In short

Learn to increase the effectiveness, conversion rates, and usability of your own design projects by finding the answers to questions such as:

What grabs and holds attention on a page or screen?
What makes memories stick?
What is the more important, peripheral or central vision?
How can you predict the types of errors that people will make?
What is the limit to someone's social circle?
How do you motivate people to continue on to the next step?
What line length for text is best?
Are some fonts better than others?

These are just a few of the questions that the book answers in its deep-dive exploration of what makes people tick.