White's Illusion - Belongingness

Belongingness

Our perception of an area's lightness is influenced by the part of the surroundings to which the area appears to belong.

In the disc example (Fig. 3), the four discs on the left are identical to the four discs on the right in terms of how much light is reflected from the discs, that is to say, they are physically identical. The theory to explain the different psychological experiences is called belongingness.

The discs on the left appear dark and the ones on the right appear light, this is because of the two displays. In the display on the left, the dark area on the left seemingly belongs to the discs, and the discs are obscured by the light mist. On the right side, the same dark areas are interpreted as belonging to the dark mist. In the meanwhile, the white parts are seen as the color of the discs. Therefore, our perception of the lightness of the discs is significantly influenced by the display, which is the mist in this case (Anderson & Winawer, 2005).

We can use the belongingness theory to explain White's illusion. According to belongingness theory, the lightness of rectangle A is influenced by the white display, which should be the white bars that surround it. Similarly, the rectangle B on the right side is surrounded by the dark bars, and the lightness of rectangle B is affected by the dark background. As a result, area A which rests on the white background appears darker than area B which rests on the dark background.(Alan Gilchrist et al. 1999)

However, the limitation of belongingness theory is that, firstly, it only explains why rectangle A looks darker than rectangle B, but what we want to know is why the gray areas on rectangle A look darker than in rectangle B; secondly, when talking about the background, Belongingness theory appears quite the same as simultaneous contrast theory, they just use different names.