An Introduction To The Neuroscience of Consciousness (Part I)

Consciousness is arguably the biggest mystery of the universe. It is about what it is like to be me, you, or another species. For some, it is about how matter becomes imagination (Tononi & Edelman, 1998). At its core, it is about subjective experiences. This post serves as a friendly introduction to the topic.

I will focus on the neuroscience of consciousness, its philosophical background, how we study consciousness, and the most prominent theories.

Enjoy.

Before You Read

I’m not an expert on the topic. I have just read some papers about it and started to (indirectly) research it in birds.

Plus, consciousness is a huge topic that cannot be summarized in a single article. This is just a general overview. If you want to read more about the topic, I recommend checking the 30 references I used at the bottom and throughout this article.

Table of Contents

1. The Philosophical Problem
2. How Neuroscientists Do Research On Consciousness?
3. Book Recommendations

1. The Philosophical Problem

For a long time, consciousness was only a topic for philosophers.

They wrestled with questions about the nature of the mind and the subjective experience, the “what it is like,” that we call consciousness. This was considered something abstract and metaphysical, far from the practical and empirical methods of scientific inquiry. Luckily, this all changed with the pioneering work by Crick & Koch (1990), who suggested that consciousness could be studied scientifically through the identification of the “neural correlates of consciousness” (NCC). This refers to the specific brain activity that corresponds to conscious experience. For example, what is the specific brain activity when you see red and not blue? Or, even more generally: what is the specific brain activity when you report seeing something when you don’t?

Since then, neuroscience has increasingly become the field where many of the questions about consciousness are being addressed. However, philosophy continues to play a central role in shaping how we approach these questions. Why? Well, because definitions, categories, and frameworks provide the “semantics” on which modern science builds. For instance, theories about consciousness, its origins, and its mechanisms often arise from these philosophical considerations about what it means to “be” conscious and the nature of the experience.

Below are some key philosophical ideas that shape consciousness research:

A. -isms

Anil Seth (2021) in Being You: A New Science of Consciousness summarizes the ongoing philosophical influence by highlighting the “-isms”—different philosophical perspectives on consciousness:

• Functionalism: Consciousness depends on the functions performed by the brain, not on its physical structure.
• Materialism: Consciousness arises from physical processes in the brain.
• Dualism: Consciousness and physical reality are separate things.
• Panpsychism: Consciousness is a fundamental property of all matter.
• Idealism: Consciousness is the primary reality, and the physical world emerges from it.
• Illusionism: Consciousness is an illusion; it doesn’t exist as we experience it.

So, if consciousness is seen as the result of brain function (materialism), researchers will focus heavily on neural activity as the primary explanatory factor. If consciousness is considered a fundamental property of the universe (panpsychism), researchers might look for consciousness-related phenomena even in simpler organisms or non-living matter.

B. The Hard and Easy Problem(s)

David Chalmers (1995) introduced one of the most famous philosophical problems in the study of the brain. He distinguished between two types of problems related to consciousness: the easy problems and the hard problem.

• Easy problems: identifying the neural substrates of conscious perception, memory, and other cognitive functions.
• Hard problem: explaining how the brain, a physical entity, generates subjective experience.

The hard problem is about understanding why that activity feels like something—that is, why it gives rise to personal experiences, or qualia. In contrast, the easy problems focus on observable processes, like how the brain processes sensory input or stores information. However, the hard problem delves into why those processes are accompanied by conscious awareness.

To visualize this issue, let’s focus on another popular thought experiment proposed by Thomas Nagel (1980): What is it like to be a bat?

Bats are fascinating animals. Despite being mammals, they fly and echolocate. This perception allows them to emit ultrasonic sounds that bounce through objects or things that are surrounded by the animal. The bats listen to the echoes of these bounces and behave based on that. Try to do this by yourself. Close your eyes and try to make a “click” sound with your tongue. Now, imagine the sound waves reaching your coffee mug. Then, imagine those waves bouncing back to you, creating a mental picture of the size, texture, and more details about the mug.

So that’s what it’s like to be a bat, right? Well… not for Nagel. According to him, although we can study a bat’s behavior and biology, we can never truly understand what it feels like to be a bat. The correct answer to this question isn’t imagining what we would feel as a bat, but rather recognizing that only a bat can know what it feels like to be a bat. This is the hard problem: understanding subjective experience is different from studying objective processes. So, while we may one day solve the easy problems, the hard problem of consciousness is beyond the limits of the scientific method. That’s why, for many, the hard problem is impossible to resolve.

But this is not the only philosophical approach.

Phenomenological vs. Access Consciousness

Block (1995) suggested distinguishing between different types of consciousness.

He argued that having a pure subjective experience—like the redness of red—is different from consciously perceiving that red. For example, if I show you an image briefly, you may be able to consciously perceive it and report, “Yes, I’ve seen that.” However, this conscious recognition is different from the actual feeling of seeing that image—the “what it’s like” to see it. In this distinction, the first type of consciousness is access consciousness (i.e., the ability to report whether you’ve seen the image), while the second type is phenomenal consciousness (i.e., the subjective experience of seeing the image).

This distinction became a crucial development in the science of consciousness. It allowed neuroscientists to focus on studying access consciousness—the processes involved in conscious perception—and to explore the boundaries of conscious experiences.

D. Illusionism

This is when things get spicy.

Illusionists deny the hard problem entirely. Why? Well, because they challenge the very existence of subjective experience as we understand it. For illusionists, the problem of consciousness is not one of trying to explain how the brain generates subjective experience, but rather understanding why we are so convinced that such an experience exists at all. In short, they argue that consciousness, particularly phenomenal consciousness as we perceive it, is an illusion. One created by the brain. In short, they suggest that the hard problem is misguided because consciousness, in the way we experience it, does not exist as we typically understand it. In this view, once you accept that consciousness is an illusion, the need for an explanation vanishes.

Yeah, they just erase the problem entirely.

One of the leading proponents of illusionism is Keith Frankish (2016), who argues that consciousness should be understood as an evolutionary adaptation that provides a useful fiction—an illusion of subjective experience that helps the brain interpret and interact with the world more effectively. Similarly, Daniel Dennett argued that what we call consciousness is simply a narrative that the brain constructs to make sense of its processes.

2. How Neuroscientists Do Research On Consciousness?

Research on consciousness is complex, and how scientists approach it often depends on how they define consciousness itself. But despite this challenge, there are several classic experimental methods that have proven valuable in uncovering the mysteries of subjective experiences. Here are some of the key methods:

1. Binocular Rivalry

Binocular rivalry occurs when each eye is presented with a different image at the same time. In this situation, the brain doesn’t merge the two images; instead, it alternates between them, creating a shifting perception. This phenomenon is useful for studying the neural correlates of conscious perception—the specific brain regions involved in the experience of being consciously aware of something.

• Why it matters: By observing how the brain responds to this alternating perception, scientists can identify neural mechanisms that contribute to the conscious experience of seeing one image at a time.

2. Priming

Priming is a psychological phenomenon where exposure to one stimulus affects how we respond to a subsequent stimulus, often without conscious awareness. For example, if you see a picture of a dog, you might be faster to recognize the word “bone” afterward.

• Why it matters: Neuroscientists use priming to explore unconscious vs. conscious perception, shedding light on the differences between automatic processes and those we are consciously aware of. This helps researchers understand how much of our behavior is influenced by unconscious inputs.

3. Dreams

Dreams provide an intriguing and natural state of altered consciousness. Since dreams occur when we’re asleep, they offer a unique glimpse into what happens when consciousness is “switched off” to some extent but still active.

• Why it matters: Researchers like Siclari et al. (2017) have used high-definition EEG to predict and map dream content, identifying a posterior cortical hot zone that is activated during dreaming. By studying dreams, neuroscientists gain insights into the neural mechanisms underlying altered states of consciousness.

4. Other Methods

• The Mirror Test (Boyle, 2017): This test is used to assess self-awareness by determining if an animal recognizes itself in a mirror, a sign of higher-order consciousness.
• Psychedelics & Altered States (Yaden et al., 2021): By studying the effects of psychedelics, scientists investigate how substances can alter conscious experiences, providing clues about the brain’s role in perception and awareness.
• Metacognition Experiments (Fleming, 2023): These experiments study how individuals assess their own mental states, offering insights into how we become aware of our thoughts and how we know what we know.
• Illusions, such as the Rubber Hand Illusion (Constantini & Haggard, 2007): In this illusion, participants experience a fake hand as their own, revealing how the brain constructs the sense of body ownership and how conscious experience can be manipulated.

3. Book Recommendations

If you’re interested in learning more, here are some books worth reading:

• Being You: A New Science of Consciousness – Anil Seth
• Consciousness Explained – Daniel Dennett
• The Ego Tunnel: The Science of the Mind and the Myth of the Self – Thomas Metzinger
• Consciousness and the Brain: Deciphering How the Brain Codes Our Thoughts – Stanislas Dehaene
• A Universe of Consciousness: How Matter Becomes Imagination – Giulio Tononi & Gerald Edelman
• In Consciousness We Trust: The Cognitive Neuroscience of Subjective Experience – Hakwan Lau

Final Thoughts

Summarizing consciousness in one article is not fair.

My goal was to provide a friendly introduction to the topic. Philosophical ideas were violently summarized here. If you are interested, I highly encourage you to read the references.

That was enough philosophy for this post. In part II, I will try my best to summarize some theories of consciousness. Spoiler alert: Whether something does or does not have consciousness depends on how you define it. From here, things get spicy, and drama shows up.

I hope you enjoyed reading this.

References

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Baars, B. J. (1997). In the theatre of consciousness. Global workspace theory, a rigorous scientific theory of consciousness. Journal of consciousness Studies, 4(4), 292–309.

Baars, B. J. (2004). Global workspace theory of consciousness: Toward a cognitive neuroscience of human experience. Progress in Brain Research, 150, 45–53. https://doi.org/10.1016/S0079-6123(05)50004-9

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