Consciousness and the Social Brain

experimental search has generally been directed to the wrong places in the brain.
    This explorative, experimental approach has tended to focus mostly on visual awareness. How does the brain become conscious of a visual image? To find the neuronal substrate of visual awareness, scientists tend to look to visual circuitry. That is where visual information is processed, and therefore (in the common view at least) that ought to be the site from which the awareness of visual information emerges. By analogy, tactile awareness must emerge from somatosensory circuitry. Emotional awareness must emerge from those brain regions that compute emotions. Awareness of mental arithmetic must emerge from whatever brain circuitryperforms the computations of mental arithmetic. In this common view, the brain must generate consciousness from many places simultaneously like steam rising here and there from leaky pipes. In such a view, it is not absolutely clear why some brain systems generate consciousness and others do not. It is also not clear how all these disparate sources of consciousness can result in what seems, introspectively, to be a unified consciousness. It is even less clear how the property of consciousness, once generated in one place in the brain, such as in visual cortex, can be transmitted to a different site in the brain, such that it can join with other instances of consciousness or flow into and affect speech circuitry. Is consciousness transmitted along neuronal fibers, the same way that regular information is transmitted? If so, then what exactly is the difference between consciousness and information? These issues have remained somewhat obscure.
    In the attention schema theory, consciousness does not, so to speak,
emerge
from information, but instead it
is
information. It is information of a specific type. It is information that describes the process of attending to something. In the case of visual consciousness, the brain binds together information about the visual image that is being attended (
V
), information about the agent performing the attention (
S
), and a schema, or information structure, that roughly represents the dynamics and implications of attention (
A
). A brain-spanning representation is formed,
S
+
A
+
V
. We can report that we have visual consciousness because the cognitive machinery can read that representation and summarize what is described by it. If this theory is correct, then visual circuitry by itself will not provide the answer to visual consciousness. Something else is computing the consciousness part of visual consciousness, the awareness, the
A
part of
S
+
A
+
V
.
    The search for the brain basis of consciousness has tended to target sensory areas where, according to the attention schema theory, the answer is not to be found. Perhaps for this reason, this experimental approach has not fared well. It has certainly failed to uncover a coherent explanation of consciousness. The experiments and observations are nonethelessinteresting and important. The attention schema theory, if it is correct, had better be consistent with these experimental observations.
    The following sections briefly summarize two common experimental approaches to the neuronal correlates of consciousness. These studies look for events in the brain that correlate with the presence or absence of visual consciousness.
Binocular Rivalry

    One popular experimental paradigm for studying consciousness involves a visual trick called binocular rivalry. 1 – 3 In binocular rivalry, two different images are presented simultaneously, one to each eye. People report that they consciously see one or the other image, almost never both. The percept switches from image to image somewhat unpredictably every few seconds in what is called a bistable fashion. If you have an image of Dorothy presented to one eye and the Wicked Witch of the West to the other eye, you will see Dorothy; a moment later she will fade and give rise to the wicked witch; and in another moment, the witch will fade and cede the visual field once again to Dorothy.
    The logic goes as follows: if you can find the consciousness part of the brain, then neurons in that brain area should change their activity levels every few seconds, tracking the image that is currently in consciousness. When the person is aware of Dorothy, neurons in that brain area should respond as though only Dorothy were present. When the person is aware of the witch, the neurons should respond as