Single data point but: I can alternate between inner monologue (heard [in somebody else's voice not mine(!)]) and no monologue (mainly social activity - say stuff then catch myself saying it and keep going) - stuff just happens. When inner monologue is present it seems I'm in real time constructing what I imagine the future to be and then adapt to that. I can feel as if my body moved without moving it, but don't use it for thinking (mainly kinesthethic imagination or whatever). I can force myself to see images, and, at the fringe, close to sleep, can make up symphonies in my mind, but don't use them to think.