Jesus Christ- Optical illusion.

[MnM]

I think when it's bright the retinal cells will eventually become less sensitive and vice-versa (they adapt too, not only the pupil). Thus, when you focus of the dots, some of the cells receive the white color (which is bright, so they become less sensitive), and some of them receive the black color (so they becomes more sensitive). Then, when you look to another place, the cells that saw the white color will see darker colors because they are now less sensitive, while the cells that saw the black color will see brighter colors because they are now more sensitive.

it happens when you move from dark place to a bright place, since your eyes have become sensitive to light, it seems brighter than it usually is

Thank you so much, it makes more sense now.

the white thing acts as if it is hair

Not in most of the case. It also describes the nose and some part of eyes.