>If ELC is determining whether a ball is in or out, then ball marks should not be used as part of any decision-making process. For players, that requires erasing years of muscle memory not from their strokes, but from their brains, by ignoring not just the evidence right in front of them but the knowledge system that they have relied on to understand their sport.<p>It's always one of the issues where if you introduce technology folks now are playing the technology as it becomes the game. A little like Goodheart's Law, in a way...