Interior monologue

Interior monologue is the technique of presenting a character's thoughts from inside: inner speech rendered directly on the page. The article's distinction, citing the Oxford Dictionary of Literary Terms: the two terms are often used interchangeably, but psychologically "stream of consciousness is the subject matter, while interior monologue is the technique for presenting it." The literary difference is discipline: interior monologue always presents a character's thoughts "directly", but "does not necessarily mingle them with impressions and perceptions", "nor does it necessarily violate the norms of grammar, or logic"; stream of consciousness "also does one or both of these things." The article credits Arthur Schnitzler's "Leutnant Gustl" (1900) as an early full use of the technique.

For a novelist the choice is reach: interior monologue keeps interiority readable at length, where sustained stream of consciousness taxes the reader, and the third-person technique that blends the character's voice into the narration is free indirect discourse. The spoken cousin is the monologue.