Transformation Laws: Luminance Constancy

Luminance Constancy

As you read this page, processes are at work allowing you to make sense of it. How do you see the black ink on the page on a background of white (paper)? Many of these processes we take for granted. As light hits the page, it is reflected back to our retinas. These retinal images are simply shapes and gradations of light. The curves of the images on the page are then perceived as letters. The letters are strung together into words. As we take in these long strings of words, a message is received by our consciousness. This message is then converted into something meaningful within a specific psychological state. This visual system is complex. It follows steps that allow humans and other animals to navigate and cognize their environment.

Vision begins with light striking an object. The light is then reflected back to the perceiver. The amount of light striking an object can vary widely. Additionally, the amplitude and wavelength of light reflected back can vary as well. Light does not strike the distal stimulus in an even way. These variations would typically cause large variations the proximal stimulus, but they do not. The proximal stimulus is imprinted on the retina through a process called information registration. This information registration grossly underdetermines the distal stimulus. The information registered then passes through a sequence of psychological states via transformation laws. What determines what the final percept is a combination of registration and

transformation laws. Transformation laws are how the information is filtered. One such transformation law is called luminance constancy.

The ability of an object to reflect light in a certain way is called surface ...

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...ered. The retina itself doesn’t perceive anything. The retina merely registers the proximal stimulus and forwards the data on down the line. At the level of perception, our psychology filters and fills in the information gaps. Distance constancies allow us to rightly say that people in the distance aren’t an inch tall. Luminance constancy allows us to see the relative brightness of an object regardless of environmental changes. It is our ability to perceive a fixed luminance correctly regardless of illumination. This allows for representation and reference to be accurate. It is representation, not information registration, which is informed by our psychology. Perceptual constancy allows our representational states to be true or accurate.

Works Cited

Tyler Burge, Origins of Objectivity, Oxford University Press, 2010