The reason why this happens is because the way your brain senses direction and whether or not you’re right-side-up is by fluid in your cochlea. The fluid tingles tiny little hairs that send messages to your brain, which interprets them to find direction. When you spin, the fluid spins with you and keeps spinning when you stop, confusing your brain and making you dizzy. Spinning the other way slows and then stops the fluid spinning, causing the dizziness to stop.