Which theory suggests that color receptor cells are paired and work in opposition to each other?

The Opponent Process Theory is distinguished by its assertion that color vision is driven by opposing pairs of colors. According to this theory, certain color receptors are organized in pairs — specifically, red and green, blue and yellow, and black and white. When one color in a pair is stimulated, the other is inhibited. This mechanism explains various visual phenomena, such as afterimages, where staring at a color and then looking away reveals its opposite.

This theory complements the Young-Helmholtz Trichromatic Theory, which focuses on the existence of three types of color receptors (cones) that respond to different wavelengths of light (red, green, and blue). However, the Trichromatic Theory does not address the opposing nature of these color signals and how they interact in perception, which is where the Opponent Process Theory fills the gap.

Feature detector theory and place theory relate more to visual processing in terms of spatial frequency and specific feature recognition rather than the color perception mechanism directly. Thus, the Opponent Process Theory stands out due to its unique approach in explaining how color receptors operate in pairs and influence our overall experience of color vision.