The Nature of Conscious Experience


Aspects of The Theory 

Tawny Fish Owl

This page provides a brief informal introduction to the theory known historically as Single Cell Consciousness (Edwards) or the Single Neuron Theory of Consciousness (Sevush) but maybe best described as Experience as a Property of Individual Cells. Other documents in this section are very brief accounts of related issues. My most recent formal account of the theory is given under Online Essays as Reality, Meaning and Knowledge. Previous published accounts are available under Publications.

Perhaps the most baffling unanswered question in science is why we have the particular sorts of conscious experiences we seem to have, given what we know about our brains. (I doubt we should expect an answer to 'Why is there experience at all?'.) There are several reasons for this question being difficult, but the most important may be that we are looking for the wrong sort of answer. Almost everyone assumes that we are trying to explain one instance of experience/awareness in each person's brain, one event, one observer, one subject; one consciousness. However, as William James pointed out, having one instance of awareness in a brain makes very little sense, whether in terms of logic, physics or neurology. It would make much more sense if there were lots of instances and lots of subjects, even if it seems strange. Perhaps the most basic biological reason for there being many subjects in a brain is that a brain is not a single living unit but a colony of cellular units that are not joined together by any mysterious 'life force'. 

The hypothesis arose from the simple strategy of trying to find an explanation for awareness that fits with what we know about the physics of the brain. There appears to be only one option that works; that each brain cell is aware separately. The immediate reaction to this is often that it would cause chaos. However, if all cells get a congruent input there is no reason why it should. We no longer think of a central 'agent' in a brain; behaviour is determined by networks. The same argument can be applied to awareness.

The philosopher Daniel Dennett might be said to have come to a similar conclusion, in proposing that our awareness comes in the form of 'multiple drafts' throughout the brain. However, Dennett provides no specific physical basis for his suggestion and so does not really address the key problems. Single Cell Consciousness deals with these problems head on, by specifying that each copy of awareness belongs to an individual cell and is as complete as we experience, rather than being a partial 'draft'. There can be no 'combined' or 'global' awareness over and above the awareness of each cell. Not only would this require some strange metaphysical 'glue' but it would be in direct contradiction to what we know about how the brain works.

Many people's reaction to this suggestion is that it cannot possibly be true. However, I would respectfully suggest that this simply indicates how deeply rooted false assumptions can be. (They may be rooted in a Darwinian mechanism that preserves a sense of a single identity.) The key point is that, whatever difficulties there might be with this idea, they might be soluble, whereas the difficulties with the idea of a single awareness in a brain are not only worse, they are insurmountable.

Taking the idea of an observer seriously

Physics, and particularly modern physics, relates everything to an observer. An observer is something that receives information about other parts of the universe from a particular frame of reference, which includes position, time and movement. An observer is something with a single relationship to other parts of the universe. It cannot be a collection of things, each with a different relationship to the universe and, therefore, receiving different information about the universe. Physicists assume that a human being can provide a single thing with a single relationship to the universe, but it quite obviously cannot, since a human being is a collection of things. Importantly, for each of these things, their relationship to the universe includes relationships to the other things. Even the brain is such a collection, and quite specifically a collection of nerve cells, each receiving a separate input of information from a different frame of reference. The very fact that brain cells are related by message sending and receiving means that they cannot all be one observer receiving the same message.

It might seem that one could consider the brain as a whole, with a single set of inputs from all the nerves coming from eyes, ears, fingers and elsewhere. But we know that is not what a brain is. Most of it is made up of the connections that allow these inputs to be brought in, tidied up, collated and compared with past experience and interpreted in terms of ideas like ‘thing’ or ‘colour’ before they are received by an aware observer. We cannot say that the information coming in to the right side of the brain and the information reaching the left side of the brain are reaching a single observer, because there is nothing that gets both inputs. Not only can nothing act as observer for both sets of inputs, nothing can respond to the combination of the two inputs because they are arriving at different places, one of which has no information about what is arriving at the other.

The idea of a brain being one aware observer is simply logically incoherent. It is neurologically meaningless. It is incompatible with physics. 

What neurology tells us

What neuroscience has established is that each brain cell functions as a separate receiving unit. There are a variety of routes for passing information from cell to cell, including direct channels between cell interiors in some cases. However, there is no evidence of sharing of complex patterns of incoming information, and it is complex patterns of incoming information that we need for the sort of observing that we seem to experience. If cell A has a pattern of 10,000 inputs through its synapses in 10 milliseconds, that pattern is not available to cell B, and vice versa, even if cell A and cell B have links between their cell bodies. Cells could be observers, but brains cannot be.

If there are many observers in a brain it might seem that there should be conflicting experiences, and behaviour should be reduced to chaos. However, this is not what neurology predicts. The information coming in to every cell would be consistent, since it arises from the same sensory input. Inasmuch as two brain cells dealt with the same sort of information they would get copies of the same input. There is no doubt that information coming in from the senses is sent out in many copies to many cells. A cell in the occipital cortex, which fires when inputs from the retina indicate that an edge of an object has moved, will send that information to perhaps ten thousand cells. The idea that there might be thousands of cells all receiving the same information is entirely consistent with what we know about brains. Again, the idea of a single observer with a single copy of an input is absurd, because everything in the brain is sent around in lots of copies.

What seems to have happened in the development of a received dogma about the link between awareness and messages between brain cells is that these thousands of copies of a piece of information are seen as somehow 'in bulk' generating awareness. But this does not make sense because in order for the information to mean anything it has to arrive at a receiving unit, our observer, along with whatever other information it is to be experienced with (brown and cow, red and lorry) so that it can be made use of. Presumably only one copy of any piece of information will arrive at any receiving unit (a cell). Other copies would have no further meaning to the observer in hand. All they can do is provide a meaning to other observers.

The argument that experience has to be a property of individual cells has actually been around for at least 300 years. It may have been overlooked partly because it is so counterintuitive but also because it has been hard to address empirically. That situation may now be about to change.

A new prediction

One of the advantages of the Single Cell Consciousness idea is that, in resolving one problem, it raises a new problem that ought to have a solution open to testing by experiment.

As William James pointed out, the arguments that make the idea of a brain as a single observer absurd also cast doubt on the possibility of a cell being an observer. A cell is a single receiving unit in neuroanatomical terms, but in fundamental physical terms it might seem not to be. It could be argued that a cell is a branching tree of separate receiving units, each of which receives the information coming in to a tiny piece of cell membrane but nothing else. You might even say that each atom of the cell receives its own information and there is no possibility of an observer being more than one thing; one atom. The trouble is that down at the atom level there is no pattern of signals that could encode an experience. We are fairly sure that experiences are encoded in electrical potentials. The richness of our experiences is debated but probably requires an input with somewhere between 100 and 10,000 degrees of freedom. This is about right for the whole dendritic tree of a cell, but not for anything much smaller. 

James's point poses a serious problem if you stick with 1890 physics. However, modern physics may offer a way out. In modern physics the elements of the universe are not tiny lumps but rather distributed dynamic patterns (sometimes described as wavelike, but that can bring its own misconceptions) characterised by dispositional properties such as spin, mass, and charge. Although some of these dynamic patterns are confined within atoms, some, including more loosely associated electrons, cover much larger domains. Some are specifically associated with large ordered structures. Thus crystalline structures are 'inhabited' by energy-bearing modes whose units are known as phonons and which can exchange energy with the photons of electrical fields through piezoelectric or other electromechanical coupling. Large scale modes of this sort behave as wholes with no parts, so any information received at any point in a domain defined by such a mode might be seen as being received by a single 'thing'.

Almost by definition, cell membranes, as liquid crystals, should be inhabited by phononic modes. In fact piezoelectric oscillations are recognised in specialised nerve cells in the inner ear known as outer hair cells. To be of any relevance to awareness in cells within the brain such modes would probably have to be higher frequency and lower amplitude, but it would not be unreasonable to predict that such modes might exist. For the hypothesis to be testable these modes would need to be involved in energy transfer in the integration of electrical potentials in cell dendrites. We know that electromechanical coupling occurs in dendrites but not whether it has any role in resultant firing. If it does it may be possible to test this with drugs that alter coupling mechanisms.

Thus the suggestion is made that the observers in our heads are phononic modes and that these might be discoverable. The detail of the theory may well be wrong, but at least it is consistent with a local biophysical mechanism, which the idea of a global awareness does not seem to be.


Neurobiology tells us that our brains are colonies of separate receiving units: brain cells. An observer is a receiving unit. A receiving unit cannot have direct evidence of anything received by another receiving unit. Just as none of us has direct evidence of consciousness in other brains, no cell will ever have direct evidence of awareness in other cells. So the fact that we do not feel ourselves to be multiple observers should not be a surprise. The existence of other observers has to be inferred from logical argument of the sort given here. The cell appears to be the only level of structure that could have what we call a human experience. It may be possible to identify the fundamental dynamic units involved.