What is opponent process theory.
The opponent color process works through a process of excitatory and inhibitory responses, with the two components of each mechanism opposing each other. For example, red creates a positive (or excitatory) response in a cell, while green creates a negative (or inhibitory) response. When this cell is activated, it tells the brain that you are seeing red. Meanwhile, there is an opponent cell that gets a positive response to green wavelengths of light and an inhibitory response to red.