Backpack in overhead bin

I check a bag and I travel with a backpack. No rollaboard, so my backpack goes in the overhead bin, not in front of me. I get it, if someone travels with a rollaboard AND a backpack (or purse or whatever the personal item is), the rollaboard goes up, personal item goes underneath the seat in front of them. My one item - my backpack - is going in the overhead bin.