I understand that goosebumps are stimulated by fear and cold in order to trap air between hair to keep us warm and make us look more intimidating. Of course today this trait is useless due to technology and ordered civilization. So adrenaline causes arrector pili muscle to contract and there fore causing the hair to point upwards. All this happens due to fear or cold. But i do not understand why we get goosebumps when we get excited when an innovative idea pops in your mind. Is there anything else that can trigger adrenaline?