Some shamans encourage the belief that they possess supernatural qualities which transcend human nature. To wit, shamans are usually credited with the ability to speak to spirits and perform feats of magic such as astral projection and healing. Shamans are usually found in tribal cultures with nature religions and beliefs in ancestor spirits, though some persons in modern Western Cultures also consider themselves to be shamans. The shaman's office is usually held to be hereditary and his chief assistants are held to be his ancestral spirits.
One of a shaman's main functions is to protect individuals from hostile supernatural influences. He or she deals with both good and bad spirits, performs sacrifices and procures oracles. Shamanistic traditions often include induction of trance through drugs (often neurotoxins known to be hallucinogens), chanting, fasting, dancing and music. The drum (tungur in Altaic) is an important instrument in shamanistic ceremonies, which may be used to induce autohypnotic phenomena. Researchers also suspect that in some cultures schizophrenia or similar conditions may predispose an individual to the role of shaman.