will be glad that Paco Underhill decided to study shoppers and put his years of findings in book form. The author uses his hours and hours of watching shoppers to give advise on such things as store layout, use of floor space, what draws customers in and why they don't buy.
For example, Underhill was observing a women's dress department during the morning hours. A woman came in to shop pushing her child in a stroller. The racks were not spaced far enough apart for the stroller to fit through easily.
Of course, she was not going to leave her child alone in the isle. Instead, she left the store without making a purchase, feeling annoyed.