Visual Perception

Perception is about taking the information that has already been received by the senses and making sense of it. The specific cells in the eye receiving the light signals work together with nerves traveling up to the brain to make sense of the visual data.

Fg. 1 An optical illusion, pixabay.com

Either way, the person's perception of which direction the shapes are moving in is completely different from their vision's clarity. Even if both people looking at the image have 20/20 visual acuity, their perception of the image can still be different.

The skills your eyes need to use depend on the conditions within your environment. Are you sitting in a dark room with no window? Are you outside at a carnival during the day? The visual skills you use will be different, and your perception of what you're seeing will also be different. There are three types of visual skills that you should know:

You need your photopic vision skill during the daytime or in an environment with adequate lighting. Outside during the day or inside with the lights on, your eyes and brain sense and interpret the colors around you through specific cells in your eyes called cone cells.

You use your scotopic vision skill in dark or low-light environments. In these conditions, rod cells in the eye are activated, allowing for better visual data interpretation even in low-light settings. Cone cells in your eye perceive light in well-lit settings. They are also responsible for perceiving color. The cones of our eyes are grouped around the retina's center. A depression in the retina's center called the fovea includes the highest concentration of cones.

Rod cells in your eye perceive light in low-lit settings, but they do not detect colors. These cells are distributed all over the retina and are solely responsible for detecting black and white. The light-sensitive molecule rhodopsin, found in rods, is crucial for allowing vision in low-light conditions.

Mesopic vision, or twilight visual perception, is the skill to detect and interpret data in semi-dark settings. Street lighting at night, outdoor night settings, and other environments with lower-light lamps will activate this visual skill. Experts believe that mesopic vision combines the use of rod cells and cone cells, or scotopic vision and color perception.

Depending on your setting, your eyes use different skills to receive information from your environment. How well these skills work varies from one person to another. One person may have an excellent photopic vision but struggle with color perception. Those who are color blind have a specific type of visual perception disorder involving the eye's cone cells.

Vision first happens through the cornea, lens, and retina: the eye's sensory faculties. The cornea is the protective outer layer that focuses light on our eyes. The lens directs the light rays to the retina as light enters the cornea. The retina is the eye's inner layer responsible for sensing images and sending signals to the brain through the optic nerve.

The retina turns light into electric signals by the rod and cone cells in the eye. Rods and cones convert light into neural impulses received by the optic nerves. The optic nerves are connected to the brain and are responsible for transmitting neural impulses to the brain.

Once the optic nerves receive the signals, they go through the central ganglia in the brain. The signals go through the visual cortex, the brain's primary area of processing and interpreting visual information.

One of our cerebral cortex's four lobes, the occipital lobe, is devoted to visual processing. This area contains a significant portion of the visual cortex, where interpretation of visual information happens. The whole visual perception process also uses two other lobes of the cerebral cortex: the parietal and temporal lobes. While most raw visual data processing occurs in the occipital lobe, the parietal lobe helps with recognition and the temporal lobe with memory and association.

Richard Gregory is a psychologist who theorized that perception is a constant process of hypothesis testing. According to the theorist, the ability to interpret vision relies on previous "schemas" or former experiences.

Gregory explains that most of the visual components our body's sensory faculties can gather are lost 90 percent of the time. Only a fraction reaches the brain for processing. Practical evidence supporting the top-down processing theory includes optical illusions, where people have different perceptions even with relatively similar visual skills.

Bottom-Up Processing Theory by James Gibson (1972)

Neither theory can explain the full extent of visual perception, leading some experts to believe that the process involves the perceptual cycle where top-down and bottom-up processing interact, as presented by Neisser (1976).

Fg. 3 Optical illusion in a desert, pexels.com