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A Phenomenological Analysis: Consciousness as Integrated Information
The integrated information theory (IIT) of consciousness claims that, at the fundamental level, consciousness is integrated information, and that its quality is given by the informational relationships generated by a complex of elements (Tononi, 2004). These claims stem from realizing that information and integration are the essential properties of our own experience. This may not be immediately evident, perhaps because, being endowed with consciousness most of the time, we tend to take its gifts for granted. To regain some perspective, it is useful to resort to two thought experiments, one involving a photodiode and the other a digital camera.
Information: the photodiode thought experiment
Consider the following: You are facing a blank screen that is alternately on and off, and you have been instructed to say “light” when the screen turns on and “dark” when it turns off. A photodiode—a simple light-sensitive device—has also been placed in front of the screen. It contains a sensor that responds to light with an increase in current and a detector connected to the sensor that says “light” if the current is above a certain threshold and “dark” otherwise. The first problem of consciousness reduces to this: when you distinguish between the screen being on or off, you have the subjective experience of seeing light or dark. The photodiode can also distinguish between the screen being on or off, but presumably it does not have a subjective experience of light and dark. What is the key difference between you and the photodiode?
According to the IIT, the difference has to do with how much information is generated when that distinction is made. Information is classically defined as reduction of uncertainty: the more numerous the alternatives that are ruled out, the greater the reduction of uncertainty, and thus the greater the information. It is usually measured using the entropy function, which is the logarithm of the number of alternatives (assuming they are equally likely). For example, tossing a fair coin and obtaining heads corresponds to log2(2) = 1 bit of information, because there are just two alternatives; throwing a fair die yields log2(6) = 2.59 bits of information, because there are six.
Let us now compare the photodiode with you. When the blank screen turns on, the mechanism in the photodiode tells the detector that the current from the sensor is above rather than below the threshold, so it reports “light.” In performing this discrimination between two alternatives, the detector in the photodiode generates log2(2) = 1 bit of information. When you see the blank screen turn on, on the other hand, the situation is quite different. Though you may think you are performing the same discrimination between light and dark as the photodiode, you are in fact discriminating among a much larger number of alternatives, thereby generating many more bits of information.
This is easy to see. Just imagine that, instead of turning light and dark, the screen were to turn red, then green, then blue, and then display, one after the other, every frame from every movie that was ever produced. The photodiode, inevitably, would go on signaling whether the amount of light for each frame is above or below its threshold: to a photodiode, things can only be one of two ways, so when it reports “light,” it really means just “this way” versus “that way.” For you, however, a light screen is different not only from a dark screen, but from a multitude of other images, so when you say “light,” it really means this specific way versus countless other ways, such as a red screen, a green screen, a blue screen, this movie frame, that movie frame, and so on for every movie frame (not to mention for a sound, smell, thought, or any combination of the above). Clearly, each frame looks different to you, implying that some mechanism in your brain must be able to tell it apart from all the others. So when you say “light,” whether you think about it or not (and you typically won't), you have just made a discrimination among a very large number of alternatives, and thereby generated many bits of information.
This point is so deceivingly simple that it is useful to elaborate a bit on why, although a photodiode may be as good as we are in detecting light, it cannot possibly see light the way we do—in fact, it cannot possibly “see” anything at all. Hopefully, by realizing what the photodiode lacks, we may appreciate what allows us to consciously “see” the light.
The key is to realize how the many discriminations we can do, and the photodiode cannot, affect the meaning of the discrimination at hand, the one between light and dark. For example, the photodiode has no mechanism to discriminate colored from achromatic light, even less to tell which particular color the light might be. As a consequence, all light is the same to it, as long as it exceeds a certain threshold. So for the photodiode, “light” cannot possibly mean achromatic as opposed to colored, not to mention of which particular color. Also, the photodiode has no mechanism to distinguish between a homogeneous light and a bright shape—any bright shape—on a darker background. So for the photodiode, light cannot possibly mean full field as opposed to a shape—any of countless particular shapes. Worse, the photodiode does not even know that it is detecting a visual attribute (the “visualness” of light) as it has no mechanism to tell visual attributes, such as light or dark, from non-visual ones, such as hot and cold, light or heavy, loud or soft, and so on. As far as it knows, the photodiode might just as well be a thermistor—it has no way of knowing whether it is sensing light versus dark or hot versus cold.
In short, the only specification a photodiode can make is whether things are this or that way: any further specification is impossible because it does not have mechanisms for it. Therefore, when the photodiode detects “light,” such “light” cannot possibly mean what it means for us; it does not even mean that it is a visual attribute. By contrast, when we see “light” in full consciousness, we are implicitly being much more specific: we simultaneously specify that things are this way rather than that way (light as opposed to dark), that whatever we are discriminating is not colored (in any particular color), does not have a shape (any particular one), is visual as opposed to auditory or olfactory, sensory as opposed to thought-like, and so on. To us, then, light is much more meaningful precisely because we have mechanisms that can discriminate this particular state of affairs we call “light” against a large number of alternatives.
According to the IIT, it is all this added meaning, provided implicitly by how we discriminate pure light from all these alternatives, that increases the level of consciousness.
This central point may be appreciated either by “subtraction” or by “addition.” By subtraction, one may realize that our being conscious of “light” would degrade more and more—would lose its non-coloredness, its non-shapedness, would even lose its visualness—as its meaning is progressively stripped down to just “one of two ways,” as with the photodiode. By addition, one may realize that we can only see “light” as we see it, as progressively more and more meaning is added by specifying how it differs from countless alternatives.
Either way, the theory says that the more specifically one's mechanisms discriminate between what pure light is and what it is not (the more they specify what light means), the more one is conscious of it.
I find this interesting - and of course it goes on.
