God Soul Mind Brain

a part of the brain whose computations are totally opaque to consciousness? Only the output of box 2 reaches consciousness, not the computations within it. The reason why these studies are interesting is that some visual signals reach consciousness and others do not. In the hypothesis of Christof Koch, visual information is compressed or summarized in packets of information that are communicated to a central processor. Conscious experience somehow results when those packets of information arrive at the central processor. I agree with that general description. Here I suggest that this nexus, this key processor that is receiving summary packets of information, that results in conscious experience, is specifically the circuitry for social intelligence. It is the brain’s expert at computing the property of awareness.

    Some visual information reaches this circuitry and some does not. One of the most striking examples in which visual information is blocked from reaching consciousness is called “change blindness.” Suppose I show you a picture of a beach scene. You look at it for a moment, and then I take it away and give you a second picture. I ask you, “Is anything different?” You might stare for a moment and conclude, “No, it’s identical to the last one.” I put the two pictures side by side to show you, and you still might not be able to see any differences. Finally I point to one of the differences: perhaps a beach chair is moved to the left in one picture. The change is obvious once it is pointed out. You missed it initially only because you happened to be attending to other features in the scene. Images outside your focus of attention usually do not reach consciousness.

    This example of visual attention makes sense in the context of Diagram 4-1. If box 2 produces a weak output because it is processing an unattended object, then the output signal has relatively little effect on boxes 1 and 3. The signal strength is too low to be detected in the background clutter of other signals. Boxes 1 and 3, failing to receive the signal, cannot incorporate it into any model of mind. In constructing a self model, boxes 1 and 3 must build a roster of items that are, according to the model, within your awareness. If a particular visual signal coming from box 2 is too weak to impact boxes 1 and 3, then the signal cannot be incorporated into that list. When boxes 1 and 3 are queried about what items are in your awareness, they will fail to report that visual signal. In this specific way, the visual signal fails to penetrate consciousness. But if box 2 produces a strong output (perhaps it is processing a colorful bird that is directly in the focus of attention), then boxes 1 and 3 receive that stronger signal. When queried about what items are within your awareness, boxes 1 and 3 will be able to report on that stronger visual signal. In this way, a strong visual signal from box 2 penetrates consciousness.

    Another commonly studied example of visual awareness is called binocular rivalry. In this phenomenon, two different visual images are presented, one to each eye. Due to an apparent competition between the signals within the brain, people report being consciously aware of one or the other item, but not both. Awareness switches somewhat unpredictably, every few seconds, from the image in one eye to the image in the other eye. In the present formulation, the explanation is that a strong competition between the two signals occurs within the visual system; the competition causes one signal to rise and the other to fall; the dominant signal is strong enough to impact the circuitry for social perception; the weaker signal cannot. In this view, binocular rivalry is not itself a part of visual consciousness. Instead it represents a filtering mechanism through which information must pass before it can arrive at the machinery responsible for conscious awareness.

    For this general type of reason, some of the work on consciousness has focused on exactly how signals in visual areas of the brain are boosted to be stronger. Visual attention is one way of boosting signals. The synchronized activity of many neurons can boost a signal. The pulsing activity of groups of neurons may boost signals. Reverberation of signals going up and down from perceptual brain areas to cognitive brain areas and back again may boost signals. All of these mechanisms have been examined as a way of boosting the signal coming out of box 2. Boxes 1 and 3 are