Much of the attention research I describe here and in the book is based on the work of Dr. Robert Heath (among others) who happens to be at the University of Bath in the U.K. I link to some of these sources in the article. Check out his research and books if you want to dig deeper into these topics. I tried very hard to make sure all the science I build upon is sound, with numerous peer-reviewed studies backing it up. For the sake of keeping this article brief, it’s not all here, but that’s what the book is for.