If the eyes are fixed on the point in the midst of the angle, we might expect that this movement phenomenon would stop, but the opposite is the case.

The apparent movement from the vertical to the horizontal has to pass our fixation point and it seems that we ought now to recognize clearly that there is nothing between those two positions, that the intermediate phases of the movement are lacking; and yet the experiment shows that under these circumstances we frequently get the strongest impression of motion.

If we use two horizontal lines, the one above the other, we see, if the right time interval is chosen, that the upper one moves downward toward the lower.
But we can introduce there a very interesting variation.

If we make the lower line, which appears objectively after the upper one, more intense, the total impression is one which begins with the lower.

We see first the lower line moving toward the upper one which also approaches the lower; and then follows the second phase in which both appear to fall down to the position of the lower one.