AN INFORMATION INTEGRATION
THEORY OF CONSCIOUSNESS

GIULIO TONONI

Department of Psychiatry, University of Wisconsin

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AN INFORMATION INTEGRATION THEORY OF CONSCIOUSNESS

GIULIO TONONI

Department of Psychiatry, University of Wisconsin,
Madison, USA Email:
Giulio Tononi* - gtononi@wisc.edu

An Information Integration Theory of Consciousness

Giulio Tononi

This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons. org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Background

Consciousness poses two main problems. The first is understanding the conditions that determine to what extent a system has conscious experience. For instance, why is our consciousness generated by certain parts of our brain, such as the thalamocortical system, and not by other parts, such as the cerebellum? And why are we conscious during wakefulness and much less so during dreamless sleep? The second problem is understanding the conditions that determine what kind of consciousness a system has. For example, why do specific parts of the brain contribute specific qualities to our conscious experience, such as vision and audition?

Presentation of the hypothesis

This paper presents a theory about what consciousness is and how it can be measured. According to the theory, consciousness corresponds to the capacity of a system to integrate information. This claim is motivated by two key phenomenological properties of consciousness: differentiation - the availability of a very large number of conscious experiences; and integration - the unity of each such experience. The theory states that the quantity of consciousness available to a system can be measured as the ? value of a complex of elements. ? is the amount of causally effective information that can be integrated across the informational weakest link of a subset of elements. A complex is a subset of elements with ?0 that is not part of a subset of higher ?. The theory also claims that the quality of consciousness is determined by the informational relationships among the elements of a complex, which are specified by the values of effective information among them. Finally, each particular conscious experience is specified by the value, at any given time, of the variables mediating informational interactions among the elements of a complex.

Testing the hypothesis

The information integration theory accounts, in a principled manner, for several neurobiological observations concerning consciousness. As shown here, these include the association of consciousness with certain neural systems rather than with others; the fact that neural processes underlying consciousness can influence or be influenced by neural processes that remain unconscious; the reduction of consciousness during dreamless sleep and generalized seizures; and the time requirements on neural interactions that support consciousness.

Implications of the hypothesis

The theory entails that consciousness is a fundamental quantity, that it is graded, that it is present in infants and animals, and that it should be possible to build conscious artifacts.

Background

Consciousness is everything we experience. Think of it as what abandons us every night when we fall into dreamless sleep and returns the next morning when we wake up [1]. Without consciousness, as far as we are concerned, there would be neither an external world nor our own selves: there would be nothing at all. To understand consciousness, two main problems need to be addressed. [2,3]. Thefirst problem is to understand the conditions that determine to what extent a system has consciousness. For example, why is it that certain parts of the brain are important for conscious experience, whereas others, equally rich in neurons and connections, are not? And why are we conscious during wakefulness or dreaming sleep, but much less so during dreamless sleep, even if the brain remains highly active? The second problem is to understand the conditions that determine what kind of consciousness a system has. For example, what determines the specific and seemingly irreducible quality of the different modalities (e. g. vision, audition, pain), submodalities (e. g. visual color and motion), and dimensions (e. g. blue and red) that characterize our conscious experience? Why do colors look the way they do, and different from the way music sounds, or pain feels? Solving the first problem means that we would know to what extent a physical system can generate consciousness - the quantity or level of consciousness. Solving the second problem means that we would know what kind of consciousness it generates - the quality or content of consciousness.

                                                         PRESENTATION OF THE HYPOTHESIS

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AN INFORMATION INTEGRATION
THEORY OF CONSCIOUSNESS

GIULIO TONONI







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