Color Perception: Characteristics, Functioning And Alterations

Color perception

Although it may seem objective, color is a private and therefore subjective perceptual experience (just like the perception of pain). But… What does color perception entail? What depends on whether we perceive some colors or others? What makes us perceive red, blue or yellow?

In this article we will talk about how colors are perceived, the different colors and the pathologies associated with color perception, among other topics.

What is the color?

There are different definitions for color. Color can be understood as a perceptual response to objects and lights that gives them certain qualities (such as green). It can also be considered a characteristic of the perceptual response.

To define colors, in our daily lives we usually use examples (such as “blue is like the sea”, “green is like trees” or “black is like darkness”).

Factors that determine color perception

There are four important factors when it comes to perceiving colors. These are:

Color constancy

On the other hand, color constancy also plays a key role in color perception; This implies that we perceive colors “always” the same (in natural conditions), that is, red for us will always be red, for example.

In any case, this record is partial, since color perception changes a little when lighting changes.

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How do we perceive colors?

The colors we perceive are the result of the mixture of wavelengths reflected by objects; we can say that light is filtered by the surface on which it falls. There are three types of wavelengths:

The remaining colors (different from these three) result from the mixture of these three wavelengths.

The perceptual process

Visual perception is determined by neural processing at all stages of the visual system. This depends on the cones, among other variables.

At a physiological level, a selective discoloration of visual pigments occurs in chromatic adaptation. This involves specific neurons in a specific area of ​​the brain, area V4, located in the extrastriate cortex (secondary visual cortex).

Striatal neurons respond to visual stimulation; This answer is related to the wavelength (which determines the type of color we see), and the response of V4 neurons is related to perception.

Types of colors

There are two types of colors:

1. Achromatics

These colors have no hue; It’s about black, white and grey. At the brain level and from sight, we perceive achromatic colors with rods (receptors), which are photoreceptor cells in the retina responsible for vision in low light conditions.

2. Chromatics

Chromatic colors have a nuance: they are all “the other colors”, such as blue, red, green… Unlike the previous ones, the receptors for these colors are the cones (photosensitive cells located in the retina, responsible for us perceiving colors in one way or another).

Functions of color perception

Color perception has a series of functions for humans, but also for some animals (since not all see in color). Let’s get to know them:

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1. Adaptive

Perceiving colors implies a value for survival and therefore an adaptive value, since it allows: searching for food, detecting dangers and interpreting emotions.

Color perception results from an evolutionary development (for example, the fact of detecting fruit among the foliage increases the probability that that animal will have food, eat, and therefore survive).

2. Aesthetics

The fact of perceiving colors involves being able to appreciate beauty and aesthetics, as well as appreciate the nuances of objects, landscapes, art (for example in paintings), of people, etc.

3. Perceptual organization

Perceiving different colors allows us to organize the world into separate areas or segments.

Associated vision pathologies

The basic alteration of color perception is color blindness. This alteration implies that the person sees some colors different from the rest of the people, and “confuses” or exchanges some of them, or that he or she sees directly in black and white.

It is a genetic alteration in the ability to distinguish colors, which affects 8% of men and 1% of women (because it is recessive linked to sex). Two types are known:

1. Monochromatism

The first type of color blindness is a rare form of color blindness (complete color blindness), which occurs in 10 people out of every million. Affected people do not have functional cones, that is, they show vision only with rods; They come in white, black and grey. On the other hand, they need protection from sunlight.

2. Dichromatism

The other type of color blindness involves blindness to some colors. It is linked to sex, and There are three known subtypes: protanopia, deuteranopia and tritanopia.

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Deuteranopia

It is the absence of green retinal photoreceptors (medium waves). They see the same colors but with a different neutral point.

Protanopia

It is the total absence of retinal red color photoreceptors (long waves).

Tritanopia

It is a very rare condition in which blue retinal photoreceptors (short waves) are absent. This is very rare.

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