These three areas — the domain, the eye/brain, and the implementation — intertwine with each other. A single element may have conflicts in one area or all three at the same time. Much of the work designing interfaces involves teasing apart these conflicts in order to solve the right problem. Is the action correct, but it’s too hard to find? That’s a conflict with the eye/brain. Is the screen clear and simple but it doesn’t show the right information? That’s a conflict with the domain. Does it take too long to get feedback from a common action? That might be an implementation problem.