About inclusivity in interfaces and how designers can take color vision characteristics into account. In this article, I share basic information about color vision characteristics, as well as useful tools and resources that I use myself. I would be happy if you could continue the discussion in the comments with your knowledge and case studies!
Color, the eye, the brain: a little theory
How a person sees and perceives color can influence many things: for example, their impression of a product and whether they feel comfortable interacting with it. This feature is not superficial: if the interface is well-designed, convenient, and pleasing to the eye, in most cases it will perform its tasks well. When comparing two websites with similar content, users will choose the one where they feel more comfortable, thanks to a well-designed UI.
But if you look a little deeper, you will find that there are cases when two people perceive the same interface in completely different ways. This can be influenced by the characteristics of color vision.
To understand the whole issue, you need to have an idea of what color is and how it is perceived by the human eye.
Color is not a property of an object, but rather a feature of its perception. For example, during the daytime or under artificial lighting, all objects have saturated colors. But when the level of illumination decreases, the contrast of colors also decreases—until all objects become gray (for example, in the middle of the night when there is no light at all).
We perceive color differently for a number of reasons. One of them is the structure and functioning of the human eye.
The retina of the eye has special receptors: cones and rods, of which there are an average of 7 and 130 million, respectively, in each person. The cones are responsible for color perception, and the rods are responsible for twilight and peripheral vision.
Rods are receptors for twilight vision. They always work, regardless of external conditions, and provide general visibility: thanks to them, we can see the outlines and sizes of objects. Cones, on the other hand, only work actively in bright conditions — as it gets darker, their intensity decreases, which is why objects appear gray.
In addition to the physical properties of the eye, color perception is influenced by a person’s psycho-emotional state and previous experience. That is, it is not only what a person feels here and now that is important, but also the emotions experienced in the past.
Reasons for different color perception
It turns out that differences in the perception of the same color can be caused by several reasons:
- Unequal number of cones in the retina. The more cones a person has, the more shades they can distinguish. There may also be disturbances in the functioning of the cones, which can lead to color vision disorders. Some of these are listed below.
- Differences in lighting levels. Visual interface elements are essentially pixels consisting of three primary colors: red, blue, and green. When these colors are combined or their intensity changes, they are also perceived differently. They only look the same under absolutely identical conditions — for example, in complete darkness. If light is added, it mixes with the light emitted by each element of the image, and perception changes.
- Psychological characteristics of a person. Much depends on the brain. For example, if we see a lemon at night, it will actually be gray. But the brain is likely to perceive it as yellow.
The context, experience, and personality traits of the user influence how they see the interface, but that is a separate and extensive topic.