We usually consider willpower is a private thing and a subjective characteristic. However, this chapter tells me that I am wrong. We are not immune to the influence of others and we are dependent and may not have free will at all. Social influence can potentially damage our willpower. On the other hand, the contagiousness of willpower can also help us meet our willpower goals. I will list some of my thoughts about this chapter below.

—As the example of obesity epidemic is not detailed enough, readers may think the internal validity in this part is questionable. Obesity in a community or family may cause by other factors but not necessarily infection. For example, a new delicious fast food restaurant opened in this area may result in similar consequences.

—The most attractive concept I read this chapter is mirror-neurons. After I read the description about the function of mirror neurons, my intuition tells me mirror-neurons is the biology foundation of empathy. Based on Adam Smith’s A Theory of Moral Sentiment, empathy is the foundation of all moral codes and social collaboration. Mirror-neurons is probably the key to understanding human in both individual and collective level.

—Goal is also contagious. Catch other people’s goal will change our behavior significantly. However, it is a double edge sword as well. You can catch self-control as well as indulgence.

—Mutual respect and liking relationship is a powerful tool to convince or influence people instead of logical arguments.

—Internal incentives may not be as intense as external incentives but it is usually long-lasting. Religious communities and other social groups should take the responsibility to motivate people and change the society.

—We define “normal” based on our perception of the world, so if we want to change our behaviors we can start from changing our world view. How we view the world would be a good predictor of our behaviors. The example in this chapter is that the best predictor of whether a student cheat is whether he believes other students cheat, not the severity of penalties or whether he thinks he will be caught. This example reveals why environment can change people significantly.

—Pride and shame have a quick and direct influence over our behaviors, which Desteno calls this hot self-control. This kind of self-control is effective and powerful but it has limits as well. Once the deed is done, shame is more likely to inspire self-sabotage than self-control. The limitation of pride is that we must believe others are watching or others will aware what we have done afterward. In other word, people whose self-control rely too much on pride is very likely to lose control if they realize the absence of others.

—Any time we feel excluded or disrespected, we are at greater risk for giving in to our worst impulses.

The contagiousness of willpower is neither good nor bad. It is what it is.