system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: Why do people get chills whenever they see/experience something that creates a strong emotion?
gpt
When you experience a strong emotion, your brain sends signals to your muscles that make them tense up. When the muscles in your skin that are attached to hairs do this, they make the hairs stand up and pull your skin up just a bit, creating goose bumps (or chills). This so-called "pilomotor reflex" in animals often has the effect of making an animal look bigger. This might help to scare away potential enemies. In humans, though, the reflex has more to do with muscles. As the body reacts to fear, for example, it will often prepare either to flee or to fight the danger. This requires muscles to tense and be ready. The reflex helps to get the muscles warmed up and ready to move.