Here's my first blog post. I recently read Quilty-Dunn’s article “Is Iconic Memory Iconic?” Quilty-Dunn recently received the William James prize, from ASSC, for this excellent piece. The end of the article, in particular, contains an argument that I find interesting, so I wanted to take some time to discuss it here.
Representations in iconic memory have an iconic (image-like) format. Representations in visual working memory have a discursive (language-like) format. Quilty-Dunn shows this convincingly, in my opinion. If you disagree, please take this for granted in what follows anyway.
Now, some mental phenomena are cognitive. Others are perceptual. What’s the difference between the two? Well, some have suggested that it’s a difference in representational formats. Visual perception, for instance, depends on representations that have an iconic format. Cognition depends on symbolic, language-like representations. If you hold that the difference between perception and cognition is a difference in representational format, then only iconic memory representations are truly perceptual (in the visual domain). Representations stored in working memory, on the other hand, are not perceptual representations.
In the consciousness literature, some – notably, global workspace theorists – hold that the contents of conscious experiences correspond to working memory (or global workspace) representations. Given that working memory representations aren’t perceptual, it means that, if global workspace theory is true, properly perceptual contents are never conscious. Perceptual contents are never conscious... What?! How did we get there? That doesn’t seem right.
What should we do? Quilty-Dunn suggests several possibilities.
The obvious option is to reject the view that conscious contents are the representational contents stored in working memory. Proponents of local theories of consciousness, like Victor Lamme or Ned Block, for instance, would probably go this way.
The second option is to accept higher-order theories. According to at least some versions of higher-order theory, the content of your visual experience (what you visually experience) depends on iconic representations, but those representations don’t become conscious on their own. Instead, you become conscious of their content through higher-order mechanisms (whatever they are). So, no problem here.
I'm not a big fan of the first option. I like the second option (an advantage of the higher-order theory is that it gives you some flexibility on this issue). But if you’re a global workspace theorist – and after all, why not, it’s a good theory – you don’t want that. And, obviously, you don’t want to go with the first option either.
So, this article makes quite clear that you can’t hold both that the difference between cognition and perception is a difference in representational format, and that our (perceptual) experiences depend only on the contents of working memory – or global workspace.
The third option is to reject the view according to which the difference between cognition and perception is a difference in representational format. Instead, you should turn to more “architectural” accounts of the border between perception and cognition, and hold that perception can involve both iconic as well as language-like representations.
As it happens, Quilty-Dunn wrote another paper defending precisely that view. His view is that perception involves "object files" that can incorporate index-like representations of individual objects, as well as abstract, amodal features. If visual perception depends on those object files, then visual perception can’t be defined as involving only iconic representations.
At first, I wasn’t convinced by this view. After all, those object files don’t seem genuinely perceptual. Indeed, object files are used as inputs in inferences, and they don’t reduce to “perceptual or sensor-motor primitives”, as Susan Carey would have it. If so, a simple way to answer Quilty-Dunn’s argument is just to deny that object files are genuinely perceptual. And if object files are not perceptual in nature, why are they relevant to the debate, and why should we care?
Of course, Quilty-Dunn addresses this worry. I'm still not entirely sure where I stand on this, but here's one point I found convincing: it does seem like object files are crucially involved in perceptual phenomena, like transsaccadic memory. The fact that the same objects can be re-identified easily across saccades despite changes in the input is because of this memory. And you wouldn’t hold that transsaccadic memory is not a perceptual phenomenon, would you? Then… there you have it, it seems like you have to hold that object files can be properly perceptual, since they are at the center of crucial perceptual functions. If so, you can’t define the difference between perception and cognition as a difference in representational format, since object files aren’t (purely) iconic representations.
To sum up, if you like the global workspace theory, or if you think that conscious contents are the contents stored in working memory, you’re committed to an “architectural” view of the difference between perception and cognition. But that’s all good, Quilty-Dunn says, because you can accept a kind of “perceptual pluralism”, according to which working memory representations can be considered genuinely perceptual, even if they don’t have an iconic format.
Unfortunately, those "architectural accounts" are under-developed at the moment. When you reject the "representational format" account of the difference between perception and cognition, you know what you lose, but it's unclear what you get. So, I guess we'll have to wait for additional research in this domain.
I thank Jake Quilty-Dunn for reading this before I posted it. Again, congratulations to him for the William James prize!
MM
Representations in iconic memory have an iconic (image-like) format. Representations in visual working memory have a discursive (language-like) format. Quilty-Dunn shows this convincingly, in my opinion. If you disagree, please take this for granted in what follows anyway.
Now, some mental phenomena are cognitive. Others are perceptual. What’s the difference between the two? Well, some have suggested that it’s a difference in representational formats. Visual perception, for instance, depends on representations that have an iconic format. Cognition depends on symbolic, language-like representations. If you hold that the difference between perception and cognition is a difference in representational format, then only iconic memory representations are truly perceptual (in the visual domain). Representations stored in working memory, on the other hand, are not perceptual representations.
In the consciousness literature, some – notably, global workspace theorists – hold that the contents of conscious experiences correspond to working memory (or global workspace) representations. Given that working memory representations aren’t perceptual, it means that, if global workspace theory is true, properly perceptual contents are never conscious. Perceptual contents are never conscious... What?! How did we get there? That doesn’t seem right.
What should we do? Quilty-Dunn suggests several possibilities.
The obvious option is to reject the view that conscious contents are the representational contents stored in working memory. Proponents of local theories of consciousness, like Victor Lamme or Ned Block, for instance, would probably go this way.
The second option is to accept higher-order theories. According to at least some versions of higher-order theory, the content of your visual experience (what you visually experience) depends on iconic representations, but those representations don’t become conscious on their own. Instead, you become conscious of their content through higher-order mechanisms (whatever they are). So, no problem here.
I'm not a big fan of the first option. I like the second option (an advantage of the higher-order theory is that it gives you some flexibility on this issue). But if you’re a global workspace theorist – and after all, why not, it’s a good theory – you don’t want that. And, obviously, you don’t want to go with the first option either.
So, this article makes quite clear that you can’t hold both that the difference between cognition and perception is a difference in representational format, and that our (perceptual) experiences depend only on the contents of working memory – or global workspace.
The third option is to reject the view according to which the difference between cognition and perception is a difference in representational format. Instead, you should turn to more “architectural” accounts of the border between perception and cognition, and hold that perception can involve both iconic as well as language-like representations.
As it happens, Quilty-Dunn wrote another paper defending precisely that view. His view is that perception involves "object files" that can incorporate index-like representations of individual objects, as well as abstract, amodal features. If visual perception depends on those object files, then visual perception can’t be defined as involving only iconic representations.
At first, I wasn’t convinced by this view. After all, those object files don’t seem genuinely perceptual. Indeed, object files are used as inputs in inferences, and they don’t reduce to “perceptual or sensor-motor primitives”, as Susan Carey would have it. If so, a simple way to answer Quilty-Dunn’s argument is just to deny that object files are genuinely perceptual. And if object files are not perceptual in nature, why are they relevant to the debate, and why should we care?
Of course, Quilty-Dunn addresses this worry. I'm still not entirely sure where I stand on this, but here's one point I found convincing: it does seem like object files are crucially involved in perceptual phenomena, like transsaccadic memory. The fact that the same objects can be re-identified easily across saccades despite changes in the input is because of this memory. And you wouldn’t hold that transsaccadic memory is not a perceptual phenomenon, would you? Then… there you have it, it seems like you have to hold that object files can be properly perceptual, since they are at the center of crucial perceptual functions. If so, you can’t define the difference between perception and cognition as a difference in representational format, since object files aren’t (purely) iconic representations.
To sum up, if you like the global workspace theory, or if you think that conscious contents are the contents stored in working memory, you’re committed to an “architectural” view of the difference between perception and cognition. But that’s all good, Quilty-Dunn says, because you can accept a kind of “perceptual pluralism”, according to which working memory representations can be considered genuinely perceptual, even if they don’t have an iconic format.
Unfortunately, those "architectural accounts" are under-developed at the moment. When you reject the "representational format" account of the difference between perception and cognition, you know what you lose, but it's unclear what you get. So, I guess we'll have to wait for additional research in this domain.
I thank Jake Quilty-Dunn for reading this before I posted it. Again, congratulations to him for the William James prize!
MM
Looking forward to reading your blog!
ReplyDeleteIt feels like a mistake to put too much significance on the distinction between "perceptual" and "cognitive", at least when looking at things from the perspective of global theories. Doesn't a perception need to have far ranging effects under both HOT and GWT to be a conscious perception? Within that view, it seems like "perceptual" just refers to earlier sensory processing and "cognitive" to later processing, with the distinction being context dependent.
My understanding of GWT is that just about any stage of perceptual processing can win the competition and be broadcast throughout the workspace. Although I suppose that could be restated that any stage has a chance of altering the contents of working memory. But if so, then it does seem like iconic memory *by itself* would never be conscious, only pre-conscious.
All that said, I'm an amateur, so I may be missing something really basic.
Mike
Thanks!
DeleteAs far as higher-order theories go, consciousness is not really a matter of "far ranging effects". But that seems right for GWT. I wouldn't say it's context dependent though. How we define cognitive vs. perceptual is precisely the question. Although I'm not sure many would agree that it's context dependent.
Yes, it seems to me that, if GWT is right, iconic memory contents themselves are never conscious. Those contents need to be "translated" in a format that can be read by other modules. This latter point was emphasized early by Baars, but not so much by more recent GW theorists, like Stanislas Dehaene. I think it's an important point, though. For a simple reason: you want GW contents to be in a format that can be accessed and used by all modules. What would be the point of global broadcast if the stuff that you globally broadcast is in a proprietary perceptual format that can be read only by a specific module? It would be as pointless as broadcasting news in a language that I'm the only one to understand. So, the contents need to be "translated" in a different format before they enter the global workspace. Now, the question is: is *this* representational format, whatever it is, involved in perception, or not? If it turns out it's only involved in cognition, GW would not be very promising, because the representations it says are responsible for consciousness in fact aren't involved in perception. That's how I understand the issue.
MM
That's actually one thing I wonder about the "broadcast" language in GWT, if it isn't just shorthand for something more complicated. It doesn't seem like the brain would really have a global protocol that all modules would understand.
DeleteInstead, it seems like each module would send and receive in its own way, with the "broadcast" merely being content that causes large scale cascades and reverberations, with some connections forming a longer lasting resonance, a binding between certain regions, but each binding being its own type of conversation.
Perception, it seems to me, involves both the representations and the cognition. They seem like two sides of the same coin. The representation is like the skeleton, but the cognition is necessary to extract the meaning, the associations, the categorizations, etc, from that representation. To me, what we call perception requires both, although they're so seamless in our experience they seem like one unified thing.