Consciousness (Cognitive Science and Philosophy)

Reference entry · last updated September 5, 2026

Consciousness is the state of subjective qualitative experience, awareness of internal and external stimuli, and executive availability of information for reasoning, planning, and verbal report.[1] In philosophy of mind and cognitive neuroscience, inquiry divides between empirical mechanisms explaining how neural circuits discriminate and report sensory inputs, and the foundational question of why physical neurobiological computation is accompanied by subjective experiential feeling.[2]

Philosophical taxonomy

Contemporary analysis relies on foundational distinctions established in twentieth-century philosophy of mind.

Access versus phenomenal consciousness

Ned Block established a formal taxonomy dividing conscious processing into two distinct dimensions:[1]

Phenomenal Consciousness (P-consciousness): The experiential, qualitative aspect of mental states, commonly designated as qualia (for example, the subjective redness of a rose or the felt agony of physical pain).
Access Consciousness (A-consciousness): The availability of mental representations for use in deliberate thought, speech generation, working memory manipulation, and motor execution.

The hard problem

David Chalmers formulated the distinction between the "easy problems" and the "hard problem" of consciousness.[2] The easy problems concern cognitive functions explainable through standard computational or neurobiological mechanisms, such as stimulus categorization, behavioral integration, verbal reportability, and attentional focus. The hard problem asks why these functional operations are accompanied by first-person inner experience rather than occurring completely in the dark, without qualitative presence.

Multiple drafts model

Daniel Dennett rejected the traditional assumption of a centralized locus of experience, a conceptual trap he labeled the "Cartesian Theater."[3] In the multiple drafts model, parallel streams of perceptual interpretations, narrative fragments, and motor intentions compete continuously across distributed neural coalitions. Consciousness does not consist of a privileged playback screen; rather, a representation becomes conscious when it wins transient narrative salience and triggers observable behavioral probes.

Neuroscientific theories

Empirical neuroscience investigates conscious states through measurable architectural frameworks.

Global Neuronal Workspace Theory

Originally formulated as a cognitive blackboard model by Bernard Baars and expanded neurobiologically by Stanislas Dehaene and Jean-Pierre Changeux, Global Neuronal Workspace Theory (GNWT) posits that sensory information remains unconscious when confined to modular, encapsulated cortical processors.[4] When sensory signals achieve sufficient intensity and attentional reinforcement, they trigger non-linear "ignition" across long-range excitatory frontoparietal networks. This ignition broadcasts the winning representation globally across specialized processors, making it accessible to working memory, motor control, and linguistic reporting systems.[5]

Integrated Information Theory

Developed by Giulio Tononi, Integrated Information Theory (IIT) begins with phenomenological axioms and derives mathematical conditions for conscious physical substrates.[6] Under IIT, consciousness corresponds to an intrinsic causal property of a system, quantified as Φ (phi). High Φ requires that a system generate more cause-effect information as an integrated whole than can be accounted for by the sum of its independent parts. Systems with high functional modularity or strictly feedforward connectivity exhibit minimal Φ regardless of computational complexity.

Recurrent processing theory

Victor Lamme proposes that initial feedforward sweeps through the visual cortex reflect unconscious perceptual extraction.[7] Conscious experience emerges when localized horizontal and feedback connections initiate recurrent reverberating loops within sensory cortex. Recurrent processing can sustain phenomenal perceptual experience even before signals ignite the broader frontoparietal workspace required for verbal reporting.

Relationship to attention

While historically treated as synonymous or coupled processes, cognitive neuroscience increasingly models attention and consciousness as dissociable mechanisms.[8] Attention operates as a selective routing filter that allocates finite representational capacity to priority targets. Experiments demonstrate that subjects can selectively attend to subliminal, masked stimuli that never enter conscious awareness, while top-down attentional suppression can occur without conscious perception of the filtered distractor.[8]

Clinical assessment and states of consciousness

Medicine evaluates consciousness across two orthogonal dimensions: wakefulness (arousal, mediated by the ascending reticular activating system in the brainstem) and awareness (content, mediated by frontoparietal and thalamocortical networks). Clinical conditions such as coma, unresponsive wakefulness syndrome, and minimally conscious states present dissociated combinations of arousal and awareness. Diagnostic innovations such as the Perturbational Complexity Index (PCI) deliver transcranial magnetic stimulation pulses to the cortex and measure the algorithmic complexity of evoked electroencephalographic responses to assess covert capacity for integrated experience.[9]

Artificial intelligence perspectives

Modern machine learning systems demonstrate high task competence across complex domains (linguistic reasoning, vision, strategic gameplay) through deep neural network inference. However, technical consensus distinguishes functional simulation of reasoning from conscious subjective awareness.[10] Stateless evaluation of static weights via matrix transformations processes informational tokens without continuous metabolic persistence, subjective qualia, or integrated causal feedback loops described by biological theories of consciousness.

References

^ Ned Block, "On a confusion about a function of consciousness," Behavioral and Brain Sciences, vol. 18, no. 2, 1995, pp. 227–247.
^ David J. Chalmers, "Facing up to the problem of consciousness," Journal of Consciousness Studies, vol. 2, no. 3, 1995, pp. 200–219.
^ Daniel C. Dennett, Consciousness Explained, Little, Brown and Company, 1991, pp. 101–138.
^ Bernard J. Baars, A Cognitive Theory of Consciousness, Cambridge University Press, 1988.
^ Stanislas Dehaene and Jean-Pierre Changeux, "Experimental and theoretical approaches to conscious processing," Neuron, vol. 70, no. 2, 2011, pp. 200–227.
^ Giulio Tononi, "An information integration theory of consciousness," BMC Neuroscience, vol. 5, no. 42, 2004.
^ Victor A. F. Lamme, "Why visual attention and awareness are different," Trends in Cognitive Sciences, vol. 7, no. 1, 2003, pp. 12–18.
^ Christof Koch and Naotsugu Tsuchiya, "Attention and consciousness: two distinct brain processes," Trends in Cognitive Sciences, vol. 11, no. 1, 2007, pp. 16–22.
^ Adenauer G. Casali et al., "A theoretically based index of consciousness independent of sensory processing and behavior," Science Translational Medicine, vol. 5, no. 198, 2013, p. 198ra105.
^ John R. Searle, "Minds, brains, and programs," Behavioral and Brain Sciences, vol. 3, no. 3, 1980, pp. 417–424.