Many believers say that even ordinary people can learn telekinesis by doing exercises that involve deep concentration. They often cite the Psi wheel experiment as proof. A Psi wheel is a device made of a small piece of paper shaped like a pyramid that balances on the tip of a pointed object such as a needle. One way to do the experiment is to sit a short distance from the Psi wheel, extend the hands toward the device, and concentrate intensely on it. The Psi wheel may start to spin. Believers in telekinesis say the movement is caused by waves of mental energy.