Dotted line illusion. Hiro Ito and Stuart Anstis.

In Fig 1, move the cursor to the left along the arrow and track it with your eyes.
The V-shaped lines appear to move inwards, since they really do approach the fovea.
Do the same in Fig 2 -- and the dotted lines appear to move OUTWARDS, not inwards!
Reason: Fig 3a: The rightward motion of a simple black line can be decomposed into 2 vectors,
along and across the line. The vector along the line is not seen (Fig. 3b), so the line is perceived
as moving at right angles to its own length. The rightward motion of a dotted line comprises
the same two vectors (Fig. 3c). However, the black/white CONTRAST along the line is much stronger
than the black/gray or white/gray contrast across the line. So now the vector along the line
is perceptually weighted more than the vector across the line.