Any hypothesis of the nature of consciousness has to address several facts – at least these facts, as a minimum, and there probably are other constraints as well as these.
- There is an intimate connection between memory and consciousness. We remember what we have been conscious of. We know we have been unconscious if there is a discontinuity in our memory of events. Memories ‘package’ experience in a form that closely resembles the conscious experience of events. We feel a flow of future projections to present conscious experience to past memories without any sharp change in the type of awareness.
- Consciousness and dreaming have some commonalities but are quite different in their connection to perception and action. Dreams are not about reality and usually not result in action and usually are not remembered.
- There is a time delay in the formation of a conscious experience which we do not perceive. It is as if we were automatons who, for no good reason, experience a continuous movie of our immediately past perceptions and actions. We feel our consciousness is a real time event when it is not. The best summary of the experimental evidence for the time delay that I have found so far is Roger Penrose’s review of the evidence.
- Consciousness is not a completely faithful model of what is actually happening. Illusions and misinterpretations are frequent and somewhat predictable. We do not even have a completely accurate model of our own minds. For instance: there are blind sight and other knowing-without-awareness-of-knowing; there are phantom limbs and other awareness-of-the-nonexistent.
- The way that conscious experience presents itself seems arbitrary and personal. Why is a particular wavelength of light seen as a particular colour? Is my red your red? Qualia (properties of perceptions) are an aspect of consciousness.
- Consciousness happens at the same time as some pronounced activities in the brain, particularly reciprocal communication between the cortex and the thalamus, low amplitude but high frequency brain waves, activity in the reticular formation. There is a summary in Scholarpedia but it is fairly technical.
- Our consciousness can be affected by various mental illnesses, drugs, stressful situations etc. We can also learn to modify our consciousness (with meditation for example).
We need a picture of consciousness that fits with and helps explain these facts.