Search up Herman Grid Illusion for the picture and submit that.
Explanation.
Where the white lines intersect in the middle are surrounded by more white on all sides than any other point along the white line segments. Your retinal ganglion cells notice that there is more white around where they meet because they are organized to increase contrast with lateral inhibition. Better contrast makes it easier on our eyes to see the edge of something. Your retinal ganglion cells don’t respond as much at the intersections because there is more lateral inhibition for more white spots nearby, compared to the lines which are surrounded with black.
Simpler explanation:
White lines cross across a black background. Where the lines cross, there is a higher contrast. Your retinal ganglion cells notice that there is more white around where they meet, making them not respond as much at the intersections. There is more lateral inhibition, where neurons response to stimulus is restrained by the activity of nearby excited neurons, for more white spots nearby.
Hope this helps!