What is consciousness?

How do you define your being? Consciousness is one of humanity’s oldest intellectual challenges. Not simply a philosophical exercise, scientists from neuroscience, psychology, and even artificial intelligence are actively working to define the nature of awareness, experience and self-awareness. Ultimately, consciousness is our capacity to experience the world around us through perception, sensation and thought. That subjective, first-person experience is also what is referred to as qualia — the ‘what it feels like’ to see red, hear music, etc. Although we are still far from fully understanding how the brain generates the richness of our inner lives, many theories have emerged that seek to address the fundamental nature of consciousness.

Subjective Experience

Ultimately, consciousness is about subjectivity. This is the “what it’s like” aspect of existence. Consider the flavor of coffee, the color red, or the sensation of pain. These are not merely factual descriptions of the world; they represent an experience that only you can have and describe from your unique vantage point. This subjective aspect is often referred to as qualia. So, for instance, when two people view a red apple, they agree that it is red, yet their subjective experience of “redness” could differ significantly depending upon whether they are experiencing normal vision or color blindness.

Because of this subjectivity, consciousness presents a nearly insurmountable challenge for scientific investigation. We can measure brain activity, observe behavioral manifestations and understand neuroanatomical connections, but we cannot access another person’s qualia. This is referred to as “the hard problem of consciousness.” David Chalmers introduced this concept in his 1995 paper titled “Facing Up to the Hard Problem of Consciousness.” The “easy problems” include understanding how the brain processes information, integrates perceptual data and influences behavior. The hard problem addresses why these processes result in subjective experience.

Neural Correlates of Consciousness

Although the hard problem remains unresolved, much progress has been achieved in identifying the neural correlates of consciousness (NCCs). NCCs refer to the minimum neural mechanisms and events necessary for a specific conscious experience. In essence, scientists are searching for patterns of brain activity associated with consciousness and/or awareness.

Studying patients who exhibit altered states of consciousness, including those in a vegetative or minimally conscious state, has contributed greatly to our understanding of NCCs. Researchers such as Adrian Owen have demonstrated that some patients in what appear to be vegetative states display brain activity indicative of awareness when asked to imagine specific scenarios such as playing tennis. Therefore, consciousness appears to exist independently of overt signs of responsiveness.

Functional Magnetic Resonance Imaging (fMRI) and Electroencephalography (EEG) are among the primary methods used to investigate NCCs. fMRI allows researchers to visualize which brain regions are activated and how they communicate when a person becomes aware of a stimulus — e.g., when a brief visual stimulus that was previously unnoticed flashes on a screen. Brain regions commonly activated during conscious perception include areas in the prefrontal cortex and parietal lobe as well as widespread distributed network activation.

Major Theories of Consciousness

There are numerous theories that aim to elucidate the nature of consciousness. Each theory has its strengths and limitations.

Global Workspace Theory (GWT)

Cognitive Psychologist Bernard Baars proposed the Global Workspace Theory (GWT), which suggests that consciousness emerges from a “global workspace” within the brain. The GWT views the global workspace as analogous to a central broadcasting system. The global workspace serves as a system where information processed by multiple specialized systems (perception, memory, emotion) can become globally available to all other parts of the brain. As long as information is contained in the global workspace, it is conscious. Using a metaphor based on theater lighting: what is in the spotlight (i.e., what is in the global workspace) is conscious; what lies off-stage is unconscious.

Integrated Information Theory (IIT)

According to Giulio Tononi’s Integrated Information Theory (IIT), consciousness is an intrinsic property of systems whose components are strongly connected and mutually influencing. Any system exhibiting a high level of integrated information is said to possess consciousness. IIT uses a mathematical quantity called phi (\Phi) to quantify consciousness. Systems possessing a higher phi-value (i.e., both highly integrated and highly differentiated) are viewed as being more conscious. Importantly, IIT predicts that non-biological systems (including artificial intelligent systems or complex computer networks) could potentially meet IIT’s criteria for high levels of integrated information and therefore achieve conscious experience.

Recurrent Processing Theory

Victor Lamme et al.’s Recurrent Processing Theory stresses the role that recurrent loops play in generating conscious experience. In addition to feed-forward sweeps triggered by sensory input, recurrent loops enable additional processing and enrichment of representations. Thus, for an item to reach conscious experience via sensory input, a second wave of processing activity (referred to as the “recurrent”) must follow the initial feed-forward processing activity.

Relationship Between Awareness/Attention and Consciousness

Awareness and attention are closely related but distinct concepts. Attention refers to our ability to selectively filter out extraneous stimuli and focus on relevant ones. Attention can either be directed volitionally (trying to listen to a particular conversation in a busy restaurant) or automatically (reacting quickly to a car stopping suddenly in front of you).

However, it would be incorrect to equate attention with consciousness. An animal can attend to something without being consciously aware of it. For example, a dog may react reflexively to hearing a siren without realizing it heard anything. Conversely, we can be conscious of something without focusing attention on it. For example, we may realize that we are wearing our favorite sweater although we did not pay deliberate attention to it.

Awareness/consciousness represents the broader context within which attention focuses on specific aspects of our environment.

Evolutionary Functionality of Consciousness

A major remaining question concerns why consciousness evolved in the first place. One possible reason is that consciousness provides an evolutionary benefit by enabling flexible adaptation to changing circumstances. If all our responses were strictly automatic, we would lack flexibility in response to novel situations and would likely fail to adapt effectively in unpredictable or dynamic environments. Consciousness may enable:

Flexible Decision-Making: beyond purely instinctual reactions.
Sophisticated Planning: thinking about potential future consequences.
Social Interaction: understanding other minds (theory of mind).
Learning/Memory: integrating past experiences.

In general terms, having a richer inner-world may offer an organism greater success navigating their environment, avoiding threats/predators, finding food and reproducing successfully. Being able to mentally anticipate future events or consider alternative outcomes offers an important survival advantage.

Ongoing Research into Consciousness

The study of consciousness continues to be an exciting and multi-disciplinary field of inquiry. Ongoing advances in imaging techniques for observing brain activity, developing computational models of brain function and continued investigations into disorders of consciousness continue to expand our knowledge regarding mechanisms underlying conscious experience. Whether we develop a unifying explanation for conscious experience or whether it turns out that consciousness is an emergent property too complexly constructed to be explained by any unified theory remains unknown at this time. Nonetheless, the journey to understand our own minds continues to capture the imagination of many scientists.

The “Hard Problem” defined above refers to explanations for why physical processes in the brain create subjective experience (“what it’s like” to be conscious); whereas easy problems concern explanations for how the brain accomplishes functions such as perception, memory and attention.

Are animals capable of experiencing conscious sensations?

There are many scientists and philosophers who argue that consciousness exists on a continuum and is not limited exclusively to humans. Many animals (especially mammals and some species of birds) demonstrate behaviors characteristic of subjective experience (emotions, awareness), supporting various theories of consciousness.

Where does consciousness reside in the brain?

Unlike attention or perception-consciousness is not localized to any single brain location. Rather, it seems that conscious experience arises from the integration of wide-spread brain networks engaged in reciprocal communication (partially including frontal-parietal-thalamic circuitry).

Will AI ever be conscious?

This question is currently under intense debate. Some theories (such as IIT) predict that AI could potentially be conscious if it reaches high-enough levels of integrated information (highly interconnected parts producing more information than their individual parts). Other theories stress biological or emergent features that may limit consciousness to living brains