After reading the reviews, I decided to take a chance and buy an inexpensive used version of this book just in case that it brings no benefits like many here claim. I'm glad now that I made that decision. The book gives very little support for its claims, and in fact spends much time discussing the history of memory more than actual supporting studies. The techniques are not detailed very well and often are difficult to understand fully. They give techniques for many off-topic subjects, such as waking up without an alarm clock. They don't tell where they get the sources for their information. The actual names of the authors of this book aren't even listed. Despite these flaws, I put my faith into these techniques. I used them for over a period of 3 months, with absolutely no improvement in my memory at all. I finally gave up, knowing this book was claiming something that was false.