Color perception: characteristics, functioning and alterations

Although it may appear objective, color is a private perceptual experience and therefore subjective (as is the perception of pain). But … What does color perception involve? What does the fact that we perceive certain colors and others depend on? What makes us perceive a red, a blue or a yellow?

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

    What is color?

    There are different definitions of color. The color can be understood as a perceptual response to objects and lights which gives them certain qualities (such as green). It can also be seen as a characteristic of perceptual response.

    To define colors, in our daily life, we often 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 in perceiving colors. These are:

    • Wavelength and illumination: In other words, how objects reflect light.
    • The effect of the surrounding area: Also called simultaneous contrast.
    • The observer’s level of adaptation: Presence of light or darkness (the darker it is, the more blue we perceive [longitud de onda corta]).
    • The memory of color: Knowing the characteristic color of certain objects influences our perception.

    Color consistency

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

    However, this constancy is partial, because color perception changes a bit when lighting changes.

    How do we perceive the colors?

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

    • Short wave: blue color.
    • Medium wave: green color.
    • Long wave: red.

    The remaining colors (other than these three) are the result of mixing these three wavelengths.

    The perceptual process

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

    At the physiological level, there is a selective discoloration of visual pigments in chromatic adaptation. These are neurons specific to a specific area of ​​the brain, the “V4 area”, located in the extraterrestrial cortex (secondary visual cortex).

    Striated neurons respond to visual stimulus; this response is related to the wavelength (This 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.achromatic

    These colors have no shades; these are black, white and gray. At the level of the brain and the sight, one perceives achromatic colors with rods (receptors), which are photoreceptor cells in the retina responsible for vision in low light conditions.

    2. Chromatic

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

    Color perception functions

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

    1. Adaptive

    Perceiving colors implies a value for survival, And therefore an adaptive value, because it allows it: to search for food, to detect dangers and to interpret emotions.

    Color perception results from evolutionary development (for example, the detection of fruit among the foliage increases the probability that this animal will have food, coma and therefore survive).

    2. Aesthetics

    Perceiving colors is also being able to appreciate beauty and aesthetics appreciate the nuances of objects, landscapes, art (For example in pictures), people, etc.

    3. Perceptual organization

    The perception of different colors allows you to organize the world into separate areas or segments.

    Associated vision pathologies

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

    It is a genetic disorder in the ability to distinguish colors, affecting 8% of males and 1% of females (to be gender-related recessive). Two types are known:

    1. Monochromatism

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

    2. Dichromatism

    The other type of color blindness involves blindness to certain colors. It’s related to sex, and three subtypes are known: protanopia, deuteranopia and tritanopia.

    Deuteranopia

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

    Protanopia

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

    tritanopsia

    This is a very rare condition in which blue retinal photoreceptors (shortwave) are absent. It’s very rare.

    Bibliographical references:

    • Monserrat, J. (1998). Visual perception. New university library of psychology. Madrid
    • Goldstein, EB (2006). Sensation and perception. 6th edition. Debate. Madrid
    • Manzanero, A. Psychology of perception. Complutense University of Madrid (UCM)

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