Global Workspace Theory is among the most influential scientific theories of consciousness. Its central claim is: You consciously experience something if and only if it’s being broadly broadcast in a "global workspace" so that many parts of your mind can access it at once — speech, deliberate action, explicit reasoning, memory formation, and so on. Because the workspace has very limited capacity, only a few things can occupy it at any one moment.

Therefore, if Global Workspace Theory is correct, conscious experience should be sparse. Almost everything happening in your sensory systems right now — the feeling of your shirt on your back, the hum of traffic in the distance, the aftertaste of coffee, the posture of your knees — should be processed entirely nonconsciously unless it is currently the topic of attention.

This is a strong, testable prediction of the theory. And it seems like the test should be extremely easy! Just do a little introspection. Is your experience (a.) narrow and attention-bound or (b.) an abundant welter far outrunning attention? If (b) is correct, Global Workspace Theory is refuted from the comfort of our armchairs.[1]

The experiential gap between the two possibilities is huge. Shouldn’t the difference be as obvious as peering through a keyhole versus standing in an open field?

Most people, I’ve found, do find the answer obvious. The problem is: They find it obvious in different directions. Some find it obvious that experience is a welter. Others find it obvious that experience contains only a few items at a time. We could assume that everyone is right about their own experience and wrong only if they generalize to others. Maybe Global Workspace Theory is the architecture of consciousness for some of us, but not for everyone? That would be pretty wild! There are no obvious behavioral or physiological differences between the welter-people and the workspace-only people.

More plausibly, someone is making an introspective mistake. Proponents of either view can devise an error theory to explain the other.

Welter theorists can suggest memory error: It might seem as though only a few things occupy your experience at once because that’s all you remember. The unattended stuff is immediately forgotten. But that doesn’t imply it was never experienced.

Workspace theorists, conversely, can appeal to the "refrigerator light error": A child might think the refrigerator light is always on because it’s always on when they check to see if it’s on. Similarly, you might think you have constant tactile experience of your feet in your shoes because the act of checking generates the very experience you take yourself to be finding.

In 2007, I tested this systematically. I gave people beepers and collected reports on whether they were having unattended tactile experience in their left feet and unattended visual experience in their far right visual periphery in the last undisturbed moment before a random beep. The results were a noisy mess. Participants began with very different presuppositions, came to very different conclusions (often defying their initial presuppositions), plausibly committed both memory errors and refrigerator-light errors, and plausibly also made other mistakes such as timing mistakes, missing subtle experiences, and being too influenced by expectation and theory. I abandoned the experiment in defeat.

But matters are even worse than I thought back in 2007. I’m increasingly convinced that the presence or absence of consciousness is not an on/off matter. There can be borderline cases in which experience is neither determinately present nor determinately absent. Although such borderline cases are hard to positively imagine, that might just be a problem with our standards of imagination. The feeling of your feet in your shoes, then, might be only borderline conscious, neither determinately part of your experience nor wholly nonconscious, but somehow in between — contra both the welter view and the workspace view.

So there are three possibilities, not two. And if introspection struggles to distinguish the original pair, it fares even worse with a third. Arguably, we don’t even have a coherent idea of what borderline consciousness is like. After all, there is nothing determinate it’s like. Otherwise, it wouldn’t be borderline. As soon as we attempt to introspect borderline consciousness, either it inflates into full consciousness or it vanishes.

Consciousness Essential Reads

If consciousness includes many borderline cases, that’s probably also bad news for Global Workspace Theory, which generally treats experiences as either determinately in the workspace or determinately out of it. However, closely related broadcast theories, like Dennett’s fame-in-the-brain theory, might better accommodate borderline cases. (One can be borderline famous.)

There’s a profound experiential difference between a world in which we have a teeming plethora of peripheral experiences in many modalities simultaneously and a world in which experience is limited to only a few things in attention at any one time. This difference is in principle introspectible. And if introspective inquiry vindicates the welter view, or even the borderline view, one of the leading scientific theories of consciousness, Global Workspace Theory, must be false. The decisive evidence is right here, all the time, in each of our ongoing streams of experience! Unfortunately, we turn out to be disappointingly incompetent at introspection.

[Thanks to Bertille de Vlieger for a delightful interview yesterday morning which triggered these thoughts. Look for a written version of the interview eventually in the French philosophy journal Implications Philosophiques.]

[1] Ned Block’swell-known discussion of the Sperling display is similar in approach. We can’t attend simultaneously to all twelve letters in a 3 x 4 grid, but it does seem introspectively plausible that we visually experience all twelve letters. Therefore, experience overflows attention. (I’m simplifying Block’s argument, but I hope this is fair enough.) The problem with Block’s version of the argument is that it’s plausible that we can attend, in a diffuse way, to the entire display. Attention arguably comes in degrees, and the fact that you’re looking at a 3 x 4 display of letters might be represented in your workspace. To move entirely outside of attention, it’s safest to shift modalities and choose something far removed from any task — for example the pressure of your shoes against your feet when that is the farthest thing from your mind. Is that part of your experience?