What do we need to know about consciousness? Which aspect of it is most mysterious? What do we want philosophy, psychology, neuroscience, computer science, or even physics to tell us about consciousness that we do not already know? The answer to that question may vary from person to person. To me it is this very simple thing: why do I see? Why do I have conscious experiences whenever I open my eyes? What makes the 1.5 kilograms of protein and fat in my head give me the wonderful sensations I experience every day, from the second I wake up until the moment I fall asleep?
The point is probably best illustrated by the difference between a digital photo camera and the human mind. A camera nowadays can do wonderful things. It can record an image at extreme resolutions, with the right focus and exposure, all by itself. It can identify a face, putting it in a frame on the screen, and writing the name below it of the person it recognizes. You can leave it to push the button at the moment everybody smiles. Connect it to a computer, and it will detect emotions, recognize objects, or read handwriting on a letter. Surveillance cameras can detect suspicious movements or strange behaviours in crowds, outperforming human night-guards or intelligence agents. There is one big difference between the camera and the human mind, though. The camera does not see.[1] I do. And so does the night guard, most of the time. It is this aspect of visual processing that is in need of an explanation. Not the fact that I recognize the person in front of me, can read his emotions, talk to him, or pick up the cup of coffee he gives me. I can vaguely understand how my brain enables me to do that. What I do not understand is how it is that I see all those things.
Is that the “hard problem” all over? Am I talking Qualia? Not in the strict sense. In its original formulation, the hard problem would argue that there is no function, no neural process whatsoever that could ever explain conscious sensations (Chalmers 1995). Functions explain functions, but not the fact that I see. Qualia are defined as ineffable aspects of information: the redness of red, stripped of every possible functional property or reactive disposition. And with that comes the whole charade of inverted spectra, colour scientists called Mary, and explanatory gaps. Which didn’t get us all that far—so let’s not chase that unicorn again.
It’s not that I don’t want to address the hard problem, or bridge the explanatory gap. That is in fact exactly what I am after (Lamme 2010a, 2010b). But I would like to leave that for later. What we need to recognize, first, is that there must be some functions and some neural processes that are more closely connected to seeing than others (Crick & Koch 1998, 2003). For example, it is fairly reasonable to assume that an understanding of the neural basis of a reflexive motor response—like the pulling away of your hand when it touches fire— does very little towards explaining consciousness (Lamme & Roelfsema 2000; Lamme 2006). Other functions may offer a better gateway. For example because they explain some fundamental aspect of seeing (Seth 2010), such as its unity, or because they coincide with the difference between conscious visual processing and visual processing that occurs “in the dark” (Lamme 2010a, 2010b). In trying to bridge the explanatory gap, I think it is important to first find the right tree up which to bark. We must first identify the exact boundaries between conscious and unconscious processing. The hard problem can then be attacked afterwards. Or maybe that whole explanatory gap will vanish right before our eyes once we are there.
This paper is about exactly that. Let’s find the visual functions and neural processes that take us as close as possible to the hard problem, as close as possible towards explaining why we humans see, while photo cameras do not. And let’s avoid barking up the wrong tree.