Unsophisticated is an adjective that applies to a person who is thought to lack worldly wisdom, who is not urbane, who is not experienced in, or knowledgeable about, prevailing customs and manners of living and thinking. Artless implies something of the meaning of unsophisticated but suggests a lack of guile or artificiality that results from unconcern about the reactions of other people. That is, an unsophisticated person lacks wisdom and experience in certain areas; an artless person has the same lacks but doesn't care because he is free from any desire to impress others. See also ingenious.
Dictionary of problem words and expressions. Harry Shaw. 1975.