Global Workspace Theory is among the most influential scientific theories of consciousness. Its central claim: 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.
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.]
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[1] Ned Block's well-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?
7 comments:
But we do know a fair bit about distractor inhibition in attention, which can be at multiple neurological levels. So, asking someone to attend to their feet will immediately and "invisibly" block all that inhibition.
I'm inclined to agree that consciousness is graded rather than on/off. On an introspective level, something can be fully conscious (I am aware of it) or marginally conscious (once you mention it, I realize I'd been aware of it for some time). Moreover, those two labels (fully vs marginally) are shorthand for places along a continuous gradient.
Here's an experience that I think avoids the refrigerator light error: once in a rare while, in conversation, I initially fail to understand something and say "I missed that, could you say it again?"), but then the understanding catches up to me - AFTER I've had time to ask for clarification but BEFORE the speaker can clarify. I.e., I didn't understand the words immediately, but did after another moment of auditory processing. This seems like a perfect case of a "borderline conscious" experience (the experience is not determinately attention-locked) with no room for "refrigerator light" error (there's no introspective attentional shift) and unlikely to be an introspection error (it's based on my actions, not just thoughts).
On a theoretical level, I believe pretty much everything in biology is fuzzy-edged and graded. Strict categories are tools we apply to help us understand the world, not a natural feature of the (biological) world... so I would consider "no borderline cases" the claim that requires evidence!
...Yet, as much as I hate Global Workspace Theory, I don't see why it's inconsistent with borderline-conscious experiences. Analogizing the global workspace to a little central spotlight, my misunderstood words drifted gradually into the light. I have some thoughts about neural mechanisms which I'll post separately (or maybe I should read your draft book on consciousness to chime in better??)
Neural mechanisms follow-up comment!
I've heard some arguments lately that top-down, whole-brain-affecting mental operations (e.g. attention, executive control) are implemented via analog spatial computing produced by interactions among brain-wide electrical field oscillations. (These cause and are caused by neural activity, but these fields aren't transmitting via neurons and synapses.) If this is true, and applies to consciousness (subjective experience), then conscious experiences are the ones that get communicated across the brain via these interacting electrical fields.
This seems largely consistent with Global Workspace (it's explicitly a global broadcast) but it's capable of being graded. In fact there's evidence for a grading mechanism! A local event's impact on the field depends in part on how well that event synchronizes with the field's oscillations - a continuous, analog sine wave.
I don't see anything that distinguishes predictions of Fame vs GWT, though I think these fields act more like a workspace than like fame - local neural events read and write to them.
Thanks for the comments!
Benjamin: I think it's plausible such after-the-fact cases are borderline cautious. One standard example of such a case is when you start attending a clock tower chiming after about the fourth chime and you can count back the unattended chimes in your memory. Now it could be that those first chimes were borderline conscious -- but they could also have been nonconscious and only brought into conscious now, but conscious but peripheral. I think it's hard to know introspectively which is the case.
On GWT allowing borderline cases: Yes, maybe through the mechanisms you describe. Dehaene's version GNWT is probably the best known, and Dehaene is explicit that a process either wholly "ignites" into the workspace or does not, with no or few intermediate cases. GWT theorists in general tend not to talk as thought borderline cases are common, but that could certainly change with the right model.
Referencing chimes example...reminding me of echo quality from my Navy days...
Gemini You and Me...Conclusion: The third-person evidence suggests the path to consciousness is different:
Auditory: The brain uses the MMN to automatically screen the input. Only truly important, pattern-breaking sounds are passed forward to the GWT network for "Fame."
Visual: The brain relies more on attentional selection in the visual pathways themselves to determine which information gets enough Recurrent Processing to achieve "Fame."
In this sense, listening allows the conscious system to "rest" more because the automatic, non-conscious processing in the auditory stream is so efficient at separating signal from noise.
Would you be interested in how the competing theory—the Early Correlates of Consciousness (ECC)—challenges the late P3b/GWT view, especially concerning visual processing?
The Dimensional Shift Perspective in metaphysical discussions, is the shift from a First-Person/Ego-centric view to a Third-Person introspective view, described as naturally moving from lower dimensions of consciousness to a higher ones or beyond...like sense of feet in a sock feeling feet on the ground...
The reason I find my "say it again?" example more convincing than the clock tower, is that in SIA I was demonstrably conscious of the sounds from the beginning - only at low fidelity.
That said, I can construct explanations for the SIA phenomenon that include marginal consciousness or lack marginal consciousness...
With: The words-experience was gradually entering consciousness.
Without: Word-sounds and word-understanding are separate things, each of which became immediately fully conscious as soon as the appropriate brain mechanisms finished processing them.
Honestly the part that convinces me the most is simply "everything in biology is fuzzy-edged and graded." I would be shocked if any aspect of the brain had hard-edged on-off states. It's true at higher levels: the neural mechanism I detailed (and others I've seen about whole-brain state-switching) relies on continuous, analog processes. And at lower levels: within a neuron, the relationship between input & output is stochastic, not logical.
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