You might find the work of Benjamin Libet to be interesting (sorry it's Wiki, but actually not bad articles!):
When you scratch an itchy nose, the volition to move comes from a different part of the brain, a different brain function, than the conscious mind. The conscious mind catches on after the command to scratch has been fired off, but the micro-second timing of it is so fast that we "think" that we consciously made the decision.
When working on IP and aiki, a person actively -and with awareness- activates and manipulates that volitional, non-conscious brain function to activate the processes necessary to generate IP and effect aiki.
Some people suggest that it's mental imagery allowing us to fire off actions, but that's really an extra step, one step removed from the intent/volition itself.