psychology of the order in witch players do tasks based on dificulty

does anyone know how consistently people will do an easier task first?

in a level of a game I am making, there are two challenges; and easier one and a harder one.

in this level, I introduce a mechanic. the only thing you have to know about it is that in this situation it requires you to do the harder thing first, and it's function cannot be communicated via the visuals easily, only through player interaction.

what I want to happen is that the player does the easier task first, thus finding out how the new mechanic works and realizing that they have to do it second, then they restart the level, and do it in the right order.

so, in conclusion, I want to know whether I can rely on the player doing the easier thing first, and what other ways I can influence which they start with other than difficulty