The claim that certain individuals lack an inner monologue is a testament to this—I can't imagine what that would be like but that is certainly nothing like my conscious experience is. To me, the lack of an inner monologue sounds very much like the 'dark universe' in which the brain is doing all of the processing and there is no conscious observer to witness the unfolding. I'm sure people without a inner monologue are still conscious.. but—it's interesting to think about how different their experience may be like.