I don't see how you would not pee while taking a dump... unless you do like Spector and waste an egregious amount of water. The two actions are controlled by the same muscle (lazy ass/efficient evolution).

On a tangential note, given I can only imagine Spector's method being used to avoid pee-splash, have you guys ever considered the physics problem behind optimal splash avoidance? Obviously this is hypothetical, but pooping from a greater height maximizes distance but also splashback, while pooping at close water-range has the opposite effect. I suppose what you'd want to do is write (or google) an equation that solves for the volume of water splashed onto the ass as a function of height and then differentiate it for minimization. Of course, this neglects other variables such as density and shape of the poop, but I guess you could consider a generalized model only.

I don't read on the toilet.