As I related in the first part of this book, my first breakthrough in understanding how people think differently occurred when I was a young father and had my kids tested by Dr. Sue Quinlan. I found the results remarkable, because she not only confirmed my own observations of the ways that their minds were working at the time but also predicted how they would develop in the future. I turned to her and others years later when I was trying to figure out the different thinking styles of my employees and colleagues.

At first, the experts gave me both bad and good advice. Many seemed as if they were more interested in making people feel good (or not feel bad) than they were at getting at the truth. Even more startling, I found that most psychologists didn’t know much about neuroscience and most neuroscientists didn’t know much about psychology— and both were reluctant to connect the physiological differences in people’s brains to the differences in their aptitudes and behaviors. But eventually I found Dr. Bob Eichinger, who opened the world of psychometric testing to me. Using Myers-Briggs and other assessments, we evolved a much clearer and more data-driven way of understanding our different types of thinking.

Our differences weren’t a product of poor communication; it was the other way around. Our different ways of thinking led to our poor communications.

From conversations with experts and my own observations, I learned that many of our mental differences are physiological. Just as our physical attributes determine the limits of what we are able to do physically—some people are tall and others are short, some muscular and others weak—our brains are innately different in ways that set the parameters of what we are able to do mentally. As with our bodies, some parts of our brains cannot be materially affected by external experience (in the same way that your skeleton isn’t changed much through working out), while other parts can be strengthened through exercise.

Once I understood that it’s all physiological, many things became clearer to me. While I used to get angry and frustrated at people because of the choices they made, I came to realize that they weren’t intentionally acting in a way that seemed counterproductive; they were just living out things as they saw them, based on how their brains worked. I also realized that as off-base as they seemed to me, they saw me the same way. The only sensible way of behaving with each other was to look down upon ourselves with mutual understanding so we could make objective sense of things. Not only did this make our disagreements less frustrating, it also allowed us to maximize our effectiveness.

Everyone is like a Lego set of attributes, with each piece reflecting the workings of a different part of their brain. All these pieces come together to determine what each person is like, and if you know what a person is like, you’ll have a pretty good idea of what you can expect from them.