Can One Evaluate the Effects of Meditation?

I have been doing compassion meditation for a bit (about 13h of sitting meditation). I think perhaps I haven't meditated *enough* to see benefits, but I wonder: **When beginning, is it possible to *have* benefits, but not *see* them? In other words, that one's behaviour or attitude changes despite no conscious awareness of this?** Is sitting practice at the beginning less fruitful but still establishes the basis for (in this case) compassionate attitude?