Final answer:
The main idea of the passage is that one person's feelings can influence another person's feelings. It discusses the mirror neuron system and the facial feedback hypothesis to support this idea.
Step-by-step explanation:
The main idea of the passage "Is a bad mood contagious?" is that one person's feelings can positively or negatively influence another person's feelings. The passage discusses the mirror neuron system, which is involved in the spread of contagious yawning and emotions. It also presents research on the facial feedback hypothesis, which suggests that our facial expressions can affect our emotional experiences. Overall, the passage explores how emotions can be contagious and how individuals can influence each other's moods.