The two places lit in both pictures. In the top row they never go dark; in the bottom row they blink off with the rest.
Tricks of motion
Ternus illusion
In each row, do all the dots move together, or does one dot jump from one end to the other?
In the top row one dot jumps from end to end; in the bottom row all three move together. Both rows show the same two pictures: only the blank between them differs.
Why? Your brain picks the simplest story for what it saw. With no blank, the middle two dots never go dark, so they look still and only the end one moves. With a blank, everything vanishes and comes back, so the simplest story is that the whole row moved.
Picture: Drawn by Science Playground · Wikipedia(opens in a new tab)