Taking that to the next level involves the addition of pantomiming. With my eyes either open or closed, I let my mind visualize the motions—the movement of my arm, the flex of the rod, the unrolling of the line. I find that the visual-tactile interplay becomes stronger here than when using pure visualization alone.
I also employ visualization during actual casting. This involves closing my eyes, trying to further develop and understand subtle tactile cues that the line and rod are passing on to me. During these times, I may visualize my casting so that my mind has something to follow when my eyes are seeing only black. Of course, I don’t spend an entire practice session in the dark; I typically alternate between eyes-closed casting and carefully watching my cast. That way I can better cross-reference the visual with the tactile in terms of timing.
Sound can also be a surprisingly useful contributor to the overall educational experience. The sonic signature of a cast can serve as a clue that all is going well (or not). Many casting instructors (myself included) will talk about listening for a certain sound as a cast is being made. In fact, I like the newer generation of textured fly lines for teaching for that very reason. I find the ziiing of the line in the guides provides additional, useful feedback, particularly when assessing skills like hauling.
*See that photo up there? It's not real. It's me visualizing a cast and then projecting it here on Sexyloops. I should have visualized a tighter loop, i guess....