Toward a Science of Consciousness VI: MAPS Members’ Views on Consciousness and Psychedelics

Summer 2004 Vol. 14, No. 1 10 Stamps and $250,000

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Editor’s note: While MAPS usually does not devote so much space to a conference report, we have chosen to include the following pieces that are primarily inspired by, rather than written about, the "Toward a Science of Consciousness" conference, held in Tucson, Arizona, April 7-11, 2004. Alex Gamma writes about the philosophical debates surrounding consciousness, while Dan Potthast and Tim Butcher focus on the role of psychedelics in consciousness research.

The Problem of Consciousness by Alex Gamma

Different people mean different things when they talk about consciousness. This is the first thing to realize if you’re going to have a minimally fruitful discussion about the topic. Those friendly, spiritu- ally-oriented folks from the “psychedelic community” probably have something different in mind when they talk about expanding con- sciousness than philosophers or scientists talking about the C- word. In fact, the former are using the word in a loose sense, probably referring to the mind as a whole, including one’s sensory experiences, emotional feelings, thoughts, beliefs, and so on. Philosophers make finer distinctions. David Chalmers, head of the Center for Consciousness Studies in Tucson and one of the leading figures in the philosophy of mind, distinguishes between a core notion of consciousness, and a cluster of functions (e.g. visual discrimination, memory, learning, speech production, etc.) associated with it. The core notion is consciousness in the sense of qualitative, phenomenal experience: the fact that your conscious experiences feel a certain way, or that it is like something to have them. If you think of the blueness of the sky (so different from the redness of a ripe tomato), or the particular way a certain pain feels (a bee sting-ouch!), you know what I’m talking about. These phenomenal qualities of conscious- ness have been given the name “qualia.”

Chalmers argues that the core notion of conscious- ness, qualia, constitute the “hard problem” of conscious- ness, while the associated functions constitute (relatively) “easy problems.” The associated functions present “easy” problems because they are, in principle, easy to explain. How is information memorized? Or how is it learned? How can it be verbally expressed? We can give entirely satisfying scientific explanations for these functions by specifying causal brain mechanisms that perform the functions. Consider verbal report, for example. You look at a tree and tell me it’s blooming. We can give an account of how light waves travel from the tree to your eyes, stimu- late the photoreceptors in your retina, where neural impulses are generated and propagated along the optical nerve to the visual cortex in the back of your brain. There, the visual scene of the tree in front of you is analyzed, and features such as size, shape, and color of the various elements in the scene are extracted. This information is passed on to more frontal parts of the brain where the elements of the scene are identified as particular objects (“that’s a branch,” “those are blossoms”). This information, in turn, will be passed on to the speech production center in your left brain hemisphere, where it is transformed into motor commands that appropriately stimulate the muscles in your voice box, making you utter the words, “This tree is blooming.” Of course, the full story would include many more details, but we have no doubts that these could be supplied, once enough research has been performed. All of this can be explained purely in terms of physics, neurobiology, and information-processing. Nowhere in this account is there a need to refer to qualia, to the phenomenal quality of the visual scene you experience. And that’s the hard problem of consciousness: to explain why and how phenomenal consciousness enters the picture. Why are qualia associated with the various information-processing functions of the brain? How are they generated in the brain? It seems kind of surprising and strangely unnecessary that, over and above the causal flow of information in the brain, there is also an associated experience, a way that having the information feels. In recent years, neuroscientists have started taking the qualia issue seriously-or at least addressing it. The larger enterprise of that segment of neuroscience oriented towards consciousness has become the search for the neural correlates of consciousness (the so-called NCCs). These are the neural processes or states that underlie conscious, phenomenal states, which occur whenever we have a certain kind of phenomenal experience. Hunting NCCs is an important and respectable goal, and will tell us a lot about the way the brain works and what states might possibly generate qualia. But will it bring us closer to the solution of the hard problem of finding out how brain processes relate to or generate qualia? I can’t see how it would. No matter how much we know about which brain processes underlie qualia, it will still seem arbitrary that these processes are associated with any qualia at all, or with exactly these and not those qualia. (For example, why is a given brain state associated with the experience of redness and not blueness?)


Some speakers at the Tucson conference seemed to be untroubled by worries about the hard problem, and their presentations dealt with scientific details of neural or mental processes that are related to con- scious experience, without entering into discussions of the hard problem. Others, however, offered their takes on the hard problem. Susan Blackmore, a lecturer, writer and colorful figure in the field (literally, look at the first picture on http:// tucson6.html) emphatically argued that we are mistaken in our everyday beliefs about consciousness. She says that consciousness understood as a “continuous stream of rich and detailed experiences, happening one after the other to a conscious person” is an illusion. She does not deny that there is some sort of consciousness, she only claims that it is not the way it seems to us. How- ever, I’ve never heard her say just what she thinks consciousness really is like-i.e., what’s behind the illusion. She was quite clear on one thing, however: she answered the question whether there are qualia with a blunt “no.”

A similar stance is taken by the influen- tial American philosopher Daniel Dennett. He flatly denies the existence of qualia and thinks we all need some kind of psycho- therapy to exorcize the intuitions behind them. His usual strategy, which he also applied to the audience in Tucson, is to devise thought experiments to “pump” our intuitions away from qualia. Dennett states that the belief in qualia is the one persis- tent, but misguided, background assump- tion that has made the problem of con- sciousness seem intractable for centuries. If we can finally be cured of our belief, the problem will simply disappear.

Now if qualia are taken to be the phenomenal, qualitative aspects of consciousness, I don’t really know how to make sense of such pronouncements. Phenomenal consciousness is neither a belief, intuition, nor an assumption, it is simply an empirical fact of nature. All of us, at every moment of our waking lives, can confirm to ourselves that we are conscious, that it is like something for us to have sensory experiences, feelings, pains, and thoughts. So do Blackmore and Dennett deny that they have phenomenal experiences? I can’t really believe that’s what they want to say (after all, they’re human beings and I strongly suspect that they are indeed conscious).

Blackmore urges that if we patiently practice to look harder into ourselves-using meditation as one technique to do so-we become less and less sure about what’s in our consciousness at any given moment, until we finally realize that there are neither contents nor a stream of consciousness. There are at least two problems with this argument. First, it is certainly true that we can thin out the steady buzz of thoughts and sensations in our minds by practicing meditation, and that we might become unsure about aspects of the nature and timing of our conscious states. But this is a far cry from showing that whatever mental activity remains does not have any phe- nomenal, qualitative character. Do monks who have practiced meditation for decades cease to have some kind of phenomenal experience? If not, then there are still qualia. Second, even if meditation eventu- ally leads to a loss of qualia, it remains the case that at least I-as I am here now, not yet driven to unconsciousness by years of meditation-clearly have qualia.


Qualia won’t go away easily, it seems, and so we’re still faced with the hard problem. Chalmers’ own solution, though not presented explicitly in this conference, was a ghostly background presence in every corner of the conference locale. Chalmers argues that materialism/physicalism about consciousness (the view that phenomenal consciousness is a physical phenomenon, and that facts about phenomenal conscious- ness are entailed by physical facts) is false, and we need to expand the very basis of physics by adding consciousness as a new fundamental property to the universe, alongside known physical properties such as mass, charge and space-time. In this new scheme of things, we will have two primary kinds of stuff: physical stuff and phenom- enal stuff. This is a form of dualism, which is despised by most scientists, but which I assume not few of the readers of this article will find appealing. One implication of this view is that phenomenal properties are everywhere, not only in living beings with sophisticated nervous systems, but also in rocks, trees, and even atoms. These things don’t necessarily have full-blown conscious- ness as we experience it, but maybe some more basic, primitive, undifferentiated form of phenomenal experi- ence. This idea is not new, by the way. Under the name of “panpsychism” or “pan-experientalism” it has been floating around in philosophy throughout the ages. Dualism in this sense would solve the hard problem because it makes it unnecessary to explain how we can get from purely physical neural processes in the brain to phenomenal consciousness. Instead we put phenomenal consciousness into the picture from the very start, accept- ing it as a fundamental and irreducible part of reality. Of course, we still need an account of how these basic phenomenal properties get structured and organized into full-blown phenomenal experience, but there is little doubt that the story can be told, just as in the physical case, where we can tell a similar story. For example, the high-level biological structure or functions of the brain are built from interacting neurons, these in turn are built from proteins coded for by strands of DNA, these in turn are built from interacting bio-molecules, which in turn are built from interacting atoms, and so on. It’s an extremely complicated story, but we know that it can be told in principle.


Stephen Pinker, a Harvard psychologist and popular science writer, was invited to Tucson for a keynote address. Looking at consciousness from an evolutionary perspective, he made a distinction, very much in agreement with Chalmers’, between the causally describable functions associated with consciousness and its phenomenal core. He argued that all those functions of consciousness, for which we can in principle specify underlying causal brain mechanisms, might well be evolution- ary adaptations, but its phenomenal core- the qualia-cannot be because it has no causal effect. Only what is causally effective can be selected for by evolution, but qualia are not. So Pinker regards consciousness as an epiphenomenon without causal influ- ence on the physical world. This view might seem to put him into immediate trouble, since it makes it look impossible that we could ever know about and report on our conscious experience, if consciousness cannot affect the physical brain processes underlying knowledge formation and verbal report. However, Pinker thinks that our abilities to know and report our conscious experience are not based on causality, but on some other relation, which might be unique to consciousness.

Interestingly, the distinction between phenomenal consciousness and its associated causally describable functions does not lead Pinker to embrace dualism. Instead, he follows along the lines of the philosopher Colin McGinn who believes that consciousness is a perfectly normal physical phenomenon, but that we humans do not have the cognitive capacities to under- stand how it relates to the rest of the world. This thesis is known under the name of “cognitive closure.” It is based on the observation that all other animals have cognitive limitations that preclude them from ever understanding certain concepts. Your dog, for example, will never understand the principles of thermo- dynamics. So why should we humans be the only creatures without cognitive limita- tions? Like for other animals, there must exist concepts that are beyond our grasp, and McGinn argues that consciousness is one of these concepts. Some philosophers consider this stance defeatist and overly pessimistic, others have called it “mysterianism.” It seems like premature surrender. Indeed, there is a certain danger in extrapolating from a present failure to understand consciousness to an in-principle inability to do so. Dennett, for example, argued that the unique human ability to use language to entertain and evaluate a potentially infinite number of thoughts is the decisive difference that might untie us from the cognitive limitations other animals have. Still, given that so little progress has been made on the hard problem, I consider the cognitive closure hypothesis at least a respectable philosophical position. *


Baars, B.J. (2001). In the theater of consciousness. A workspace of the mind. Oxford University Press.

Blackmore, S.J. (2003). Consciousness: an introduction. Oxford University Press.

Chalmers, D.J. (1997). The conscious mind. In search of a fundamental theory. Oxford University Press.

Dennett, D.C. (1992). Consciousness explained. Back Bay Books.

Koch, C. (2004). The quest for consciousness. Roberts and Co.

Mc Ginn, C. (forthcoming). Consciousness and its objects. Oxford University Press.

Pinker, S. (1999). How the mind works. W.W. Norton & Company.

Vollenweider, F.X. & M.A. Geyer (2001). “A systems model of altered consciousness: Integrating natural and drug-induced psychoses.” Brain Res Bull 56: 495-507

A fundamental assumption in the field of neuro- psychology can be simply stated in the phrase “brain equals mind.” A fundamental question is: “How?” This insidiously simple inquiry is a truly difficult matter for those toiling at the workbench of consciousness research. In order to answer it, philosophers and neuroscientists must unite two languages, or rather, two perspectives: that of the first person and that of the third person. We are all familiar with examples of both. A reason- able first person account of a mental event could be something as mundane as “I see the color green.” The third person account of this event would be a long description of how a group of photons with collective wavelengths of 530 nanometers is processed by your eye and then your brain, a story usually reserved for psychology textbooks. Mapping this flow of visual information has been one of the great accomplishments of modern neuropsychology. Yet we can still only hypothesize how observable brain activity turns into the experience of vision. In other words, nowhere in the entire story of visual perception is there an adequate formulation of how this hunk of photons becomes the awareness of “green.” At the mo- ment, there is no way neuropsychology can answer the first person question, “How do I see green?” Asking this question in third person terms is like opening a Pandora’s box from which mountains of brain imaging data, a plethora of educated guesses, and several graphing calculators burst forth. Indeed, the brain imaging and stimulation techniques that are in the hands of today’s experimental researchers offer both blessings and curses. Noninvasive body imaging is a fortuitous invention for the third person pioneers. However, untangling numerous contradictory findings from a wide array of experimental tasks and participants is the bane of a cognitive neurosci- entist wanting to paint a coherent picture of the mind. With this dilemma in mind, what if we ask the first person questions: “Why does MDMA make me love everything?” Or, “How did taking that dose of LSD make the flowers sing?” There are certainly no fast and easy third person answers. Nevertheless, a growing contin- gency of researchers are concerned with cataloging and organizing the consistently reported subjective effects of drug-induced mind states and attempting to correlate them with measurements of brain activity. After all, the brain’s response to a drug can also be realized in the language of the receptors they influence, how strong their effects are at these sites, and how the subtle work of single neurons creates the pattern of activation observed in larger networks.


An obvious starting point in this task would be defining how an altered brain differs from a sober one. Accomplishing this work requires such technologies as functional magnetic resonance imaging (fMRI) to observe the metabolism of groups of brain cells in “real time,” as well as positron emission tomography (PET) hardware to detect the metabolism of specific radioactive substances introduced into the body by the experimenter. Pharmaco- logical developments have produced rapidly growing catalogues of psychoactive compounds that have meshed well with the application of biological imaging systems. A prolific amount of information is being gained from the dynamic interaction of drugs and imaging technologies. Fitting the data within a flexible framework that is compatible with preexisting theories on altered states of consciousness (ASC) is the work of many scientists. At this year’s conference in Tucson, Franz Vollenweider, PhD, of the University of Zurich and Thomas Ray, PhD, of the University of Oklahoma, offered both experimental results and theoretical ruminations about psychedelics and the nature of consciousness as it can be understood in physical terms. Vollenweider cites three qualities that characterize psychedelic experience and other altered states: Oceanic Boundlessness, Dread of Ego-Dissolution, and Visionary Restructuralisation. The first of these, Oceanic Boundless- ness, refers to the phenomena of unity, transcendence, and mystical encounter. The Dread of Ego-Dissolution is the experience of paranoia or milder forms of mental turbulence associated with the fear of loss of the ego and its boundaries. Finally, Visionary Restructuralisation refers to the sensory aberrations and distortions (a.k.a. visuals, hallucinations, etc.) that give hallucinogenic experiences their name. An altered state of consciousness questionnaire known as the APZ, developed by Adolph Dittrich in 1975, allows scientists to obtain self-reports of these independent and parallel aspects of the psychedelic experience. The APZ is one of several indices concerned with the subjective and physiological manifestations of ASCs, whether induced by drugs, other technologies like trance or meditation, or as a result of clinical psychosis.

Psychedelics as first person technology in the study of consciousness
by Dan Potthast and Tim Butcher

Vollenweider’s work is concerned with outlining the anatomical circuitry that may subserve these states of consciousness and the influence of pharmacological drug technologies on their functioning. Specifically, Vollenweider cites five feed- back loops between the thalamus, cortex, and subcortical limbic structures that control the “gating” of information flow to the prefrontal cortex. For instance, PET scan studies on the brains of subjects under the effects of psilocybin and ketamine reveal a higher level of activity in the frontal cortex than normal (hyperfrontality). Many drugs that influence dopamine or glutamate receptors will alter the way the thalamus filters incoming sensory stimuli, causing an “overload” of the prefrontal cortex accompanied by psychotic symptoms such as paranoia and loss of ego. Understanding the loss of self/non-self boundaries in neurological terms might allow insight into the way the self is constructed.

This concept might be best illustrated by somebody “having a bad trip.” The loss of one’s feeling of connection to external reality that often accompanies a difficult experience is precisely what Vollenweider predicts as one of the psychological effects of increased activity in the frontal regions of the brain, brought on by a kind of sensory overload. And perhaps not surprisingly, it is that very same activity that he proposes as also being related to feelings of transcendence, timelessness, and the hallucinatory effects of psychedelics (though he did not oversimplify this for editorial purposes as we are doing now). It seems here that the psychedelic journey through the subjectively “bad” feelings (of ego loss) might be exactly how we get the subjectively “good” feelings (of boundlessness), and vice versa. Thomas Ray, PhD, challenged the way most pharmacological literature classifies drugs. He explained that the most common type of outgoing transmitter involved in most psychedelic drug reactions is the chemical serotonin (5HT). Likewise, the most common sites in the brain on which psychedelics exert their effects are a subset of receptors classified as 5HT-2. In fact, most medical and psychopharmacology literature classifies various drugs according to the sites to which they bind or have the most effect upon.

It is this “one receptor” orthodoxy with which Ray takes strong exception. He argued that it is vastly oversim- plified to think of any drug in terms of only one receptor site on which it has some effect. A more sophisticated view would include not only the secondary and tertiary sites to which a drug binds, but also to the many different sets of receptors that undergo some alteration as a result of a drug’s binding to the “main” receptor (substituting the drug molecule for its endogenous analogue).


Relating first person questionnaires to third person brain measures permits us to map internal mind states to their neurological underpinnings. Ray proposed a way that this may be done. He argued that with as much as we now know about the brain and the drugs that affect it, we may gain a more complex idea of those effects by combining our knowledge of the various receptors in the brain with our knowledge of various subjective states known to be related to those receptors. Ray hopes that with this expanded vision of the brain and mind, we may eventually construct models of brain regions that relate to given behavioral functions, and how those affected functions relate to our internal states of consciousness.

Ray recommends the development of an abstract “receptor space,” which would have coordinate axes comprised of psychological scales such as those of the APZ running perpendicular to physiological dimensions, like the strength with which psychoactive substances bind to the receptors they influence. His project involves applying the work conducted by the National Institute of Mental Health Psychoactive Drug Screening Program (NIMH-PDSP) on chemicals such as psilocin, MDMA, MDA, 2C-B, DMT, mescaline, and others. The PDSP began in 1998 and was designed as a large scale survey of several classes of psychedelic compounds across a wide array of the receptors they influence. Within Ray’s dynamic systems framework, an average brain at a sober baseline could be understood in relation to brains under the influence of psychedelics or commonly-prescribed prescription medication, as well as minds with pathological disturbances. The potential therapeutic application of a model such as this is invaluable. In addition, it is representative of the expanding trend of researchers uniting first and third person perspectives through growing technologies. Ray noted an analogous relationship between the 18 month doubling of the computing capacity of microprocessors and a 50 year doubling of the psychoactive substances being synthesized. The current pharmacological explosion coupled with new ways to stimulate and view intact brains offers consciousness researchers a massive library of tools to help bridge the explana- tory gap between subjective phenomena and objective brain measures.


In addition to work on psychedelics and visual awareness, Olivia Carter, a PhD student at the University of Queensland in Australia, presented several studies dealing with attention and short-term memory in subjects who were given psilocybin. Subjects in these experiments exhibited behavioral effects also seen in patients diagnosed with schizophrenia. Specifically, people given psilocybin had the subjective feeling that they were performing quite well on memory-attention tasks, when in fact their performance was well below that of normal subjects. In fact, even though one experiment presented the subjects with an audible “beep” sound when they made a mistake at the task, one subject insisted that the computerized beep was wrong and that he was in fact perform- ing flawlessly. Perhaps some readers have seen this very same effect in a friend or colleague under the effects of a psychedelic drug. We hate to break the bad news here, but when looking for verifiable increases in memory and attention under a psychedelic, the only factor that is really increased is the subject’s illusion that he/she is performing flawlessly!


While psychedelic research is often marginalized in scientific communities, in Tucson, discussion of psychedelics was integrated throughout the conference. In addition to the plenary panelists, several others presented on topics related to psychedelics, including ketamine expert Karl Jansen, MD, PhD, and anthropolo- gist Michael Winkelman, PhD. Ayahuasca was a popular topic, with a number of lectures on the effects and anthropology of its use. Researchers at the Tucson conference were actively studying the mechanism of psychedelic drugs with the tools of consciousness research, and using these drugs themselves as tools of consciousness research.

The biennial “Toward a Science of Consciousness” conferences are a rich and fertile backdrop for the discussion of the connection between mind and brain, and the infinitely complex implications of these connections. It is the view of the authors that these questions should not be left merely up to the above specialists, but will also benefit from the input of those with experience in the various aspects of consciousness that are only illuminated by the psychedelic experience.