I let my cats explore my desk as they wish, except when they step on a keyboard or something. Then I gently grab them and pull them away. This has lead to a situation where they now know not to step on them, and are pretty good at avoiding stepping on things... unless they want my attention. Then they will systematically go through every steppable thing until they find the one that makes the most noise and keep doing it until I stop what I'm doing. They know. There's no other explanation. I refuse to believe anything else.