Chapter three focused on the biological aspect of psychology. The key points that were covered were nerve cells, the brain and its use, the endocrine system, and genetics. These things all combine together to make the body function and help us go about our lives.
The thing that I found most interesting in this chapter is a section called "How Much of Our Brain Do We Use?" This section discussed the common myth in psychology that we only use 10% of our brain. A movie called "Limitless" came out in recent years supporting this myth despite it being false. The truth is that we use just about all of our brain capacity. Each part of the brain serves a purpose to help us function. If we were only to have access to 10% of our brain, than many of those purposes would not be fulfilled. The authors discuss that even if a small area of the brain is damaged, we might lose complete function from that area. So if each person was only using 10% of their brain, than the way we function would be completely different and probably result in our body not being able to function.