No One Can Truly Know What It Feels Like to Be You

How socioeconomic and biological factors shape the self, beyond the brain.

Posted June 2, 2026 | Reviewed by Lybi Ma

With every moment, the world is made new, while we remain unaware of renewal in our existence. Life comes like a stream, ever fresh and fresh again, continuously revealing itself within the body. Rumi

We have all heard the advice: To understand another person, you should put yourself in their shoes and see the world through their eyes. But is that even possible? It appears not. Maybe this is exactly why we can never fully understand each other. How often have we been surprised by the actions of someone we believed we understood well, when they acted in a way that is totally unlike their usual behavior?

In his famous book— What Is It Like to Be a Bat? —Thomas Nagel puts it this way: An organism has conscious mental states if and only if there is something that it is like to be that organism, something that exists for that organism. To be a "self" means to have an inner world that can only be touched from the inside. This inner quality is deeply personal and private. From this view, being me is no different from any other inner experiences. It is made of the same stuff as consciousness itself: the taste of that first cup of coffee in the morning, the orange glow of a sunset by the sea, or the sense of relief after a difficult exam.

Nagel, like other philosophers such as David Chalmers, argues that science alone is not enough to account for these inner qualities. Physical explanations cannot claim to have uncovered the whole truth of what it means to be us. His famous metaphor: We will never truly know what it is like to be a bat, just as I will never know what it is like to be you, even if I knew every last detail of your brain activity [1].

But here is something Nagel and others have not considered: Sometimes we do not even have an accurate understanding of ourselves. We tend to think of our inner experience of "being me" as a continuous, stable feeling that lasts our whole lives. But studies from sociology, psychology, neuroscience , and biology now show that the people we live with, our physiological and pathological conditions, and even the tiny organisms living inside our bodies all play a role unconsciously in shaping these inner experiences.

In what follows, I will focus on just one piece of these findings to show something important: Not only do we lack a complete picture of what it is like to be someone else, but we also do not even have a fully accurate picture of what it is like to be ourselves. It is revealed that this understanding shifts throughout our lives, shaped by many different forces.

It has been shown that certain parasites appear capable of altering their hosts' behavior in ways that increase the parasites' chances of survival and reproduction. The lancet liver fluke, for example, can influence infected ants to climb vegetation and clamp onto grass tips, increasing the likelihood that grazing animals will consume them and complete the parasite's life cycle. Some other parasites manipulate the brains of insects, crustaceans, and fish, transforming ordinary living beings into vehicles for their own transmission.

Influencing the Systems That Shape Minds

One of the most intriguing examples is Toxoplasma gondii, a protozoan parasite whose life cycle ultimately depends on cats. Toxoplasma gondii appears to subtly reshape the behavior of infected rodents, reducing their natural fear of cats and making them more likely to take risks. In a remarkable twist of biology, a microscopic parasite may influence decisions that ultimately increase its own chances of completing its life cycle. The situation in humans is far less clear. Some studies have reported associations between latent Toxoplasma infection and differences in personality traits, risk-taking , reaction times, or certain psychiatric conditions. At the same time, other findings remain controversial or difficult to interpret. Correlation does not establish causation, and the evidence is far from definitive [2].

Parasites are not the only organisms capable of influencing the systems that shape minds. Each of us carries a vast community of microorganisms, trillions of bacteria, fungi, and viruses that inhabit our skin, airways, and especially our gastrointestinal tract. Collectively known as the microbiome , these organisms are increasingly recognized as active participants in a complex dialogue between the gut and the brain. They communicate through multiple pathways, including the vagus nerve , the immune system, and a wide range of biologically active molecules, some of which can affect neurotransmitter signaling and brain function. Most of the time, this relationship is mutually beneficial: We provide a habitat and nutrients, while our microbial partners help digest food, train the immune system, and contribute to overall health [3]. Yet when this ecosystem becomes imbalanced, a condition known as dysbiosis, the consequences may extend beyond the gut. Growing evidence suggests that disruptions in the microbiome can influence mood, stress responses, cognition , and vulnerability to certain mental health disorders. The idea that microscopic organisms within us can shape aspects of our mental life may seem surprising. Still, it further blurs the boundary between where "we" end and our biological partners begin [4]. Yet even the possibility raises a fascinating question: If a biological influence silently affects our motivations and judgments, would we realize that we are under the command of another being, or would we experience those altered thoughts as our own?

These examples, from the inner world of our bodies, along with other factors such as genes , nutrition , the immune system, hormones , and social and economic conditions, shape our inner, subjective experiences. (I've tried to explore these in my other writings for Psychology Today , as best as I can.)

This feeling of self is constantly being renewed. And as it changes, so does our inner experience of ourselves and the world around us. And that, in turn, affects our thoughts, our decisions, and the choices we make.

We usually assume that people are responsible for their actions. We judge others. But the sheer complexity of each person's individuality – and all the forces that shape it – should make us more cautious in those judgments. Just as we ourselves are constantly changing, we need to stay aware that others are too.

Nagel, T. (1979). What is it like to be a Bat? Cambridge University Press.
Castaño Barrios, L., et al. (2021). Behavioral alterations in long-term Toxoplasma gondii infection of C57BL/6 mice are associated with neuroinflammation and disruption of the blood-brain barrier . PLoS One, 16(10), e0258199.
Martin, C. R., Osadchiy, V., Kalani, A., & Mayer, E. A. (2018). The Brain-Gut-Microbiome Axis . Cell Mol Gastroenterol Hepatol, 6(2), 133-148.
Rees, T., Bosch, T., & Douglas, A. E. (2018). How the microbiome challenges our concept of self . PLoS Biol, 16(2), e2005358.

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Hamid Zand, Ph.D., is a professor of Biochemistry at the Department of Cellular and Molecular Nutrition at Shahid Beheshti University of Medical Sciences in Tehran, Iran.

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This article is part of the Bringwise Psychology Journal — daily insights on human behavior, mental health, and personal growth.