Goosebumps — sometimes called goose flesh or goose pimples — are the little bumps on your skin at the base of hairs that spring up involuntarily whenever you get cold or experience strong emotions, like fear, pleasure or surprise. They also have a scientific name: kutis ansterina.
Getting goosebumps is a reflex, which is an action your body has automatically without you even thinking about it. This particular reflex is known as the pilomotor reflex. Humans aren’t the only mammals that have this reaction.
For example, when porcupines are threatened, their quills raise in a reflex action. Similarly, you may have seen a cat’s or a dog’s hairs stand on end when they sense danger or feel afraid.
When you get cold or 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 goosebumps.
They’re called goosebumps because, when you have them, your skin looks like the skin of a goose or a chicken whose feathers have been plucked out. So, if you want, you could call them chicken bumps, too!
The pilomotor reflex in animals often has the effect of making an animal look bigger. This might help to scare away potential enemies that may have caused the fear reaction in the first place.
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. Goosebumps also help to reduce heat loss, which helps the body warm up when it’s cold.