Back in college, I suffered a psychotic break that made me question the nature of reality. In an attempt to understand what was happening to me, I jumped down the metaphysical rabbit hole, studying heaps of philosophy and getting wrapped up in the nuances of the cognitive sciences.

A lot of this made me question whether my subjective reality is the same as the subjective reality of everyone else. Given that I was experiencing hallucinations and living in delusional fantasies that no one else seemed to have, I came to realize that every person’s inner world looks different — our respective inner worlds do not have to align at all.

This is particularly interesting because around the time I was coming to these conclusions, I also stumbled across color theory. Most of us have had moments in which we’ve wondered whether the blue we see really is the same as the blue that another person sees. What, after all, is the real truth behind our eyes? Do our perceptions indicate that we each live in a completely different reality from the person next to us? What if we switched bodies, would each of us find ourselves in a bizarre and unrecognizable world?

How Experience Is Formed

Let’s begin our exploration of the subjective by revisiting a well-known thought experiment:

If a tree falls in a forest, and no one’s around to hear it, does it make a sound?

If you’re like I was when I first started delving into philosophy, you’ll answer this question with a resounding “yes.” However, if we really deconstruct what is happening in this scenario, we’ll find that the answer is actually a less obvious “no.”

In essence, this question demonstrates a problem with language. The way I personally first interpreted the question reflected the thought that sound does not need a witness to exist. However, as it usually does, the reality of things gets more complicated when we begin to acknowledge the complexity of language and its role in this situation.

To illustrate what I mean, we should first distinguish between “sound” and “sound waves.” These are the labels we use to distinguish between a subjective qualia, and an objective phenomena, respectively. When a tree falls, it perturbs a lot of air, causing a rippling percussion of energy to radiate out amongst the surrounding molecules of air. Without an observer, this process is merely just mechanical pieces of the universe playing out an effect after a cause.

What is the sound of one hand clapping? If you wave your hand through the air, do you hear anything? Not usually — under normal circumstances, simply perturbing air lightly does not generate sound, despite the perturbed air radiating out in a similar fashion as it does when the tree falls.

Credit: Chittka L, Brockmann/Wikimedia Commons/CC BY 2.5

From this, we can confidently say that sound exists as a result of translating a phenomena in the outside world into an experience in our inner worlds. In the case of a tree falling, that air would go through a process that renders it as sound: the air would first enter the ears of an observer and reverberate off the eardrum. This causes two small bones, the hammer (malleus) and the anvil (incus), to knock into one another before they translate against a third bone, the stirrup (stapes). The stirrup then creates waves within the cochlea, a spiral-shaped structure of the inner ear.

Within the cochlea are small hairs called stereocilia, which act like transistors. When the stereocilia are pushed around by the moving fluid of the cochlea, they translate the stimulus into an electrochemical signal which travels across the auditory nerve into the brain. From there, the brain takes that information and uses it to construct an experience, in a process called the Cartesian Theater.

How Color Is Formed

In a similar manner, color is formed when our eyes translate light phenomena into a dazzling display of colors. The color we “see” is actually what happens when the light that bounces about the world without being fully absorbed by any particular object is refracted through the lenses of our eyes, where it is directed towards a specialized group of cells, called the “cones” and “rods.”

Cones are activated by high levels of light and are what allow us to see color. Rods are activated by low levels of light and are what allow us to see in low-light levels.

L: Schematic diagram of the human eye. Credit: Holly Fischer/Wikimedia Commons/CC BY 3.0 R: Cross section of the retina. Rods are visible at far right. Credit: Cajal/Wikimedia Commons/CC BY-SA 3.0

Both cones and rods exist in the back of the eye, the retina. Similar to the way in which the stereocilia in the ear translate information into a pattern the brain can use, these receptor cells translate the information contained in light waves into a signal that the brain uses to construct an image of the external world.

The average person has three types of cone cells, which detect ranges of light in the blue, green, and red wavelengths. It is through the combinations of inputs from these cells that our brains can piece together the full spectrum of the rainbow, an ability which every single person does not have. This is when we remember that the experience of interpreting light is not the same for everyone.

Colorblind people often only have two types of cones, which give many colors a “dull” appearance. The genetic mutation called tetrachromacy enables those who have it, about 12 percent of all women, to have four types of cones, and thus experience a much wider range of colors than the average person. Because the tetrachromacy gene is only expressed when present on the pair of X-chromosomes, men cannot have the mutation.

These variances in light and color perception are indicators that there does exist a wide variety of people who inherently see the world differently from the “average person.” It still, however, does not answer the question: do two people with the same vision see the exact same colors?

An Experiment With Experience

In 2009, a study done at the University of Washington tested the color perception of squirrel monkeys. Like colorblind humans and most other mammals, these monkeys only have two types of cone cells. The experiment first tested how the monkeys reacted to colorful dots on a screen when paired with the reward of a sip of juice. Researchers found that the monkeys could pick out blue and yellow dots from a field of gray ones, but could not distinguish between the red and green dots.

Perhaps your blue is my red. Each of us comes to the world with an individual perspective and experiences life in a unique way.

The monkeys were then injected with an engineered virus which worked to mutate specific genes in the monkey’s eyes, changing their green-receptive cells into red-receptive cells. Monkeys are not neurologically wired to process the color red, but researchers found that after this gene therapy, the monkeys had no problem picking out the red dots.

This raises the question: What exactly happened that enabled the monkeys to perceive the new color? Was the color the same red that we perceive, or is the experience of perceiving the red color fundamentally different for the injected squirrel monkeys than it is for most humans?

The questions we ask in regards to the squirrel monkey experiment are similar to the ones we ask about our brains and what they do when we experience color for the first time. We can conclude that none of us were born inherently knowing color — we have each had to go through the process of experiencing every single color for the first time as we have encountered them after leaving the womb.

And though we still cannot say for certain that most people experience color the same way, we may assume that each person’s interpretation of color may not be as innate or biological a process as we tend to believe. It is entirely possible that our brains have learned how to express different wavelengths of light according to our differing subjective realities.

Perhaps your blue is my red. Each of us comes to the world with an individual perspective and experiences life in a unique way. If we ruminate on the differences these factors create in our perspectives of the world, we may bring ourselves to better empathize with each other as we go through our lives.

My experiences and research have taught me that whatever I thought I knew can be questioned. If more people understand that their internal worlds are not absolute, then our collective experience as human beings may have room to embrace more understanding, since we will base our interactions in the fact that we are all unique and come with novel perspectives that should be cherished and nurtured. Only then will we be able to manifest a collective paradise here on Earth.