What is the opponent process theory of color vision?
The opponent process theory suggests that the way humans perceive colors is controlled by three opposing systems. We need four unique colors to characterize perception of color: blue, yellow, red, and green. According to this theory, there are three opposing channels in our vision. They are:
- blue versus yellow
- red versus green
- black versus white
We perceive a hue based on up to two colors at a time, but we can only detect one of the opposing colors at a time. The opponent process theory proposes that one member of the color pair suppresses the other color. For example, we do see yellowish-greens and reddish-yellows, but we never see reddish-green or yellowish-blue color hues.
The theory was first proposed by German physiologist Ewald Hering in the late 1800s. Hering disagreed with the leading theory of his time, known as the trivariance of vision theory or trichromatic theory, put forth by Hermann von Helmholtz. This theory suggested that color vision is based on three primary colors: red, green, and blue. Instead, Hering believed that the way we view colors is based on a system of opposing colors.
As mentioned above, Hering’s opponent process theory clashed with the trichromatic theory that dominated his time. In fact, Hering was known to strongly oppose von Helmholtz’s theory. So which is correct?
It turns out that both of these theories are necessary to fully describe the intricacies of human color vision.
The trichromatic theory helps to explain how each type of cone receptor detects different wavelengths in light. On the other hand, the opponent process theory helps explain how these cones connect to the nerve cells that determine how we actually perceive a color in our brain.
In other words, the trichromatic theory explains how color vision happens at the receptors, while opponent process theory interprets how color vision occurs at a neural level.
In the 1970s, psychologist Richard Solomon used Hering’s theory to create a theory of emotion and motivational states.
Solomon’s theory views emotions as pairs of opposites. For example, some emotional opposing pairs include:
- fear and relief
- pleasure and pain
- sleepiness and arousal
- depression and contentment
According to Solomon’s opponent process theory, we trigger one emotion by suppressing the opposing emotion.
For example, let’s say you receive an award. The moment you’re handed the certificate, you may feel a lot of joy and pleasure. However, an hour after getting the award, you may feel a bit sad. This secondary reaction is often deeper and longer lasting than the initial reaction, but it gradually disappears.
Another example: small children becoming irritable or crying on Christmas a few hours after opening presents. Solomon thought of this as the nervous system trying to return to a normal equilibrium.
After repeated exposure to a stimulus, eventually the initial emotion wanes, and the secondary reaction intensifies. So over time, that “after-feeling” can become the dominant emotion associated with a particular stimulus or event.
You can test out the opponent process theory with an experiment that creates a negative afterimage illusion.
Stare at the image below for 20 seconds, and then look at the white space that follows the image and blink. Note the color of the afterimage you see.
If you prefer to do the experiment offline, you can do the following:
- one sheet of white paper
- one blue, green, yellow, or red square
- a square of white paper that is smaller than the colored square
- Place the small square of white paper at the center of the larger colored square.
- Look at the center of the white square for about 20 to 30 seconds.
- Immediately look at the plain sheet of white paper and blink.
- Note the color of the afterimage you see.
The afterimage should have the opposite color of what you just stared at because of a phenomenon known as cone fatigue. In the eye, we have cells called cones, which are receptors in the retina. These cells help us see color and detail. There are
- short wavelength
- middle wavelength
- long wavelength
When you stare at a specific color for too long, the cone receptors responsible for detecting that color become tired, or fatigued. The cone receptors that detect the opposing colors are still fresh, however. They aren’t being suppressed any longer by the opposing cone receptors and are able to send out strong signals. So when you then look at a white space, your brain interprets these signals, and you instead see the opposing colors.
The fatigued cones will recover in less than 30 seconds, and the afterimage will soon disappear.
The results of this experiment support the opponent process theory of color vision. Our perception of the image’s color is controlled by Hering’s opposing systems. We only see the opposing color when the receptors for the actual color become too fatigued to send out a signal.
Solomon’s opponent process theory may explain why unpleasant situations can still be rewarding. It could be why people can enjoy horror movies or thrill-seeking behaviors like skydiving. It may even explain phenomena such as the “runner’s high” and self-injurious behaviors, like cutting.
After developing his theory, Solomon applied it to motivation and addiction. He proposed that drug addiction is the result of an emotional pairing of pleasure and withdrawal symptoms.
Drug users feel intense levels of pleasure when they first start using a drug. But over time, the pleasure levels decrease, and withdrawal symptoms increase. They then need to use the drug more frequently and in larger quantities to feel pleasure and avoid the pain of withdrawal. This leads to addiction. The user is no longer taking the drug for its pleasurable effects, but instead to avoid withdrawal symptoms.
Some researchers don’t completely support Solomon’s opponent process theory. In one study, researchers didn’t observe an increase in withdrawal response after repeated exposure to a stimulus.
There are good examples that suggest the opponent process theory is valid, but other times it doesn’t hold true. It also doesn’t completely explain what would happen in situations involving several emotional stresses occurring at one time.
Like many theories in psychology, Solomon’s opponent process theory shouldn’t be considered the only process involved in motivation and addiction. There are several theories of emotion and motivation, and the opponent process theory is just one of them. Most likely, there’s a range of different processes at play.