Goose Bumps Most people have experienced goose bumps. It is an involuntary reflex called the pilomotor reflex. Tiny muscles beneath the skin contract and pull our hair to an upright position. This is how we get goose bumps. They occur anywhere that we have hair on our body, but the most common places are our arms and legs. This reflex is a natural reaction to feelings like fear, cold, happiness. Animals experience the pilomotor reflex too. For example, when a cat is frightened by an enemy, the cat's hair will stand on end. It makes the cat look bigger and it may scare away the enemy. The pilomotor reflex can also help animals to stay warm. Many scientists think that the pilomotor reflex is useless for people. It doesn't keep us very warm (although it does prevent some heat from leaving the body), and it doesn't make us look bigger.