I occasionally have hallucinations in my peripheral vision. It's usually just an instant. Long enough to see it and its details, but short enough to make me doubt it was there. I have heard of other people having this type of hallucination.

Today, I was cutting grass on my tractor. It has a roll bar. When I'm on it, I occasionally see it out of the corner of my eye. Today, I turned my head a little and very definitely saw a man wearing shorts and a headband. I turned my head a little more and it was just my roll bar.

Are these even real hallucinations, or are they just tricks of my peripheral vision?