The Status and Future of Consciousness Research

The Status and Future of Consciousness Research Overgaard

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The Status and Future of Consciousness Research 2017 Frontiers in Psychology 10.3389/fpsyg.2017.01719 Overgaard2017-the-status-and-future-of-consciousness-resea Overgaard2017-the-status-and-future-of-consciousness-resea.txt, the project's staged copy 385a9d64bb368bf16c2c580b60cc408b040dd629 not-redistributable neuroscience

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61 spans located by searching the stored text for the quote's exact words, allowing any whitespace between them The two entangled obstacles of consciousness research - how to measure consciousness, and what counts as a neural correlate of it. critique measurement of consciousness and its neural correlates reviewreview mechanismsAny objective measure must be calibrated against something already known to track consciousness, and that anchor is a subjective report - so the weaknesses of introspection are re-imported into every objective method mechanismsObjective measures work only under an unstated assumption that the threshold for a correct response coincides with the threshold for having the experience, which is what makes them fallible as measures of awareness mechanismsEmpirical consciousness science arose less from new neuroscience technology than from an openness that let philosophical, cognitive and neuroscientific questions, methods and arguments be integrated The two obstacles are one problem: you cannot look for the correlates of something without first fixing how you will measure it An objective measure has to be calibrated against something, and the only available something is a subjective report - so the weaknesses it was designed to avoid come back in through the calibration No-report paradigms do not escape this, because associating a behavioural marker with experience in the first place requires introspection Objective measures also assume the threshold for a correct response coincides with the threshold for experiencing the content, which is an assumption and not a finding One proposed resolution of the prefrontal-versus-occipital dispute is that both are right about different things, because there are two kinds of consciousness Existing evidence cannot adjudicate the metaphysical question, because it fits every position equally The paper explicitly presents its list of challenges as a selective sample rather than a complete survey of the field's problems.what this limits: the list of challenges itself: THEY OBVIOUSLY ONLY REPRESENT A FEW OF THE MANY SCIENTIFIC AND THEORETICAL ISSUES THAT SCIENTISTS IN THIS AREA FACE The field's central term is used without its ambiguity being examinedwhat this limits: every NCC result in the field: IT IS RARELY DEBATED WHAT WE MEAN WITH A NEURAL CORRELATE OF CONSCIOUSNESS, while MOST EXPERIMENTS AIM TO IDENTIFY THE MINIMAL NEURAL ACTIVATIONS THAT ARE SUFFICIENT FOR A SPECIFIC CONTENT OF CONSCIOUSNESS There is still no universally accepted measure of the thing being studiedwhat this limits: any quantitative claim about consciousness: WE STILL HAVE NO UNIVERSALLY ACCEPTED MEASURES OF CONSCIOUSNESS The patient comparisons that would settle levels of consciousness are confounded by lesion variability and reorganisationwhat this limits: the patient comparisons: MOST BRAIN INJURED PATIENTS HAVE MANY DIFFERENT LESIONS AND, CONSEQUENTLY, MASSIVE REORGANIZATION, WHICH MAKES COMPARISONS VERY DIFFICULT Some patients classified as unconscious appear not to be, so the contrast group is unreliablewhat this limits: the unconscious contrast group: SOME EXPERIMENTS INDICATE THAT NOT ALL SUCH PATIENTS ARE UNCONSCIOUS The label 'no-report paradigm' names nothing new, since every purely objective paradigm is already without reportwhat this limits: the no-report label: ALL PARADIGMS USING OBJECTIVE MEASURES ONLY ARE WITHOUT REPORT, SO IN A CERTAIN SENSE, PARADIGMS LABELED NO-REPORT PARADIGMS HAVE NOT INTRODUCED ANYTHING NEW neural correlate of consciousness - of CONTENT: the minimal activations sufficient for one specific conscious content neural correlate of consciousness - AS SUCH: what distinguishes being awake from asleep or dead, not tied to any content measuring consciousness - DIRECT: the subject reports their own experience, with the known limits of self-report measuring consciousness - INDIRECT: performance on a task stands in for experience, which avoids self-report and imports a threshold assumption instead early activations - as the correlate of phenomenal consciousness, which is the currently favoured reading early activations - as PRECONSCIOUS: information not yet conscious, which is the opposite reading of the same data claim_type: critiquea second reading reaching the same value. Recorded: critique — note: a second reading reaching the same value from a different sentence. Not applied - a person decides. phenomenon: measurement of consciousness and its neural correlatesa second reading reaching the same value. Recorded: measurement of consciousness and its neural correlates — note: a second reading reaching the same value from a different sentence. Not applied - a person decides. builds-on → Overgaard and Fazekas (2016) critiques → no-report paradigms as a solution to the measurement problem critiques → the position that objective measures alone can settle questions about consciousness supports → Block's two-correlates proposal as a reading of the prefrontal/occipital dispute extends → the REF-CON model, on which there need be no universal correlate at all subjective report —contrasted-with→ objective measuresstrength of the relation: 1subjective reportobjective measures no-report paradigms —same-as→ objective measuresstrength of the relation: 0.9 Audit 2026-09-28: DOUBTFUL - read against its span and kept, but the span says 'in a certain sense' no-report paradigms are objective ones; same-as is hedged.no-report paradigmsobjective measures phenomenal consciousness —distinct-from→ access consciousnessstrength of the relation: 1 Audit 2026-09-28: DOUBTFUL - read against its full span and kept, but Block 'ARGUES there MAY be' two correlates, for phenomenal and access consciousness; distinct-from is attributed and hedged.phenomenal consciousnessaccess consciousness preconscious —distinct-from→ consciousnessstrength of the relation: 0.9preconsciousconsciousness contrastive analysis —operationalised-as→ vegetative statestrength of the relation: 0.9 Audit 2026-09-28: DOUBTFUL - read against its span and kept, but vegetative patients are one contrast group; operationalised-as is the wrong type.contrastive analysisvegetative state neural correlate of consciousness —distinct-from→ mind-brainstrength of the relation: 1 · note: DOUBTFUL, found by an audit that read the edge against its span: hedged metaphysical distinction. The edge is kept live; a reader should weigh it with this in mind. Audit 2026-09-28: DOUBTFUL - read against its full span and kept, but the span says evidence of a correlate does not settle whether consciousness is identical to brain activity; distinct-from is loose.neural correlate of consciousnessmind-brain The field's two dominant problems are not independent: neural correlates cannot be identified without first committing to a measure of consciousness, so the measurement problem is prior to the correlate problem. Objective (indirect) measures cannot escape the weaknesses of introspective report, because calibrating any objective measure requires pairing a behaviour with a subjective report in the first place. So-called no-report paradigms introduce nothing that escapes introspection either, since the link between the objective marker and conscious experience can only be established by direct introspective report. Different measurement methods seem to generate different answers about the neural correlates of consciousness: some yield prefrontal correlates of visual consciousness, others occipital/parietal correlates without prefrontal involvement. Most recent reviews lend support to the view that consciousness is associated with occipital/parietal rather than prefrontal activity. Existing consciousness data seem to fit easily into every theory of the mind-brain relation. The author names measuring consciousness "from the outside" as one major future challenge. Despite these unsolved foundations, consciousness research already works as a discipline producing meaningful and reproducible results. different methods of measuring consciousness yield different conclusions about which brain regions are its correlates recent reviews favour the occipital/parietal reading over the prefrontal one the same early activations are read as the correlate of consciousness by one camp and as preconscious by the other the existing evidence seems to fit every metaphysical position the field has proven able to produce meaningful and reproducible results neural correlates of consciousnessneural correlates of consciousness neural correlates of consciousnessneural correlates of consciousness direct approachdirect approach indirect approachindirect approach no-report paradigmno-report paradigm REF-CON model of consciousnessREF-CON model of consciousness neural correlate of consciousnessneural correlate of consciousness consciousness as suchconsciousness as such no-report paradigmsno-report paradigms REF-CON modelREF-CON model

The Status and Future of Consciousness Research

Morten Overgaard Morten Overgaard

1 Cognitive Neuroscience Research Unit (CNRU), CFIN, Institute of Clinical Medicine, Aarhus University, Aarhus, Denmark

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1 Cognitive Neuroscience Research Unit (CNRU), CFIN, Institute of Clinical Medicine, Aarhus University, Aarhus, Denmark

Edited and reviewed by: Axel Cleeremans, Free University of Brussels, Belgium

✉ *Correspondence: Morten Overgaard mortover@rm.dk

This article was submitted to Consciousness Research, a section of the journal Frontiers in Psychology

Received 2017 May 23; Accepted 2017 Sep 19; Collection date 2017.

Keywords: consciousness, consciousness disorders, measures of consciousness, neural correlates of consciousness, artificial consciousness

This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) or licensor are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.

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PMCID: PMC5641373 PMID: 29066988

As papers about consciousness are so often introduced, consciousness was until few decades ago considered a philosophical problem only, and the current interest in empirical consciousness research was unforeseen. This development was of course influenced by the technological advancements in neuroscience during those decades, but more important and fundamental was a new openness to interdisciplinary integration of research questions, methods and arguments. Cognitive scientists and neuroscientists agreed that the philosophical problems of why and how there is consciousness are also their problems. Philosophers agreed that empirical evidence may resolve or at least influence this debate. Scientists across disciplines generally agree that consciousness is subjective, characterized by a kind of privileged first-person access.

Consciousness research has proven to be an actual and functioning discipline able to provide meaningful and reproducible results. Nevertheless, it has yet only scratched the surface in the attempt to solve some its bigger challenges, e.g., its many underlying questions of metaphysics (i.e., why does consciousness exist?) and questions of mechanisms (how does consciousness exist?).

One major obstacle for consciousness research is the lacking consensus of how to optimally measure consciousness empirically. Another major challenge is how to identify neural correlates of consciousness. This challenge clearly relates to the first as one needs to apply a measure of consciousness in order to identify its correlates. Current consciousness research is already occupied with these questions that may even be said to dominate the scientific debate.

As it will be argued below, consciousness research may face problems in the future that are currently less debated but which are logical extensions of the challenges above. It is a natural ambition when developing a measure of consciousness to be able to determine whether non-reporting subjects or even machines are conscious and of what. And it is a natural ambition when finding neural correlates of consciousness to understand how these correlates relate to a deeper metaphysical understanding of the relation between subjective experience and the physical substrate of the brain.

How do we measure consciousness?

Historically, the attempt to “measure” consciousness has unfolded as a debate between direct and indirect approaches. Direct approaches, at least intuitively, are the most informative as participating experimental subjects here simply report about their own experiences. As subjective reports however have demonstrable limits (e.g., lack of insights into personal bias, memory problems etc.), many scientists have refrained from their use and insisted on the use of objective measures only (e.g., Nisbett and Wilson, 1977 ; Johansson et al., 2006 ).

Experiments on consciousness that are based on objective measures—the “indirect” approach—typically involve asking subjects to choose between alternatives, e.g., in forced-choice tasks. Although such methods may stay clear of classical limitations of subjective methods, they are confronted with other problems, which, according to some scientists, are greater. For one thing, objective measures must assume that the “threshold” of giving a correct response is the same as the “threshold” of having a subjective experience of the same content (Fu et al., 2008 ; Timmermans and Cleeremans, 2015 ). Furthermore, in order to arrive at any one particular objective method, one must have “calibrated it” to something else in order to know that this particular behavior can be considered a measure of consciousness—and not something else. This would typically involve associating a subjective report with a particular behavior—a process by which one would “import” all the weaknesses related to subjective reports that one tried to avoid in the first place (Overgaard, 2010 ).

Proponents of the “direct” approach have attempted to develop precise and sensitive scales to capture minor variations in subjective experience, e.g., the Perceptual Awareness Scale and gradual confidence ratings (Ramsøy and Overgaard, 2004 ; Sandberg and Overgaard, 2015 ). Although different approaches to this idea disagree about what consistutes the optimal measure (Dienes and Seth, 2010 ; Timmermans et al., 2010 ; Szczepanowski et al., 2013 ), they share the view that a detailed subjective report may be imprecise yet better than an indirect measure.

In recent years, the arsenal of indirect measures have been supplied with what is named “no-report paradigms.” Essentially, all paradigms using objective measures only are without report, so in a certain sense, paradigms labeled “no-report paradigms” have not introduced anything new. Nevertheless, experiments of this kind attempt first to associate a particular objective measure (e.g., a behavior or a brain activation) with conscious experience, and then to apply this measure as a measure of consciousness so that no direct report is needed (e.g., Frässle et al., 2014 ; Pitts et al., 2014 ). Such methods intuitively seem to circumvent some of the criticism mentioned above. However, and as mentioned above, the only way one may associate a phenomenon as nystagmus with conscious experience is by the direct use of introspection (to establish the “correlation”) (Overgaard and Fazekas, 2016 ).

It has been proposed that the best and most practical way forward is to combine methods and learn what we can from the results we get (Tsuchiya et al., 2016 ). Whereas this is most likely what is necessary, it is important to notice that different methods seem to generate different results, so that some methods are associated with the finding that the neural correlates of visual consciousness involve prefrontal activity, whereas other methods are associated with the finding that visual consciousness mainly involve occipital/parietal activity but not prefrontal.

Neural correlates of consciousness

Most neuroscientific research on consciousness has had the explicit aim to identify the neural correlates of consciousness. Although it is rarely debated what we mean with a “neural correlate of consciousness,” most experiments aim to identify the minimal neural activations that are sufficient for a specific content of consciousness (Chalmers, 2000 ). Contrary to this, other scientists are preoccupied with finding neural correlates of consciousness “as such”—i.e., neural correlates that mark the difference between being dead, asleep, awake, etc., and which are not content-specific in the sense above.

With regards to the attempt to isolate neural correlates of conscious content, one central debate in recent years has been whether neural correlates of consciousness should primarily be associated with prefrontal cortex (“late” activations) or whether (visual) consciousness should be associated with occipital/parietal activations (“early” activations). According to most recent reviews and articles, evidence is lending support toward the latter view (Andersen et al., 2016 ; Koch et al., 2016 ; Hurme et al., 2017 ). According to this view, “late” activations are not actual correlates of consciousness, but are confounds associated with metacognition and report (e.g., Aru et al., 2012 ). Nevertheless, proponents of the opposite view—that consciousness is associated with prefrontal cortex activity—argue that “early” activations in fact represent preconscious states—i.e., information that is not yet conscious (e.g., Lau and Rosenthal, 2011 ).

According to other perspectives, this debate is partially misunderstood. Block ( 2005 ) argues that there may be two neural correlates of consciousness: One relating to phenomenal consciousness (the “early” activations), and one relating to access consciousness (the “late” activations). Others suggests that there is an identity between subjective experience and certain causal properties of physical systems rather than an identity between experience and particular brain parts (Tononi et al., 2016 ). According to the REF-CON model of consciousness, subjective experience is intrinsically related to a particular kind of “strategy” that makes information available for action (Overgaard and Mogensen, 2014 ; Mogensen and Overgaard, 2017 ). From this perspective, there need not be any “universal” correlate of consciousness at all. But even in such theoretical models according to which finding neural correlates of consciousness is very different from explaining consciousness, neural correlates of consciousness are essential as evidence to show how and if they work in practice.

There has been relatively more research into the neural correlates of the contents of consciousness than into “consciousness as such.” Research attempting to identify particular “levels” of consciousness obviously also face many methodological challenges, not least relating to contrastive analysis. Some studies have attempted to contrast healthy subjects with patients in vegetative state or minimally conscious state (Boly et al., 2013 ), although there are a number of problems: Some experiments indicate that not all such patients are unconscious (Owen et al., 2006 ), and—at the same time—most brain injured patients have many different lesions and, consequently, massive reorganization, which makes comparisons very difficult.

The future challenges

The “upsurge” of interest in a science of consciousness did not begin but certainly took off with the publications of Chalmers ( 1995 , 1996 ) and the Tucson-based conference series “Toward a Science of Consciousness”—soon to be further strengthened by the annual conferences organized by the ASSC (Association for the Scientific Study of Consciousness). Since then, much has happened in the attempt to discover neural and cognitive correlates of consciousness. It is however as uncertain today as it was then how exactly to apply these findings. In principle, there are many potential applications of consciousness research, but whereas some are extensions of the more fundamental questions (e.g., ethics and law), others are close to the heart of what consciousness research is (arguably) about, i.e., the mind-brain or mind-body problem.

One such fundamental problem relates to the fact that consciousness is subjective and in this way accessible from the first person only. Whereas we still have no universally accepted measures of consciousness, much progress has been made with regards to how one may grasp the content of an experience in the context of an experiment. One major future challenge will be how to measure consciousness “from the outside.” This problem is currently being faced in coma and vegetative state patients who either do not respond or respond in a minimal or strange fashion. It will very likely be an even greater challenge for a future science of consciousness to consider how to evaluate whether artificial systems (e.g., computers or robots) can be conscious or whether experience is a privilege for biological creatures. Essentially, these questions force us to try to make scientifically based decisions about how to measure conscious experience in highly different situations: In coma/vegetative state patients, there are little or no responses, yet a neural (however altered) system. In artificial systems, there may be high responsiveness (even, in principle, explicit expressions of being conscious) but no neural (biological) system.

One possibly even greater challenge will be to reintegrate the philosophical metaphysical debate into the scientific work. It will be a challenge to the future science of consciousness to demonstrate that empirical work on consciousness directly aids an understanding of the fundamental questions about consciousness. This challenge may seem unavoidable as the current preoccupation with cognitive functions and neural activations associated with subjective experience in most cases seems so directly linked to and motivated by the mind-brain problem. Existing data, however, seems to fit easily into every theoretical understanding of this problem. In and of itself, it seems not to be the case that evidence that perceptual experience is associated with—say—activity in primary visual cortex also provides evidence to determine whether consciousness should be seen as—say—identical to or metaphysically different from brain activity. Accordingly, it will require something “extra” to answer this challenge. Either, if possible, experimental investigations must be designed in order to “test” theoretical positions that currently are stated within the framework of philosophy of mind. Alternatively, experimental consciousness research must work even closer with theoretical consciousness research in order to make empirical data available as arguments.

Future directions

The challenges highlighted above obviously only represent a few of the many scientific and theoretical issues that scientists in this area face. Consciousness remains one of the biggest scientific challenges among all disciplines as the most fundamental questions are not simply unanswered—it is still highly unclear how one should even begin to answer them.

Currently, consciousness research is often considered a “topic”—or even “niche”—under the umbrella of cognitive neuroscience. Nevertheless, consciousness researchers often point out that subjective experience is the underlying and fundamental reason for many questions in neuroscience. Scientists interested in the brain are often seeking answers to questions such as why we become addicted, how we remember, perceive, or solve problems. Such questions arguably presume conscious experience and make little sense without. Terms such as “memory” or “perception” do not solely refer to behavior, but also to particular kinds of conscious content which we know about from introspection. For this reason, one future ambition for consciousness research could be to become a more integral part of the overall ambition to understand the brain, and as such become part of the basic curriculum for any neuroscientist.

Author contributions

The author confirms being the sole contributor of this work and approved it for publication.

Conflict of interest statement

The author declares that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.