Blind Sight

Blind Sight

I am not concerned with the empirical facts about so-called blindsight; I shall take them as given. I am interested in the question of description—how should these cases be described? My question is conceptual. The first thing I want to say is that “blindsight” is a contradictory expression: it is not possible to be both blind and sighted. To be blind is to be unable to see; to be sighted is to be able to see—no one can be both at the same time. The facts are that some subjects, human and animal, can respond appropriately to visual stimuli and yet have no conscious awareness of seeing. That is not a contradictory state of affairs: “consciously see” and “process visual stimuli” are not analytically equivalent (synonyms). Blindsight patients can satisfy the latter without satisfying the former. Should we then abandon the expression “blindsight” and speak only of “unconscious processing of visual stimuli”? Then we could not be accused of willful paradox. True, we will not give an appearance of the semi-miraculous (seeing while blind), but we will be speaking accurately, if less sensationally. Or is there some other way of talking that captures the facts as they are without trafficking in contradiction?

To be blind is to be unable to see, so you can’t be blind and yet sighted. The right thing to say is that so-called blindsight patients are not blind: they can see certain things but not consciously see them. They are partially sighted, but not consciously sighted. They are not completely blind. Compare insects: we wouldn’t say an insect with eyes was blind, but it is doubtful that it has conscious visual experience. Its eyes function normally and effectively, but it has no consciousness—there is no contradiction in this state of affairs. A blind insect would be one whose eyes don’t function properly to guide behavior. Insects with vision are “blind-sighted” in the customary sense, though it is wrong to say they are blind. Similarly, humans with “blindsight” are not (completely) blind. But do they see the stimuli they are not conscious of seeing? Is all seeing conscious seeing? For “see” the OED gives “perceive with the eyes”: this seems to apply to insects and human patients with “blindsight”—they perceive with their eyes. They absorb information with their eyes, come to know things, respond appropriately to stimuli. They have what is called unconscious perception; they see unconsciously. However, the OED gives us “become aware or conscious of” for “perceive”: that would appear to suggest that insects and blindsight patients don’t see. Of course, that could just be a mistaken definition—the phrase “unconscious perception” doesn’t seem contradictory. Note, though, that the dictionary definition gives “aware” as well as “conscious”, so perhaps we can say that insects and blindsight patients are aware of the relevant stimuli. They respond to them after all; the stimuli are not like things that fall quite outside the organism’s sensory field. Thus, there can be unconscious awareness. This strikes me as just about acceptable semantically, though I see no objection to speaking of perception without awareness. The phrase “conscious awareness” seems not to be pleonastic, which favors the first alternative (awareness without consciousness). In either case, we can allow for unconscious seeing. Thus, blindsight patients can be said to see the stimuli that don’t enter their consciousness. But–and this is crucial–they are not blind to these seen stimuli; to suppose otherwise is to entertain a contradiction, and is anyway not a correct description of insects and the like. It is better to speak of unconscious seeing not blind seeing in these cases. The patients don’t know they are seeing because of the lack of consciousness, but they are anyway. There is nothing sensational or spooky going on, any more than there is in the case of unconscious insects with eyes. If you prefer, you can describe these patients as having “implicit sight” or “unknown sight”, but don’t say “blind sight”. It’s catchy, but it isn’t true. And haven’t we known for a long time that the brain processes visual stimuli in multiple locations, in principle dissociable? It really isn’t surprising that information gets in through the eyes that is not always consciously recognized—indeed, most of it is probably like that. Consciousness is actually an add-on to all this unconscious visual processing, not a sine qua non. So, let’s drop the gimmicky talk of “blindsight”—there is no such thing.[1]

[1] This is part of a general tendency to speak of neurological abnormalities in gee-whiz terms. Things are often less strange than they are made to appear.