Consciousness and the Social Brain

particular, quirky set of properties to awareness. It accounts for awareness in all the right domains, such as vision, touch, emotion, ideas, and memories. It accounts for both self-awareness and awareness of the external world. It allows for awareness in people who might be socially challenged.
    If the attention schema theory were solely a tweak or refinement of the social theories of consciousness, avoiding some of the typical pitfalls of that common previous approach, it would probably still deserve consideration. The theory, however, has a much broader scope. The next six chapters, most of the rest of this book, take up a great range of topics in consciousness research and in brain research. These topics include previous theories of how the brain producesconsciousness, how social intelligence is organized in the brain, how damage to the brain may disrupt consciousness, how specific neurons in the brain may help mirror the thoughts and actions of others, and many other subjects. All of these topics relate in a fundamental way to the attention schema theory. The theory may be able to pull together a large set of otherwise disparate findings and hypotheses into a single framework.

11
Consciousness as Integrated Information

    In the previous chapter I discussed one of the most common theoretical approaches to consciousness—the social construction of consciousness. A second common theoretical approach is to attribute consciousness to informational complexity and in particular to the linking, or binding, or integration of information in the brain. The social approach and the integrated information approach to consciousness are quite different and in some ways have been viewed as rivals. Yet the attention schema theory could be seen as a way of fusing the two approaches.
    In the attention schema theory, awareness is a computed feature. It is descriptive information—call it information set
A
. To be aware of
X
is to bind or integrate the information that depicts
X
with the information set
A
. When you report that you are aware of
X
, it is because cognitive machinery in your brain has accessed that large, brain-spanning set of information,
A
+
X
, and is summarizing it. You are reporting that
X
comes with the properties of
A
attached to it. The attention schema theory works only so far as the proposed attention schema can be bound to other chunks of information. It is an integrated information approach to consciousness just as much as it is a social approach.
    This chapter describes the integrated information approach to consciousness, beginning with the early versions of that line of thinking, and then discussing some of the potential strengths andweaknesses of the approach and how it may relate specifically to the attention schema theory.
Integrated Information Theories

    In 1983, Baars 1 , 2 proposed the global workspace hypothesis, one of the first well-articulated theories of consciousness as integrated information. In that theory, information spanning many brain areas can be linked or bound into a single, coherent whole, and that brain-wide pool of information forms a global workspace that encompasses the contents of consciousness.
    The neural basis for binding information across widespread brain areas is not yet known, but one hypothesis has been investigated in some depth. In 1990, Singer and colleagues 3 were studying the visual system of the cat and discovered that under some conditions the neurons were active in rhythmic bursts. These bursts occurred about 40 times per second in a regular oscillation. Moreover, different neurons that were spatially separated from each other in the cortex could oscillate in synchrony with each other.
    In theory, two neurons that are active in synchrony form a powerful information unit. A single neuron, sending a signal, may fail to impact the downstream circuitry, or impact it in a marginal way that does not rise above the level of random fluctuation. But two or more neurons firing in synchrony, sending their signals to the same downstream collector, can have a coherent impact that rises above the background noise. Singer and colleagues proposed that the synchronization of neurons was a means of binding together the information carried by those neurons into a single informational unit. When one neuron caries information
A
, and another neuron carries information
B
, and those two neurons are active in synchrony, then information
A
has been linked with or bound to