In recent years, people all across the country have formed laughter groups, in which a small number of people get together on a regular basis to laugh. They do not generate their laughter by watching funny movies or telling jokes. Instead, they simply laugh deliberately for some period of time. Even though the laughter is occurring without humor, people in these groups enjoy improved mental and physical health. The primary reason these groups lead to health improvements even though they do not change people's emotions is that