On shadow ghosts

Looking out of a window recently at a familiar scene I noticed a black cat. As it was not something I often see I turned to look at it more closely only for it to vanish as I was watching! So, a ghost then!

Instead of the cat I saw a dark cat-shaped shadow on some long grass. It was the right size and shape for a cat and undoubtedly what I’d seen. Notice I said ‘turned to look’. When I originally saw the ‘cat’ it was in my peripheral vision. It was a peripheral vision misperception. Nevertheless, it looked very real, as misperceptions do. The ‘cat’ was noticeably darker than the shadow in the grass.  I think this is because the rod cells in our eyes, that dominate peripheral vision, are not sensitive to colour.

It is interesting that most reports of shadow ghosts  are of dark figures seen in peripheral vision. When the witness turns to look at them they vanish. Rather like my black cat! In my opinion, most reports of shadow ghosts in peripheral vision are misperception. So why don’t witnesses notice the real object being misperceived, like the shadow on the grass, when they turn to look at the ghost? I think it’s because the object is not as dark or obvious when in central vision and in colour, like the shadow in the grass. It is no longer a black shape but perhaps just an object, or shadow, that happens to vaguely resemble a human figure. In addition, the rods in our peripheral vision are more sensitive to light and so can pick out things that don't stand out in central vision. It’s also possible that the real object may have left the scene. The rods are also more sensitive to movement and changes in a scene. So a moving object seen only in  peripheral vision will attract more attention. The ghost might certainly be something moving, just not a human figure. Peripheral vision is low of visual detail, because there are fewer cells compared to central vision. So something just vaguely resembling a figure could easily be misperceived as a shadow ghost.