I read a study similar to this in one of my Pyschology courses in college. They did studies where there were 3 different variations; urinals with a urinal cake, a urinal cake with a picture on it, and no urinal cake.
They found that the picture was inconclusive, i.e. it didn't matter what it was. They also found that not only will the urinal with the picture have less "splash" but they went through a lot more cakes, it kept the urinal cleaner, and "the delay of onset" of urination was much less, and men finished urinating much sooner.