Recently (the last year or so), I started doing something different when effectively applying a technique. I would get an image in my head of how the technique should feel - mostly as some sort of flowing line, combined with sensations along parts of the line. Depending on the technique, there might be loops, a fulcrum or two, or branching or steps.
It's very weird, but whenever I do the technique with that image in mind, it almost always works exactly as it should. Now, when I am learning techniques, I try and work out what its image should be, and I find that doing so allows me to pick it up quicker - If an image looks forced or doesn't hang together, I tend to find that I'm doing the technique wrong.
Mental imaging as a way of helping to understand and guide the body through a technique is something I have seen mostly mentioned with regard to kata practise, where one is often exhorted to imagine they are being attacked by opponents, and to work out how the movements of the kata might be a response to those attacks. This imagining is something I have indulged in for years, almost from the moment of starting karate, and indeed I have found that running through a kata/technique or two in real-time in my mind before going to sleep helps me to improve my ability in doing that kata or technique the next time I actually do it. It doesn't beat the real thing, but I find that it allows me to nut out problems I have, and use time that isn't normally available, for training.
But this whole imaging thing is new to me; it wasn't a conscious decision on my part to do it, it's just something that my brain has thrown up of its own accord. I'm interested to see what it comes up with next.