I’ve posted on HOT (higher order thought theories of consciousness) before, but there’s a new paper out covering the basics of these types of theories. Since first reading about HOT many months ago, the framework has been growing on me. The paper is not too technical and I think would be accessible to most interested readers.
In general, HOT is the idea that first order representations, the sensory images formed in early sensory areas of the brain, such as in the visual cortex, are not by themselves sufficient for being conscious of their contents. We can hold and react to such representations unconsciously.
In order to be conscious of the representation, a second or higher order representation is needed, a representation about the first representation. Inner awareness comes from these higher order representations accessing the first order representations.
Under most HOT theories, the higher order representations are in the prefrontal cortex. This puts the PFC at the center of consciousness, a contentious view. Although there is an openness to the possibility that some higher order representations might be in the parietal or temporal lobes.
I was a bit surprised that the paper described GWT (global workspace theory) as a first order theory. GWT posits that for a perception to enter consciousness, it must be broadcast into the global workspace. I would have thought that GWT was agnostic about how the information from the representation made it to the various cognitive modules.
I envisioned that GWT might provide a big picture view of what was happening, with HOT providing the details, and each of the cognitive modules holding their own versions of the representation, that is, their own representation of the initial one, tailored to their own needs. But apparently GWT is more specific in its views about how the information is broadcast and received. If so, that threatens to weaken GWT in my eyes, making it into a sort of data bus that I’m not sure matches the actual biology.
One of the things I do wonder about HOT is how accurate it is to call the higher order representations… representations. It doesn’t seem controversial to say there is processing happening in other regions that make use of the information from the first order representations, or that being conscious of the representations requires processing outside of them. But saying the information held by this other processing itself amounts to a representation might be an oversimplification.
Indeed, the division that many of these theories make between the representations and the processing that happens about the representations has long struck me as artificial. I suspect there isn’t any clean line. The representation probably gradually morphs through processing layers to being processing about associations of the representation and other related information.
Still, HOT strikes me as a productive way to think about inner experience. We just have to remember that the higher order representations are not just mirror images of the first order ones, but are heavily tailored to the needs of the regions in which they exist. Representations in the prefrontal cortex are likely integral components of action plans.
Interestingly, reading this paper, I realized that another theory I’ve long been fond of, Michael Graziano’s AST (attention schema theory), is itself a type of higher order theory, although I haven’t seen it described anywhere as one. AST posits that the brain holds a representation, a schema of the process of attention, and that inner awareness results from this representation.
Graziano doesn’t see the schema as being in the prefrontal cortex, but in regions along the border between the parietal and temporal lobes, although the prefrontal cortex may be involved. And again, various HOT theories seem open to the possibility of some higher order representations being outside of the prefrontal cortex.
HOT theories are almost certainly not the final word, if for no other reason than they differ on various points, and I suspect the devil is in those details, but the overall viewpoint strikes me as having promise.
Unless of course, I’m missing something?