Not seeing it with this image, but I know exactly what you're talking about as I've had it happen before. On backgrounds like that bright red, the foreground seems to be floating above it and moving independently from the background, right? I've been told this is a symptom of astigmatism (and now that I think about it, the effect probably went away when I had my lasik a decade ago)
The more I look at it I think it's attached to the chair to help him stand. Note that it's the only chair visible. He had suffered from peripheral neuropathy for years and had very restricted mobility and probably couldn't stand for long periods by then.