Chapter 3 is titled: Biological Psychology. It covers the basics of the brain and nervous system. Big topics in this chapter include neurons, neurotransmitters, the central nervous system, brain imaging, and a bit on nature versus nurture. I found the stuff about neuroscience to be the most interesting in this chapter. There is a large diagram of a neuron that I think looks very cool, and descriptions are given of many different neurotransmitters. Other interesting things in this chapter include phrenology, an early attempt at mapping the mind onto the brain based on bumps on the skull, and a picture of a dead salmon supposedly showing brain activity.