Mark Wyner Won’t Comply 
These cubes aren’t moving or changing (as implied by the arrows). At all. Not even a little. Other than the color toggle, they remain constant.
(Credit: Ja Gari Kin)
EDIT: added content warning because of the flashing.
Nick Piegari@markwyner they kinda do though
Kim@nicksmadscience @markwyner it is the way the lines transition from black to white that appears to alter. Not the position of each line itself. The arrows only add to the suggested movement
Bornach@Ex_spurt @nicksmadscience @markwyner
The phi motion illusion is explained in more detail here
https://jake.vision/blog/motion-illusions/
Includes other examples where the illusory motion cues are not in opposing directions and don't include arrows