Writer: Brain Guo

Human beings often assume that they all experience the world in approximately the same way. When individuals look at a sunset, or any other object of interest, the assumption is that everyone sees the same thing. However, the modern study of psychology, neuroscience, and evolution reveals a different truth about human perception. Each individual has a different visual experience from the rest of humanity. Due to differences in genetics, the structure of the eyes, the structure of the brain, and even evolutionary adaptation, no two individuals experience the world in exactly the same way. Each person’s sight is different from the other.

The differences in sight among humans are the result of evolution. Human vision has evolved over millions of years in response to the different environments in which our ancestors lived. Additionally, the differences among individuals are the result of natural selection choosing traits that provide advantages to those individuals. In the field of psychology, the understanding of these differences in vision among human beings allows for individuals to better understand the evolutionary background and consciousness of human beings.

The human eye is one of the most complex organs in the human body. Light enters the eye through the cornea and the pupil, and is focused onto the retina by the lens of the eye. The retina contains two types of photoreceptor cells that translate light into electric impulses that are transmitted to the brain: rods and cones. Rods allow individuals to see in the dark, while the cones are responsible for color vision (Purves et al. 241). However, the number of rods and cones that are present on the retina of each individual’s eye is different. Furthermore, research into the genetics of individuals has revealed that the structure of the retina differs from person to person (Wandell 52).

Individuals exhibit dramatic differences in their visual acuity. Some individuals have eyes that allow them to see at distances that are twenty feet away that individuals with average vision have to travel to ten feet to be able to view an object clearly. Others have myopia, hyperopia, or astigmatism. According to the World Health Organization, over two billion individuals in the world have some form of visual impairment (World Health Organization). These differences in visual acuity have both genetic and environmental origins. For instance, children who spend more time outdoors have lower incidences of developing myopia than those who spend much of their time focusing on nearby objects (Rose et al. 1275).

Some of these differences among human beings are the result of evolutionary adaptations. Human ancestors lived in a variety of environments across the planet. Some individuals may have had genetic adaptations that allowed them to see better in the dark, for instance, while others may have needed vision adaptations that allowed them to see better over long distances in open environments. Evolution is not a process of producing perfect adaptations for each environment; rather, it only requires adaptations that provide an advantage to those individuals with such traits compared to those without those traits. Thus, adaptations to vision exist in the current human population (Darwin 89).

Another example of differences among human beings is in their abilities to perceive colors. While the majority of humans have three types of cone cells in the retina that allow them to perceive colors in the visible spectrum, approximately eight of every hundred0 males and one of every hundred females of Northern European descent have a genetic condition that prevents them from correctly perceiving colors: color blindness (Birch 3). These individuals do not perceive fewer colors than other humans, but they experience colors in different ways. For instance, individuals with red-green color blindness find that red and green colors appear to be the same shade.

An individual’s ability to experience the world visually is even more complex than differences in visual acuity or color perception. In psychology, the idea of sensation and perception helps to explain the experience of vision among individuals. Sensation is the physical detection of external stimuli. Perception is the process that the brain performs in the recognition of those sensations. The visual cortex of the brain is continuously active and responsible for understanding visual experiences (Goldstein 97). Thus, in many cases, human beings do not see the world as it is; they experience the interpretation of the visual world created by their brains.

One way to investigate the differences in vision among individuals is to study optical illusions. For instance, the Müller-Lyer illusion depicts two lines of the same length, yet one line appears longer than the other due to the visual orientation of the arrows along the lines. Additionally, a visual phenomenon that became popular on social media involved images of a dress that some individuals said was blue and black, while others stated that it was white and gold. Scientists have found that the differences in perception of the dress were due to the individual differences in each person’s visual cortex (Lafer-Sousa, Hermann, and Conway 796).

Beyond vision alone, human cognition introduces more fascinating differences in perception among individuals. Experts in specific fields notice visual details that individuals without that area of expertise are unaware of. For instance, radiologists are able to identify abnormal conditions in medical images at rates of fractions of a second, while individuals who are experienced artists are able to notice visual differences in colors or images that individuals who are not artists cannot notice (Goldstein 102).

Age is another factor that contributes to the differences in vision among individuals. Vision changes with the age of individuals. For instance, young infants are born with relatively poor vision and depth perception. However, their vision and depth perception develop over several months after birth. Additionally, individuals typically experience changes to the shape of their eyes during adolescence that result in nearsightedness. As individuals reach the age of fifty, conditions such as cataracts, difficulty in seeing high-contrast objects, and decreased peripheral vision become more common (Santrock 145).

These changes to vision as a result of the age of individuals indicates that each individual has experienced a variety of visual perceptions throughout their lives. For example, young adults tend to have better motion detection abilities than elderly individuals, which may be an evolutionary adaptation to improve the survival of those individuals (Buss 61).

In addition to each individual’s genetics and biology, modern technology has also begun to influence the sight of human beings. The increased exposure of individuals to screens has contributed to myopia and visual strain. Some researchers have even labeled myopia as an epidemic among the younger generations of human beings (Holden et al. 1036). While the genetics of each individual has played a crucial role in the development of myopia, the environmental differences among individuals has contributed to their visual experiences.

In addition to the visual differences introduced by biology and genetics, each human being also experiences the world differently due to their unique memories, experiences, and psychology. For instance, individuals with a background and experiences with birds can recognize bird species much more quickly than individuals who have little experience with birds. Additionally, individuals with psychological and mental illnesses can experience visual phenomena that differ from those without such conditions. Individuals with schizophrenia experience visual illusions more often than other individuals with mental illnesses, while individuals with prosopagnosia are unable to recognize the faces of individuals with whom they are familiar (Gazzaniga, Ivry, and Mangun 381).

These differences among human beings raise important questions within the field of philosophy. For instance, can another human being truly understand the experiences of another? These types of questions are related to the concept of consciousness and the nature of objective experiences of the world. Thus, the different ways that human beings experience the world visually raises these philosophical concerns.

Another factor related to the differences in vision among humans is the concept of evolution. As stated above, human vision evolved over millions of years to adapt to the environments in which human beings lived. Each of these evolutionary adaptations have allowed humans to better survive and reproduce. Furthermore, some of these traits are present in human populations as a result of the survival of individuals who had those traits. Thus, as a result of the different factors related to human biology, psychology, and evolution, human vision is different from individual to individual.

Human beings have different sight from each other due to the combination of factors that influence vision: genetics, anatomy, environment, age, psychology, and evolution. Humans do not simply see the world around them with their eyes. Rather, they experience the world as it is interpreted by their brains. These adaptations and features of the human visual system have evolved over hundreds of thousands of years as a means of enabling human survival. Thus, every individual sees the world in a version of reality that is uniquely their own.

While it may seem like individuals who are engaged in the same activity experience the world in the same way, each individual perceives the world differently from others. This ability of the human eye and brain to experience the world as an individual is one of the greatest achievements of nature. Thus, no two individuals in the world experience the world in the same way.

Works Cited

Birch, Jennifer. Worldwide Prevalence of Red-Green Color Deficiency. Journal of the Optical Society of America A, vol. 29, no. 3, 2012, pp. 313–320.

Buss, David M. Evolutionary Psychology: The New Science of the Mind. 7th ed., Routledge, 2024.

Darwin, Charles. On the Origin of Species. Oxford University Press, 2008.

Gazzaniga, Michael S., Richard B. Ivry, and George R. Mangun. Cognitive Neuroscience: The Biology of the Mind. 6th ed., W. W. Norton, 2024.

Goldstein, E. Bruce. Sensation and Perception. 11th ed., Cengage Learning, 2022.

Holden, Brien A., et al. “Global Prevalence of Myopia and High Myopia.” Ophthalmology, vol. 123, no. 5, 2016, pp. 1036–1042.

Jordan, G., and J. D. Mollon. “A Study of Women Heterozygous for Colour Deficiencies.” Vision Research, vol. 33, no. 11, 1993, pp. 1495–1508.

Lafer-Sousa, Rosa, Katherine L. Hermann, and Bevil R. Conway. “Striking Individual Differences in Color Perception.” Current Biology, vol. 25, no. 13, 2015, pp. R545–R546.

Purves, Dale, et al. Neuroscience. 7th ed., Oxford University Press, 2024.

Rose, Kathryn A., et al. “Outdoor Activity Reduces the Prevalence of Myopia in Children.” Ophthalmology, vol. 115, no. 8, 2008, pp. 1279–1285.

Santrock, John W. Life-Span Development. 19th ed., McGraw-Hill, 2023.

Wandell, Brian A. Foundations of Vision. Sinauer Associates, 1995.

World Health Organization. World Report on Vision. WHO, 2019.