mechanism of this kind of illusions is still not well understood...
My hypothesis is that it is induced by the alternating
of small light and dark strokes. It is a kind of afterimage
effect caused by the lateral
inhibition of our retina.
The eye actually tends
to shift around the stroke patterns by avoiding to focus
on the disturbing single elements; but doing that, each consecutive
retinal image is then superimposed with a very small delay
so that a light visual 'swarming' activity appears at the
boundaries of the stroke patterns (within the color curved
'neons'). The effect decreases, or even disappears, if you
bring your face closer to the screen.
This illusion is similar to Isia Leviant's
illusion named Enigma.
encouraged to expand and/or improve this article. Send
your comments, feedback or suggestions to Gianni
A. Sarcone. Thanks!