Something I've been meaning to write about for a couple of weeks now: object meaning as filling-in, and how this idea is the explanation for cases of
deja trompe.
We return to the idea that the visual field is a stack of properties that develop from one another along a relatively rigid hierarchy. So, a certain configuration of brightnesses, which can be seen as such (as brightnesses, or darknesses, or colors), can also be seen as an edge or some other broadband
feature. In fact, given certain configurations of colors, given broadband percepts are compulsory and there is no choice but to see them. However, they do not exclude the more local aspects that seem to
compose the features. From edges we go to surfaces and depths, and from there to objects and meanings and utilities.
All these levels of the visual hierarchy are experienced simultaneously and constitute conscious qualia - we are experientially aware of points of color or brightness, and we are aware of edges and lines independent of the surfaces they bound, and we are aware of surfaces independent of the objects the bound, and we are aware of objects (in the sense of depthful 'thingness') independent of the meanings they bound (what they "are"). But the independence of these qualia exists only in their separability, because in normal experience they are not causally independent - when a given configuration exists, the other levels are evoked compulsorily, and so qualia are correlated between levels.
Illusion often consists of violations of these correlations. So, we will see illusory contours where there are no variations in color or brightness to constitute them.
Deja trompe, as I have described it, is seeing an object as something other than what it "is", and doing so repeatedly, involuntarily, and being aware of this repeated mistake (this is the literal meaning of the term). In the case of illusory contours, the normal correlation or association between patterns of color and edges can make one feel that something at that level
is seen, i.e. that there are color or brightness qualia there, though I don't see them (what I see is an edge without any color variation). On the other hand, we certainly see the colors in the watercolor illusion, or in other filling-in effects, so it seems that it does happen that we can be tricked into generating qualia without the normal hierarchical causes, both up
and down (and within) the hierarchy.
In seeing an object for something that it is not, what is happening? When I walk through the hallway to the kitchen, and see my cat sitting on the floor in one of her usual spots, looking up at me as I pass, only to realize in a fraction of a second that no, that's not my cat, those are my
boots - what am I actually seeing, during the duration of the mistake? I see something there, a thing with similar color and size and shape as a cat or a pair of boots, and in a suitable location for either. So, am I seeing a cat, and then seeing a pair of boots? Or am I seeing a pair of boots, and
thinking it's a cat, and then
thinking it's a pair of boots? Or am I seeing something indeterminate and relatively formless, that can be either thing (
deja trompe is really a creature of peripheral vision, so crowding is of course a thing)? What is seeing? What is thinking
it is?
Obviously, I have an opinion. And, being a kind of expert in this sort of thing, it's an informed opinion. I think that seeing boots for cat, my low-level qualia are entirely boots-driven, so in that sense, I am seeing boots. If you put the boots and the cat side by side at the same location in the visual field, I am confident that I could discriminate them, though there's a test there. Actually, that's a nice idea: take the objects that are confused in a
deja trompe, and measure their actual discriminability. So it could be that they
are relatively indiscriminable, and what is seen is relatively indeterminate and formless.
Actually, whether the low-level qualia are distinctly bootslike or indeterminate doesn't matter much to my interpretation, just shifts things around a little. What is certainly not happening is that the low level qualia are going from being more catlike to more bootslike, or that they are changing
at all. That is the striking thing here: that the low-level qualia do not change, although they
seem to change, in what is either a metacognitive or memorial judgment. What is changing is the
meaning of what is seen, and that is what is so interesting here. Because the low-level qualia are not sufficiently specifying the identity of the object, it is briefly mis-specified, something which almost never happens in normal visual experience. Once you know what something is, you virtually never mistake it for something else, except in cases where you do, and when that happens you note it or mention it to whoever else is in the room, because it's so surprising.
When it happens,
deja trompe gives a strong impression that
what is seen is changing from one thing to another. However, it only makes sense that this is happening at the highest levels. The lower-level qualia, I will maintain (when given the chance) are more determined by the sensory input, and the later qualia are determined by the lower-level qualia (and certainly also by other mechanisms that do not present themselves in consciousness). So, through this chain, errors or lack of specificity can build up, and you wind up with a mistake,
at the top.
What it comes down to is that
meaning, i.e. what a thing
is, is a sort of filling-in, where in exactly the same way as the watercolor effect, but much more solidly and more vigorously, the multi-level boundaries of an object prompt it to be visually filled with meaning. I mean this literally, and I think it is obviously true: when you see a scene filled with objects, all of which you recognize, their identities are
there within, in the same locations as the objects. So an object made of a certain size, and in a certain spatial location, and colored black and brown, is painted with
bootsness, and that is what makes it
boots. If I mis-paint it as
cat, that is what makes it
cat - nothing about the lower-level qualia, the shapes or the colors or the general configuration of the object's visual structure, are really directly associated with that meaning. You can destroy certain parts of my brain, and I will still see things as objects, but I won't know what they are.
So, these instances of mistakes in identification are interesting in how they reveal the dissociation between objects in themselves, and objects as they have
meaning. An object in itself is still a perceptual construct, but it is meaningless. It only as existence in relation to other perceptual constructs. This is a middle place between the physical
stuff to which the object presumably refers, and which is even more meaningless in that it has no relations at all to other stuff - there is simply stuff, and any effort to clump it into
this stuff or
that stuff is exactly that:
effort, something done by an agent. So the object in itself is the way the brain deals that stuff into a usable form, and the
meaning of the object, what the object
is, is the set of all known relations of the object in
higher levels: past and future, the stuff of cogitation and memory, beyond perception that exists only in the immediate moment.
That's enough of this. Just been thinking about these things on the train lately, needed to get it out of my system (or at least articulate it into something interesting - the discrimination experiment based on actual instances of
deja trompe might actually be a good idea).
