If an artist was working without artistic training, creating paintings inspired by his or her dreams, we would call this person a/an , or outsider, artist.

If an artist was working without artistic training, creating paintings inspired by his or her dreams, we would call this person a naïve art maker, or outsider, artist.

Explanation:

For the most part, naïve art maker, or outsiders are self-taught artists, painters and sculptors without any formal art education. It is even symptomatic that most of them, with rare exceptions, are accompanied by almost low general and fine arts education, which certainly does not preclude their natural intelligence and artistic inspiration. Many of them have proven that general education, even fine arts, is not a prerequisite for reaching the world's top art and achieving a high artistic level.