Fun with Retinal Burns

Disclaimer: Don’t look at any bright light source. It may damage your eyes!

The sound of a fly buzzing meant  one more thing for me to before going to bed. What happened next took me by surprise and provided some fascinating entertainment that I thought I’d share with you.

Returning from the kitchen with a can of fly spray, I heard it’s intended target was in the last remaining light source in my house - the big orange lampshade by the couch. After peering down into the lampshade and releasing a couple of light sprays I returned to the darkened kitchen only to notice I was seeing spots, three large overlapping ones to be precise.

These black Venn Diagrammesque apparitions were due to photobleaching of the chemicals my eyes use to sense light. They were in three distinct places because the eye flicks quickly when scanning - if I had been watching a marble race I’m sure it would have been a circle.

Anyway, we’ve all see spots right? What was really neat was what I discovered next…

Covering my eye made the spots go a light colour. Looking at the pantry doors resulting in them being dark. The spots faded within seconds however covering my eyes brought them back, as did shifting my gaze to a different area in the room. I think I’ve found a new way to demonstrate perceptual filling-in. Until now I’ve only heard of blind spot fill-in.

The beauty of retinal burn fill-in is that you don’t need to find your blind spot, or be a certain distance from things as you can control where you place the burn. It’s amazing to watch the burn dissolve as the brain fills in the missing information. I’d advise against deliberately looking into any bright light source but next time it happens I suggest you use the opportunity to experience first hand the difference between the signals your eyes send and what you perceive.