9 points
8 points
In 5th edition you are not supposed to know; this is what the Passive Perception score is for. If you’re not specifically looking for anything, the DM is supposed to use your Passive Perception instead of rolling a check that would alert you to the existence of something hidden; if you are specifically looking, you roll Perception whether or not there is anything to find.
4 points
5 points
2 points
1 point