Using the Golden Ratio to boost sales

As part of my research into the psychology of design I've borrowed a book from the library (actually lots of books, but the one I'm looking at currently is) 'Guerilla Marketing Revolution', Levinson, J.C., Hanley, P. R. J., 2006.

One part of their book examines the Golden Ratio (1:1.618) which has been used throughout art and design history to render artworks more pleasing on the eye. Levinson and Hanley take this step even further by stating that design which is based on the golden ratio is so pleasing on the eye that "materials which used the golden ratio performed five or six times better than those that did not" (p.80).

Furthermore they find that it improves readability and data retention but they state that the horizontal ratio has the only benefit in sales and marketing literature while vertical lines can be used in website design.

I also always use a Golden Ratio grid on business card layouts.