2. The Global Workspace

The best theory of phenomenal consciousness is one that equates it with the contents of the so-called global workspace (a.k.a. working memory)—or rather, with a subset thereof. Why a subset? Because although conceptual information can be bound into the contents of perceptual and imagistic states, and made available in the global workspace, my view is that concepts don’t make a constitutive contribution to the phenomenal properties of the resulting states, but at best a causal one. Phenomenal consciousness is restricted to globally broadcast nonconceptual—fine-grained—information.

Put differently, phenomenal consciousness is access-conscious nonconceptual content. Phenomenally conscious states are those that are available for verbal report (and puzzlement), for planning, to serve as a basis for inferences, and to give rise to long-term memories. Note that there is a nice confluence here between the empirical evidence collected by cognitive neuroscientists and the first-personal nature of phenomenal consciousness as introduced by philosophers. For states that enter the global workspace will thereby be available to be reported on and puzzled over from the first-person perspective. This is because those states will be available to the systems (broadly speaking, executive-function systems) that are engaged when one reflects, introspects, and becomes puzzled.

The evidence for global-workspace theory comes from many sources. But some of the most elegant derives from studies using fMRI, EEG, or direct neural recording (or some combination thereof), in conditions where perceptual input is kept constant across conscious and unconscious conditions. Some experiments use very brief and faint stimuli, which are either backward-masked by a follow-up stimulus or have to compete for attention with a later stimulus (as in the so-called attentional blink). In both of these sorts of case, the stimulus parameters (intensity and duration) can be kept fixed, but people are only aware of the stimulus on about 50% of trials. One can then see the difference that conscious perception of the exact same stimulus makes in the brain. (Answer: global as opposed to local activity.) Other experiments use full-strength but bi-stable stimuli, as in binocular rivalry, where completely different images can be presented to the two eyes. One can take direct or indirect measures of the moment when the seen-image switches from one stimulus to the other, and see what happens in the brain concerning the very-same content in seen versus unseen conditions. (Same answer.)

Importantly, we now know that the activity in prefrontal / executive systems that is unique to consciously-experienced trials doesn’t result from response preparation, because the same findings emerge even when the responses are held constant as well (in conditions where people have to guess at a line-orientation whether they see it or not, in blindsight-like conditions), and also in completely passive viewing conditions where no response or any sort is required or made.

Of course, global workspace theory isn’t the only game in town. But frankly, most of the alternatives have little to be said for them. Perhaps the most plausible competitor is Ned Block’s fragile-short-term-memory account, which is supported by the alleged richness of conscious experience in comparison to what can enter working memory and be retained for verbal report. But in fact these data can readily be explained in terms of conscious perception of the gist of a scene, which is known to be processed swiftly and reliably independent of focal attention. So the gist is conscious, and some individual items are conscious, and the remainder can become conscious when specific currently-unconscious fragile-short-term-memory contents are targeted with attention following a retrospective cue. Strictly speaking, the evidence reviewed here is only evidence of the cognitive / neural correlates of phenomenal consciousness, not of what the latter itself is. But for anyone who has principled reasons for rejecting non-physical qualia, the stronger inference is warranted by default. In fact, however, we can do better. Global-workspace theorists can explain why the consciousness issue should get such a grip on us in the first place. I will say a little about that tomorrow.

11 Comments

  1. Peter, your book spurred me to take another look at global workspace theory, and to turn a critical eye on higher order theory, for which I’m grateful!

    I sometimes think a better name for global workspace theory might be broadcast competition theory. Too many people seem to see it as being about a central storage location rather than the all or nothing competition by processes to broadcast their content to all the other processes, to briefly achieve “fame in the brain.”

    On conceptual vs non-conceptual content, it seems to me that it’s like something to realize a conceptual idea, and that that realization usually comes with, perhaps fleeting, sensory imagery of some type. Or do you mean something different by conceptual content?

    • Peter Carruthers

      SelfAwarePatterns, yes, entry into the global workspace results from competitive processes. And you are right that the result is all or nothing. There is a nice convergence here between the neuroscientific findings, which suggest that entry into the GW is a sharp step-function, and our introspective grip on phenomenal consciousness, which is likewise all or nothing. (Even the very faintest of experiences is definitely, determinately, like something to undergo.) As a result, though, one shouldn’t use Dennett’s image of “fame in the brain”, because fame is always graded. Someone can become just a little bit more famous, but a mental state can’t become a little bit more phenomenally conscious.
      As for conceptual content, I agree that it can be access conscious, while always being accompanied, as you say, by some or other form of sensory imagery. For instance, when you hear someone say, “You are welcome in my home”, the conceptual content (the meaning) is bound into the auditory event file along with details of timbre and accent and loudness. And the result is a phenomenally conscious experience, of course. But my own view is that the conceptual content of the episode never makes a constitutive contribution to the phenomenal properties of the experience, but at most a causal one. The argument for that conclusion is somewhat orthogonal to the main thesis of the book, but is spelled out in work jointly done with Bénédicte Veillet. See our paper “Consciousness operationalized, a debate realigned.” Consciousness and Cognition, 55 (2017), 79-90. (Available on my website if you are interested.)

      • Good point on Dennett’s analogy. His multiple drafts seems like GWT minus the conscious “avalanche” or “ignition”, leaving the “winner” to be decided by the reporting systems. It does seem like Dehaene’s empirical work establishes that the winner actually happens pre-report, and Dennett himself in recent interviews seems to acknowledge this.

        Thanks for pointing out that paper! I’ll check it out, and probably some others on your site.

      • So if someone says “you are welcome in my home” and then they say “wahgahyah eh yoh koso”, the phenomenal experience of each will be similar, just a different set of sounds? I can’t help but think that immediate comprehension of the words registers as phenomenal. Is there evidence one way or the other?

      • jeffrey g kessen

        “Even the very faintest of experience is definitely, determinately, like something to undergo.” Hmm, you’ve a very robust faculty of self-apprehension. The neuroscience of vegetative states, however, suggests something rather different. Also, isn’t there something circular in defining a state of subjective experience as something that it’s like—to experience?

  2. Hi Peter.
    can you clarify a few of your claims please?
    1. Is phenomenal consciousness a subset of access consciousness?
    2. Is being targeted by attention what makes something access conscious?
    3. what’s a concept (in this context)?

    Also, how do you distinguish between Prinz’s view and your own?

    • Peter Carruthers

      Tom, happy to do so.
      1. Yes. Both nonconceptual and conceptual content can be access-conscious, but only the former makes a constitutive contribution to phenomenal consciousness (a.k.a. gives rise to “hard problem” type thought experiments).
      2. Attention is necessary but no sufficient for access consciousness. No global broadcast without attention, but a representation can be too faint/fragile to be boosted over the threshold for global broadcasting by attention.
      3. In this context, concepts don’t need to he subject to the so-called “Generality Constraint”. (So you can call them concept-like if you like.) But they are “chunky” representations of a category which can serve as a node for collecting information about instances of the category. Nonconceptual representations, in contrast, are fine-grained.
      Also: that’s a hard question, which I confess I haven’t thought a lot about (or not recently enough to bring the differences easily to mind). But obvious differences are: he doesn’t address the “explanatory gap” directly, and gets the distribution of phenomenal consciousness wrong.

    • That may not be a fair request since I guess you have tried. So it may be my own fault that I’m still not quite getting the concept of concepts. Does the “chunking” of information into concepts have to do with how we manage our conscious thinking (and speaking) about things as opposed to the unthinking aspects of consciousness?

  3. Peter, wordings like “conscious states available for verbal report” or “reflection and introspection” look as implying a conscious-self needed for the verbal report and for the reflection/introspection. So the question about introducing self-consciousness comes up again. Don’t you think so?.
    Also, regarding your reply in “1. Consciousness problems”, can we really consider self-consciousness (the capacity to think about one’s own mental states) as metacognition (awareness of what one knows)? And should we take as not problematic the needed postulate of a pre-reflective self-consciousness ?

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