Which type of perceptual constancy explains the fact that a piece of charcoal is always black, whether you look at it in the light or in the shadow?

Perceptual constancy is the tendency to perceive something as having the same shape, size and brightness despite any changes that occur. The one involved with charcoal being perceived as black is brightness perceptual constnacy. This occurs because the black color has been embedded in our minds with relationship to charcoal, meaning regardless of the changes that occur to it, the charcoal will always be perceived as being black.