I rode my horse in an outdoor arena last night. It is lit by high pressure sodium vapor flood lights. This set up a fun ride. My horse and I would pass under one of these lights at far end of the ring. The light would go out as we passed under it and it would come back on as we rode away from it. We tried this at a walk, then trot, canter and gallop. We came at it in a pattern, then circles, then at random. We did it at varied times to make sure it wasn't happening at regularly timed intervals. It was just happening when we approached the light or we were under it. It was strange, intriguing and fun.
This has happened under the arena lights before, but in the more typically random and unpredictable way, as most of the SLIder phenomena usually do.
Here was the first time I was able to SLIde in any predictable fashion.
Is it possible my horse is a SLIder too?