A Stand of Yellow Birch Trees
Not long ago I was at the top of a hill in the early evening of a sunny day, looking down on a pine forest, and I was amazed to see a patch of luminous glowing yellow birch trees surrounded by the dark pines. I thought surely it’s far too early for the leaves to turn—and I’ve never seen any birch trees around here anyway. But then I suddenly saw the spectacle for what it was. These were not different trees at all; it was just a small area of the fairly uniform pine forest directly illuminated by the sunlight shining through a gap between the hills, the rest of the forest being in shadow. Neither the trees nor the light had changed, but in that moment the bright yellow was extinguished, leaving just the ordinary warm green that I’m used to seeing around here in the evenings. What I found incredible was the difference in intensity between these colours, though they turned out to be the very same colour. I looked upon the scene in its new, real aspect and tried to see the green as bright yellow once again, but I couldn’t recapture it, because I could no longer see the pine trees as birch trees.
Perception is meaningful through and through. Far from a mysterious spectating consciousness passing judgment on processed sense-inputs, it’s significance all the way down.
These considerations are sometimes explained in terms of stuff in the head:
“All we’re actually doing is seeing an internal model of the world; we’re not seeing what’s out there, we’re seeing just our internal model of it. And that’s why, when you move your eyes around, all you’re doing is updating that model.”
—David Eagleman (Source)
To this way of thinking, my brain did the best it could at the time to construct a model of reality, and came up with bright yellow birch trees in a sea of pines; and a few seconds later it managed to update the model to better integrate it into my experience, or to better represent reality. It’s a tempting way to think about it, because it neatly does away with questions about how we can be said to see things in the world while our senses are so fickle and unreliable, while what is perceived can switch without warning between exclusive aspects. The simple answer here is that we don’t see things in the world.
The trouble is that Eagleman’s comment is not, despite his scientific credentials, a neutral report of scientific results. It’s an interpretation and a guiding paradigm. An alternative, which is equally well supported, is to say that neural activity, rather than constructing reality as an internal model, is a central component in the sensorimotor organization of a perceiver’s bodily engagement with its environment, such that the activity of the body and the stimulation of the senses can be integrated and continually corrected. The intrusion into this account of a model—rather than the world—as the very thing perceived, and of perceived reality as internal (“in the head”), are just the intrusions of bad philosophy. We do see what’s out there, and we do it in the only way we can: with our bodies—including the brain.
Lying beneath the paradigm of the internal model is the notion that if anything intervenes between what are taken to be the two opposite poles of perception—namely subject and object, consciousness and the world—then perception is indirect and essentially impure. That is, we never really get at the things themselves, because we’re trapped in a sensory pod, only able to access representations of a great outdoors that is forever shut off from us. This is an old notion, and it no longer stands up.
This can be seen with a small adjustment: instead of thinking about the body and the senses and the brain as forming a distorting medium intervening between our inner selves and outer reality, we can think of them more ecologically, as guaranteeing our access to reality by allowing us to get a grip on our environment. If the contingent physicality of perception entails that we never perceive the world as it really is, but only from a particular perspective, then there must be a conceivable pure kind of perspectiveless perception in which everything is seen in all its possible aspects all at once. Actually existing perception thus falls short of an impossibly high standard of acquaintance. And this is the problem. What right have we to posit a Godly direct knowledge as the gold standard of perception? What, exactly, is being distorted?
To ask that perception be unmediated and pure for it to successfully make contact with reality is to ask that we should see without seeing or hear without hearing. It is to remain committed to a philosophical chimera: absolute knowledge, the Mind of God. But if we can ditch this notion of an unattainable superperception, as surely most neuroscientists now do, then the physical nature of perception can be seen to be, not a barrier, but precisely what opens up the world for us as a field of possible activity.
With God once again disposed of, what remains is to properly account for my illusion without recourse to internal objects of perception, distorting sense-organs and creative brains. For this we now have many promising avenues of research informed by phenomenology—such as neurophenomenology, enactivism, embodied cognition, and the modeling of perception and cognition using dynamical systems theory—and I can’t do more than give a sense of it all.
We always seek to integrate things we see into a coherent whole, to get a grip on our environment in a specific kind of way. We all know the occasional feeling of being without a coherent world, of being not yet properly geared into an environment, as when we see a shape but can’t tell whether it’s a man or a parking meter, a spot on the window or a plane in the sky, or when we wake up in a strange house disorientated, trying to jolt ourselves into spatial reality. These moments are dissonant and unstable: they demand resolution and equilibrium. This means that we always in normal, successful perception see things under an aspect: as a spot on the window, as the door that opens on to the hallway, as a patch of autumnal birch trees, as a face, as a duck—or is it a rabbit?
This is essential to successful activity. We must be geared into the world to be able to move about in it, to reach out and touch things, to judge distances and sizes. This is achieved not only with the brain, but with the brain as part of a bodily system always seeking to maintain optimal sensorimotor engagement. We move our heads and eyes to see things correctly—try keeping your eyeballs fixed and see how much sense you can make of your environment.
When I saw the trees as bright yellow birches, I was seeing things in a specific kind of way, that is, I was geared into the world in a way that made sense as a whole. This is not the same as saying, and it does not entail, that I was not seeing real trees but merely a mental or neural model. I was seeing real trees under an aspect that my perceptual system made possible, partly thanks to my memory of bright yellow birch trees. I wasn’t seeing birch trees, but simply because both aspects seemed equally strong at the time it doesn’t follow that I also wasn’t seeing pine trees. I was seeing pine trees as birch trees.
As for the details, have a look at this page on the sensorimotor theory of consciousness.