In animals covered with fur or hair, the erect hairs trap air to create a layer of insulation. Goose bumps can also be a response to anger or fear: the erect hairs make the animal appear larger, in order to intimidate enemies. This can be observed in the intimidation displays of chimpanzees, some New World monkeys like the cotton-top tamarin, in stressed mice and rats, and in frightened cats.

In humans