A theory of consciousness from a theoretical computer science perspective: Insights from the Conscious Turing Machine (CTM)

Professors Lenore and Manuel Blum

The quest to understand consciousness, once the purview of philosophers and theologians, is now actively pursued by scientists of many stripes. This paper studies consciousness from the perspective of Theoretical Computer Science (TCS), a branch of mathematics concerned with understanding the underlying principles of computation and complexity.

This research demonstrates how a TCS perspective and insights can contribute to the understanding of consciousness and related concepts, such as free will. In the spirit of TCS, a simple formal mathematical model, the Conscious Turing Machine (CTM), is defined. The approach melds Theoretical Computer Science with Cognitive Neuroscience and shows some of its potential.   

The CTM is inspired by Alan Turing’s model of computation, the Turing Machine (TM), and by the Global Workspace Theory (GWTof consciousness, originated by cognitive neuroscientist Bernard Baars and further developed by Baars, Stanislas Dehaene, Jean-Pierre Changeux, and others.  

This current research by professors Lenore Blum and Manuel Blum, published May 20, 2022 in PNAS online, carries forward ideas with deep roots at Carnegie Mellon, including pioneering work by Allen Newell, Herb Simon, and Raj Reddy. In the preface to The Theater of Consciousness: The Workspace of the Mind, Baars notes that GWT “derives from the integrative modeling tradition of [Allan] Newell, Herbert A. Simon, John Anderson, and others in cognitive science.” 

Phenomena generally associated with consciousness, such as blindsight, inattentional blindness, change blindness, dream creation, and free will, are considered. Explanations derived from the model draw confirmation from consistencies at a high level, well above the level of neurons, with the cognitive neuroscience literature.

The TM is a simple model to define and explore computation. CTM follows as a simple model to define and explore consciousness and related concepts. The CTM is not a model of the brain or cognition. It is intentionally too simple for that, being a purposely simple substrate-independent computational model of the complex concept of consciousness. 

Graphic representing the Conscious Turing Machine (CTM) computational model: long description available

The full text paper is available via PNAS: https://www.pnas.org/doi/full/10.1073/pnas.2115934119

A formatted pdf version is also available via PNAS: https://www.pnas.org/doi/epdf/10.1073/pnas.2115934119

For More Information, Contact:

Jenn Landefeld - csd-marcom-info@cs.cmu.edu