Imagine losing your sight. Now your hearing. Your sense of touch fades until you can’t feel the ground beneath your feet or the clothes on your skin. Taste and smell vanish. Physical pain disappears entirely. Even your emotions flatten out until joy and sadness are just words for things you used to feel.
But you can still think. You remember. You reason. You make decisions.
What would that be like? Would you still be conscious? Would there still be a “you” experiencing… what exactly?
This isn’t some pointless philosophical exercise. Every one of these losses has a name, a medical diagnosis, real people living with it right now. Blindness and deafness, obviously. But also anosmia (no smell) and ageusia (no taste), which thousands discovered they had during COVID. Congenital insensitivity to pain, where people literally cannot feel physical pain from birth. Peripheral neuropathy that kills sensation in the limbs. Neurological disorders that can shut down sensory processing even when the hardware still works. And anhedonia, where the ability to feel pleasure just stops.
Some people have two or three of these conditions at once. A few have even more. Nobody has all of them, as far as I know. But taken together, they sketch the outline of something I’ve been thinking about: a person whose sensory and emotional world has been stripped down to almost nothing, but who keeps thinking, remembering, planning.
I’ve been working on this thought experiment I call Omnisensory Nullia. Terrible name, maybe, but it does what I need. “Omnisensory” points to all the senses. “Nullia” points to absence. Put together, it describes a mind at the very edge of experience, where almost all the usual inputs have gone quiet, yet the lights are not completely out.
What happens when the “movie” is gone but the projector is still running.
In this imagined state, there is no color, no sound, no taste, no smell, almost no bodily feeling, and very little emotional color. But there is still a stream of thought. You can still notice that one idea followed another. You can remember that yesterday you were worried about something and today you are less so. You can still plan, regret, hope in a thin, abstract way.
What kind of consciousness is that?
Most of us, most of the time, treat consciousness as basically the movie of our senses with emotions layered on top. The way coffee smells. The feel of hot water on skin. The tension in the chest when you get bad news. The relief when it passes. We build our theories of mind around that thick, textured picture.
Omnisensory Nullia flips the direction of the question. Instead of starting with rich experience and asking how the brain produces it, it starts at the other end and asks: how much can we take away and still have a conscious subject at all. What happens when the “movie” is gone but the projector is still running.
There are a few possibilities.
Maybe nothing is left. Maybe once you remove sensation and emotion, what remains is just blind information processing, no different in principle from a very complicated spreadsheet. On that view, a person in an Omnisensory Nullia state would no longer be conscious, no matter how clever their thinking looks from the outside.
Or maybe there is a very thin kind of experience left over. Not images or sounds, but a bare sense of time passing, of thoughts arriving and departing, of “mine” versus “not mine.” A sense that something is happening, even if it has almost no flavor. If that is possible, then consciousness might be less about sights and feelings than we usually think, and more about the way a mind tracks itself through time.
I’m not sure where I land yet. The more I push on this edge case, the less confident I am about the line between rich experience, thin experience, and no experience at all. What I am sure of is that our everyday sense of “being conscious” hides a lot of structure. We bundle together sight, sound, body, mood, memory, and thought as if they were a single package. Omnisensory Nullia pulls that bundle apart and asks: if you had to give pieces of it up, one by one, at what point would you say that the lights have finally gone out?