Consciousness and the Social Brain

all, blind people, with no visual cues about someone else’s gaze direction, still understand other people’s attention.
    As diagrammed in Figure 2.6 , the proposed attention schema can
use
gaze direction as a cue, but does not necessarily do so. It brings together a totality of evidence to constrain a rather rich and sophisticated model of someone else’s attention. It can use that model to help understand other people and predict their behavior. I am proposing that the same machinery used to model another person’s attentional state in a social situation is also used to model one’s own attentional state. The benefit is the same: understanding and predicting one’s own behavior. The machinery is in this sense general.

    FIGURE 2.6
The attention schema, the hypothesized model of attentional state and attentional dynamics, relies on information from many sources. Diagrammed here are some of the cues from which we reconstruct someone else’s attentional state.

    Where in the brain should we look for this proposed attention schema? The theory makes three broad predictions about the brain areas involved.
    First, a brain system that constructs the attention schema should be active when people engage in social perception. It should be involved in monitoring or reconstructing other people’s mind states, especially reconstructing the state of other people’s attention.
    Second, a brain system that constructs the attention schema should somehow track or reflect a person’s own changing state of attention.
    Third, when that brain system is damaged or disrupted, awareness itself should be disrupted.

    FIGURE 2.7
Two areas of the human brain that might be relevant to social intelligence.

    Do any areas of the brain satisfy these predictions? It turns out that all three properties overlap in a region of the cerebral cortex that lies just above the ear, with a relative emphasis on the right side of the brain. Within that brain region, two adjacent areas have been studied most intensively. These areas are shown in Figure 2.7 . (A scan of myown right cerebral hemisphere, by the way.) They are the superior temporal sulcus (STS) and the temporo-parietal junction (TPJ). These areas are probably themselves collections of smaller, specialized subunits that presumably work in a cooperative fashion and interact with larger, brain-wide networks. I will describe the details of the TPJ and the STS in later chapters. Here I merely note in brief that they combine the three key properties predicted by the attention schema theory. First, these areas are recruited during social perception. Second, they track one’s own state of attention. Third, damage to them leads to a devastating clinical disruption of awareness. Each of these three properties was discovered and studied separately, and the collision of the three properties in one region of the brain has caused some controversy. How can such diverse, seemingly unrelated properties be reconciled? The attention schema theory may help to solve the riddle by fitting the many results into a single framework.
    In the present theory, the
content
of consciousness, the stuff
in
the conscious mind, is distributed over a large set of brain areas, areas that encode vision, emotion, language, action plans, and so on. The full set of information that is present in consciousness at any one time has been called the “global workspace.” 25 , 26 In the present theory, the global workspace spans many diverse areas of the brain. But the specific property of awareness, the
essence
of awareness added to the global workspace, is constructed by an expert system in a limited part of the brain, perhaps centered on the TPJ or STS and perhaps involving other brain regions. The computed property of awareness can be bound to the larger whole. As a result, the brain can report that awareness is attached to a color, that awareness is attached to a sound, that awareness is attached to an abstract thought.
    This account of consciousness gives an especially simple explanation for why so much information, the majority of processing in the brain, can never reach consciousness. Much of the information in the brain may not be directly linkable to the attention schema. Only brain areas that are appropriately linkable to the attention schema can participate in consciousness.
    Even information that can in principle be linked to the attention schema might not always be so. For example, not everything that comes in