Nervous systems can be studied in isolation or in groups. It's harder to do that in the laboratory, although there are people starting to put two people into a scanner and seeing how the brain areas interact. The other thing is this notion of social contagion and we are profoundly influenced by sensory experience. Some people are drawn more toward or are shifted more by other people's emotional states. We sometimes hold up empathy as this ideal. That empathy is very dangerous because empathy in the wrong context,. You know, your kid freaking out about an experience at school. If you experience true empathy, you abandon your own emotional state, but you're not effective parenting or effective leadership.