It is important to realize that McRaney calls these factors "cognitive biases." It is also important to realize the full title of the book: You are Not So Smart: Why You Have Too Many Friends on Facebook, Why Your Memory is Mostly Fiction, and 46 Other Ways You're Deluding Yourself.
McRaney admits that these factors or "cognitive biases" are actually "predictable patterns of thought or behavior" that lead people "to draw incorrect conclusions." McRaney also admits that we come "pre-loaded" with these biases. In fact, there are so many that humans do not even notice them. McRaney's best example of one of these factors has to do with confirmation. McRaney calls this factor "confirmation bias." In making decisions, McRaney says that people do research in order to find information to confirm their outlandish beliefs. At the same time, they ignore whatever they find that would prove their outlandish beliefs to be wrong. Any books found on a bookshelf or any bookmarks you have on your computer are the result of this. Another example McRaney gives of our functioning is the Wason Selection Task which involve people selecting one or more cards out of four. Without going into the vast number of specifics of this task, suffice to say that due to our "cognitive biases" most people choose only one of the cards in order to prove the rule while, in reality, it takes two cards to prove it.
Finally, it is important to realize the function of these factors. They help continue with "maintenance of a positive self-image." These factors that help influence your decisions are designed "to make you feel awesome about yourself." The unfortunate thing is that these "cognitive biases" are false.