How Can We Study Conscious Experience?
Experience, measurement, neural evidence, and competing explanations
- Level
- Intermediate
- Reading load
- 9 core readings in 5 units
- Prerequisites
- The Biological Psychology foundation or equivalent familiarity with neural recording, intervention, and psychological measurement. Circuits and Sleep provide useful preparation. The guides introduce consciousness terminology; specialist training in philosophy, imaging analysis, or clinical assessment is not assumed.
- Last reviewed
- September 2026
Introduction
A person sees a face, remembers a dream, or follows an instruction. Each response offers a way to investigate conscious experience, but what should we conclude when the person cannot respond? And when a brain signal changes, does it reflect the experience itself, the conditions that make experience possible, or the effort of reporting it? These questions make consciousness a problem of evidence as well as a subject of theory.
This path begins by asking whether different aspects of consciousness can be placed on a single scale. It then examines how researchers separate an experience from the processes of attending to it, remembering it, and describing it. A perceptual experiment and a brain-stimulation study show what different comparisons can establish. Neither a report nor a brain signal interprets itself.
The next readings compare theories and examine a collaboration in which researchers agreed on competing predictions before inspecting the results. The final unit brings the measurement problem back into view through dreaming and cases where ordinary responses are unavailable. Researchers look for evidence that a person can follow an instruction through brain activity, or study the complexity of the brain's response to stimulation. The question throughout is what these observations justify saying about experience.
By the end, you should be able to identify which aspect of consciousness a claim concerns, explain the assumptions behind its measurement, and judge whether a study distinguishes theories or leaves several explanations open. Some readings are demanding and may need several sittings; the guides connect their methods with the questions they are intended to answer.
Unit 1 of 5
Which aspect of consciousness is at issue?
Before comparing brain signals, clarify what would count as a difference in consciousness. A single score may be useful while leaving several capacities and kinds of experience unresolved. Treat the opening proposal as an argument to test throughout the path.
Reading
1 of 9Are There Levels of Consciousness?
Bayne, T., Hohwy, J., & Owen, A. M. (2016). Are there levels of consciousness? Trends in Cognitive Sciences, 20(6), 405–413. https://doi.org/10.1016/j.tics.2016.03.009
Foundational argument · Critical reappraisal · Moderate · Full work: 9 pages
Distinguish an experience's content from a person's global condition, and examine what an ordering of states assumes.
Why you’re reading it. Establish the conceptual question to which the later measures and theory tests must answer.
A question to consider. How would you compare a vivid dream with mild sedation without deciding in advance that one must be more conscious?
Unit 2 of 5
How can experience be measured?
A difference between reported experiences can include differences in attention, memory, and action. First identify that problem in a methodological argument, then examine an experiment that changes reporting requirements. Ask what the new comparison resolves and what its indirect readout assumes.
Reading
2 of 9Distilling the Neural Correlates of Consciousness
Aru, J., Bachmann, T., Singer, W., & Melloni, L. (2012). Distilling the neural correlates of consciousness. Neuroscience & Biobehavioral Reviews, 36(2), 737–746. https://doi.org/10.1016/j.neubiorev.2011.12.003
Methodological contribution · Critical reappraisal · Challenging · Full work: 10 pages
Track the distinction between experience, enabling conditions, and consequences rather than assigning each a fixed moment in time.
Why you’re reading it. Develop a framework for interpreting the neural contrasts used throughout the remaining readings.
A question to consider. If a signal predicts a seen stimulus before it appears, what role could it have and what experiment would distinguish that role from a consequence of seeing?
Reading
3 of 9Binocular Rivalry: Frontal Activity Relates to Introspection and Action But Not to Perception
Frässle, S., Sommer, J., Jansen, A., Naber, M., & Einhäuser, W. (2014). Binocular rivalry: Frontal activity relates to introspection and action but not to perception. The Journal of Neuroscience, 34(5), 1738–1747. https://doi.org/10.1523/JNEUROSCI.4403-13.2014
Methodological contribution · Landmark empirical study · Challenging · Full work: 10 pages
Compare active report, passive viewing, and physical replay, including the calibration of eye-based measures.
Why you’re reading it. Apply Aru and colleagues' framework to a concrete attempt to reduce report-related activity.
A question to consider. If a frontal difference disappears without button reports, what must you know about attention and the eye-based readout before interpreting that disappearance?
Unit 3 of 5
Which neural changes are relevant?
Recording an association and changing a percept through stimulation support different inferences. Use the single-patient case to assess controls and causal scope. A causal contribution may still involve a network, an enabling process, or only one feature of experience.
Reading
4 of 9Electrical Stimulation of Human Fusiform Face-Selective Regions Distorts Face Perception
Parvizi, J., Jacques, C., Foster, B. L., Witthoft, N., Rangarajan, V., Weiner, K. S., & Grill-Spector, K. (2012). Electrical stimulation of human fusiform face-selective regions distorts face perception. The Journal of Neuroscience, 32(43), 14915–14920. https://doi.org/10.1523/JNEUROSCI.2609-12.2012
Landmark empirical study · Methodological contribution · Moderate · Full work: 6 pages
Trace the argument from face-selective recording to stimulation and the reported change in appearance.
Why you’re reading it. Add intervention evidence to the earlier correlational comparisons without treating any perturbation as a complete mechanism.
A question to consider. Which result distinguishes a causal contribution from a correlate, and which further comparison would be needed to establish that the stimulated site is necessary?
Unit 4 of 5
What do competing theories predict?
A useful theory specifies what it explains and what observations would count against it. Compare several families before examining one negotiated test of two accounts. Keep the underlying theory, an agreed prediction, its measurement, and the interpretation of a result distinct.
Reading
5 of 9Theories of Consciousness
Seth, A. K., & Bayne, T. (2022). Theories of consciousness. Nature Reviews Neuroscience, 23(7), 439–452. https://doi.org/10.1038/s41583-022-00587-4
Major synthesis · Foundational argument · Challenging · Full work: 14 pages
Compare explanatory targets as well as mechanisms, especially experience, access, and particular contents.
Why you’re reading it. Make the alternatives intelligible before evaluating the adversarial study; the two tested theories do not exhaust the field.
A question to consider. Choose one prediction shared by two theories and explain why confirming it would leave their disagreement unresolved.
Reading
6 of 9Adversarial Testing of Global Neuronal Workspace and Integrated Information Theories of Consciousness
Cogitate Consortium, Ferrante, O., Gorska-Klimowska, U., Henin, S., Hirschhorn, R., Khalaf, A., Lepauvre, A., Liu, L., Richter, D., Vidal, Y., Bonacchi, N., Brown, T., Sripad, P., Armendariz, M., Bendtz, K., Ghafari, T., Hetenyi, D., Jeschke, J., Kozma, C., … Melloni, L. (2025). Adversarial testing of global neuronal workspace and integrated information theories of consciousness. Nature, 642(8066), 133–142. https://doi.org/10.1038/s41586-025-08888-1
Contemporary update · Methodological contribution · Challenging · Full work: 10 pages
Follow how predictions about content, duration, and connectivity become measurable criteria across methods.
Why you’re reading it. Evaluate a direct theory comparison alongside the earlier concerns about report, prerequisites, and consequences.
A question to consider. Choose one challenged prediction: what observation would help distinguish a failure of the theory from a failure of an auxiliary assumption about task or measurement?
Unit 5 of 5
What do altered states and difficult cases test?
Return to the opening distinctions under three different evidential conditions: a retrospective dream report, a covert response to an instruction, and a neural response requiring no voluntary task. These approaches address different questions. Compare the meaning of positive evidence and of an absent response without turning any single measure into a universal verdict.
Reading
7 of 9The Neural Correlates of Dreaming
Siclari, F., Baird, B., Perogamvros, L., Bernardi, G., LaRocque, J. J., Riedner, B., Boly, M., Postle, B. R., & Tononi, G. (2017). The neural correlates of dreaming. Nature Neuroscience, 20(6), 872–878. https://doi.org/10.1038/nn.4545
Landmark empirical study · Methodological contribution · Challenging · Full work: 7 pages
Compare experience reports within sleep stages and examine the role of remembering after awakening.
Why you’re reading it. Test whether physiological state, experience, and report can be separated when external stimulation and ongoing tasks are reduced.
A question to consider. What does an experience-without-content-recall report add to the comparison, and why does it not eliminate every memory explanation?
Reading
8 of 9Willful Modulation of Brain Activity in Disorders of Consciousness
Monti, M. M., Vanhaudenhuyse, A., Coleman, M. R., Boly, M., Pickard, J. D., Tshibanda, L., Owen, A. M., & Laureys, S. (2010). Willful modulation of brain activity in disorders of consciousness. New England Journal of Medicine, 362(7), 579–589. https://doi.org/10.1056/NEJMoa0905370
Landmark empirical study · Methodological contribution · Moderate · Full work: 11 pages
Distinguish following an instruction through imagery from merely reacting to a sound, then examine the requirements of a successful response.
Why you’re reading it. Contrast positive evidence of covert cognitive activity with the ambiguity of nonresponse, extending both the report and state distinctions.
A question to consider. Why could a positive imagery response support awareness while a negative response fail to establish its absence?
Reading
9 of 9A Theoretically Based Index of Consciousness Independent of Sensory Processing and Behavior
Casali, A. G., Gosseries, O., Rosanova, M., Boly, M., Sarasso, S., Casali, K. R., Casarotto, S., Bruno, M.-A., Laureys, S., Tononi, G., & Massimini, M. (2013). A theoretically based index of consciousness independent of sensory processing and behavior. Science Translational Medicine, 5(198), Article 198ra105. https://doi.org/10.1126/scitranslmed.3006294
Methodological contribution · Landmark empirical study · Challenging · Full work: 10 pages
Separate the rationale for perturbational complexity from its calibration and its application to uncertain cases.
Why you’re reading it. Compare a measure that requires no voluntary task with Monti's command-following method, then return to Bayne's challenge to a single scale.
A question to consider. How could a scalar index be useful for detecting capacity while leaving the multidimensional argument intact?
Scope and omissions
This path studies human conscious experience through conceptual arguments, perceptual comparisons, neural intervention, theory testing, and altered states. Vision supplies most content-specific evidence; dream reports and heterogeneous clinical cases broaden the circumstances but do not establish generality across every sensory modality or population.
It does not provide a complete philosophy of mind, a clinical diagnostic protocol, or a catalogue of altered states. Animal and infant consciousness, self-consciousness, meditation, psychedelics, and artificial consciousness require further work beyond this path. The absence of a behavioral response is not a conclusion about personhood, and the scientific comparisons here do not determine individual clinical decisions.
Synthesis
The study of consciousness advances when the intimacy of experience meets the discipline of a precise question. Reports, interventions, and complexity measures illuminate different aspects of the problem. Agreement among them can strengthen an inference, while leaving their meanings distinct. The task is to show what each observation warrants and which competing explanations it can help us distinguish.
Choose a result from the perceptual or altered-state studies. State exactly what was observed, which aspect of consciousness is inferred, and two explanations compatible with the observation. Propose one comparison that would distinguish those explanations. Describe what both a positive and a negative outcome would leave unresolved. Then explain whether your proposal concerns particular contents, cognitive access, or a broader capacity for experience.
Return to the contrast between Bayne's multidimensional account and Casali's scalar index. Can a measure be useful without representing the whole phenomenon on one axis? Specify an empirical finding that would make your answer stronger.
For a closer examination of recording and intervention, continue with How Do Neural Circuits Turn Sensation into Action?. For the regulation and physiology of sleep states, follow How Do Biological Rhythms Organize Sleep and Waking?.
To distinguish a capacity's present role from its evolutionary history, compare species, and examine how development and culture enter an evolutionary explanation, follow How Does Evolution Help Explain Behavior?.
Further reading
Optional. Not part of the core sequence.
- Naccache, L., Sergent, C., Dehaene, S., Wang, X.-J., Farisco, M., & Changeux, J.-P. (2025). GNW theoretical framework and the “adversarial testing of global neuronal workspace and integrated information theories of consciousness”. Neuroscience of Consciousness, 2025(1), Article niaf037. Paper. Presents a response from GNWT proponents concerning the tested predictions and their interpretation; compare it with the consortium's preregistered rationale. Open article.
- Dehaene, S., & Changeux, J.-P. (2011). Experimental and theoretical approaches to conscious processing. Neuron, 70(2), 200–227. Paper. Develops the global neuronal workspace account in greater theoretical and empirical depth.
- Tononi, G., Boly, M., Massimini, M., & Koch, C. (2016). Integrated information theory: From consciousness to its physical substrate. Nature Reviews Neuroscience, 17(7), 450–461. Paper. Develops IIT's commitments and connection to physical systems beyond the comparative review.
- Ruby, P. M. (2020). The neural correlates of dreaming have not been identified yet. Commentary on “The neural correlates of dreaming. Nat Neurosci. 2017”. Frontiers in Neuroscience, 14, Article 585470. Paper. Offers an explicit objection concerning retrospective dream reports, recall, and interpretation of neural associations.
- Bodien, Y. G., Allanson, J., Cardone, P., Bonhomme, A., Carmona, J., Chatelle, C., Chennu, S., Conte, M., Dehaene, S., Finoia, P., Heinonen, G., Hersh, J. E., Kamau, E., Lawrence, P. K., Lupson, V. C., Meydan, A., Rohaut, B., Sanders, W. R., Sitt, J. D., … Schiff, N. D. (2024). Cognitive motor dissociation in disorders of consciousness. New England Journal of Medicine, 391(7), 598–608. Paper. Extends covert command-following to a larger multisite sample; examine recruitment, differing methods, and false negatives. Author manuscript.
- Casarotto, S., Comanducci, A., Rosanova, M., Sarasso, S., Fecchio, M., Napolitani, M., Pigorini, A., Casali, A. G., Trimarchi, P. D., Boly, M., Gosseries, O., Bodart, O., Curto, F., Landi, C., Mariotti, M., Devalle, G., Laureys, S., Tononi, G., & Massimini, M. (2016). Stratification of unresponsive patients by an independently validated index of brain complexity. Annals of Neurology, 80(5), 718–729. Paper. Extends the validation of perturbational complexity and separates calibration from application to uncertain cases. Open article.