Talk:Barberpole illusion

From Wikipedia, the free encyclopedia

[edit] "Real" motion

who said it was "obvious" when in a round shape? I saw the lines advencing in a diagonal manner (top-left to bottom-right). There is no way to define the "real" movement here (left to right, top to bottom and top-left to bottom-right movements will give exactly the same pixels over time, whatever the shape of the window). Anon

This isn't a great animation. Its a bit too slow to create a compelling effect. Also, I moved the circular aperture figure to the left so it isn't colinear with the 'pole' version above. The two figures are probably being grouped so the motion appears the same. As for your comment that there is no way to define the "real" motion... welcome to the wonderful world of visual perception! Famousdog 13:39, 28 May 2007 (UTC)

The world of visual perception may be wonderful, but the quoted sentence is still incorrect. Even if we assume that the "real" motion is horizontal, a person looking at the image can see either horizontal, vertical or diagonal movement, whichever he chooses (and I believe the diagonal is the most natural). So the horizontal motion is far from being obvious. -- Meni Rosenfeld (talk) 23:33, 11 July 2007 (UTC)

Extensive re-write. Hope that's clearer. The "horizontal motion" alluded to was the physical direction of spin in a real barberpole, not the perceived direction. The confusion is a result of the fact is that there is no "real" or "true" motion. The physical motion of a spinning pole is not remotely what we perceive. Famousdog 14:02, 12 July 2007 (UTC)

Much better, thanks. I've made some additional modifications. -- Meni Rosenfeld (talk) 14:40, 12 July 2007 (UTC)