Light bends as it passes through substances of different densities, a process known as

As your lens hardens through aging, you may have trouble with

The image projected on the retina is

Full dark adaptation, such as going from constant light to sudden darkness when turning out one's bedroom lights, takes about _____ minutes.

Cones are the special cells responsible for

In opponent-process theory, there are _____ primary colors.

Mateo has trouble seeing colors because the cones in his eyes do not work properly. When Mateo does see color, he sees primarily in blues, yellows, and shades of gray and confuses reds and greens. Mateo suffers from

The three aspects to the perception of light are brightness, color, and