Susan Blackmore’s Consciousness: A Very Short Introduction may have been the first book I read on consciousness many years ago. Recent conversations rekindled my interest in her views.
I’m pretty sure her discussion of consciousness as an illusion was the first time I had encountered that idea. Strong illusionists such as Keith Frankish and Daniel Dennett generally take the stance that phenomenal consciousness doesn’t exist. Blackmore’s illusionism seems like a weaker form, that consciousness exists but isn’t what it seems. And by “consciousness” she stipulates in one of her books that she usually means phenomenal consciousness.
Of course, the difference between a strong and weak illusionist can be seen as mostly definitional. Strong illusionists generally take “phenomenal consciousness” to refer to the metaphysically intrinsic, private, ineffable, and incorrigible concept discussed by Nagel, Block, Chalmers, and other non-physicalists, one that is ontologically separate from access (functional) consciousness. A weak illusionist sees this version as illusory, but is more willing to just consider the illusion itself a reconstructed version of “phenomenal”.
But Blackmore, in her discussions of illusion, often focuses on other issues. One is the Grand Illusion, our impression of how much visual information we take in. If you look around in whatever room or setting you’re currently in, your impression is likely to be that your visual field contains all the details in front of you.
However, there are good reasons to conclude that impression is an illusion. One is that the retina doesn’t really work like a camera. It has a central region, the fovea, which has high acuity (resolution) and high color discrimination. But as we move out from that small central region, the acuity drops dramatically and color discrimination mostly disappears.
In addition, your visual field has a blind spot in it. This is the spot where the axons from the ganglion cells in the retina feed into the optic nerve. There are no photoreceptors in this location, and so no vision. You can detect this blind spot for yourself by holding your left thumb out at arm’s length, closing your right eye, and looking at where your thumb is, then without moving your eye, slowing move your thumb to the left. At some point, all or a portion of your thumb should disappear. (It may take a few tries. The Wikipedia article also has another way of seeing it.)
Why don’t we perceive the world with a small sharp colorful center and increasing colorless blurriness out to the sides, along with a hole in it all? One is that these are not limitations of a window we’re looking through, but constraints on perception itself, and we don’t perceive what we don’t perceive. The other is that our eyes are constantly moving, often in reflexive saccadic movements we’re not aware of, allowing us to take in any detail we want to focus on.
That last point is important, because when you looked at the room or setting your were in, you didn’t have time to scan the entire thing with your fovea. So any impression of taking in the whole thing is wrong. Often this is described in the popular press as the brain “filling in” the details. But there’s no evidence for that. We just don’t take in those details. Our impression is that we do, because the detail is always there when we check, by moving the focus of our eyes to a particular spot.
Other related issues Blackmore discusses are inattentional blindness and change blindness. Inattentional blindness refers to the fact that we’re generally blind to things we’re not attending to. The classic example is the ball throwing video, where (spoiler alert) participants are focused on counting the ball throws between white t-shirted players, so that they miss the gorilla that walks through the scene. And a good example of change blindness is the video I shared the other day.
Blackmore’s goal in discussing these issues is, I think, to make us realize how wrong we can be about what information we actually take in. And to soften us up for her big one: delusionism. She asks us to consider, are we conscious right now? Of course, the answer is generally going to be yes. But what about a few moments ago, when we weren’t thinking about our consciousness, when we weren’t introspecting?
Blackmore points out that the only way we know our consciousness is through introspection. So how do we know it’s there when we’re not introspecting? Attempting to ascertain whether it is, is like opening the refrigerator door to see if the light is on when the door is closed, or to use an example from William James, attempting to turn up the light to get a better look at the dark.
Maybe a unified model of self, attention, and perceptions is put together just when we introspect, but when we’re not, processes continue in the brain in parallel with no distinction between conscious and unconscious processing. Blackmore points out that this is consistent with the neurological evidence, which shows no inherent difference between conscious and unconscious processing.
If this is true, then the very idea of a stream of consciousness is misguided, and we are massively confused about the extent of consciousness in nature. In this view, consciousness appears to only exist in humans, and then only some of the time. It would make it meaningless to ponder what it’s like to be a bat, or anything else.
My take on this is that, as usual, it depends on how we define “consciousness”. As a functionalist, I think consciousness is functionality, but which functionality in particular counts as “conscious” doesn’t seem like a fact of the matter. Which is why you usually get discussions of hierarchies from me.
In particular, I think the perceptual one is worth reviewing here. In this hierarchy, consciousness can be the processing that results from:
- Deliberative attention
Blackmore’s delusionism equates consciousness with 1, which I’ve been tempted to do myself in the past. But it leads to a view of consciousness that is very sparse. If we hold out for self reflective awareness as the standard, then it’s where we seem to end up.
On the other hand, if we equate consciousness with 2, then the stream of consciousness, as the sequence of things attended to, is much easier to establish, both in humans and animals. We just have to realize that this isn’t the full package we have while we’re contemplating our own mental life.
What do you think of Blackmore’s version of illusionism? Or delusionism? Or my take on it?