I have peripheral vision incidents too. Sometimes, though, it's not just peripheral. Like once I was walking inside my house, and on the stairs I thought I saw a black shadow descending. It disappeared as quickly as I noticed it, so I don't know. A couple weeks ago, I was walking down my hall, and I saw a black shape floating through the foyer (we have a REALLY big house) and looked, saw it, but then it disappeared also. Recently I haven't seen anymore of those shapes and things, but there have been other instances.