The Nature of Consciousness

Piero Scaruffi

(Copyright © 2013 Piero Scaruffi | Legal restrictions )
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These are excerpts and elaborations from my book "The Nature of Consciousness"

Dimensions of Cognition

The obvious criticism against production systems is that they don't "look like" our brain.

David Marr claimed that a scientist can choose either of three levels of analysis: the computational level (which mathematical function the system must compute, i.e. an account of human competence), the algorithmic level (which algorithm must be used, i.e. an account of human performance) or the physical level (which mechanism must implement the algorithm). Different sciences correspond to different levels: Cognitive Science studies the mind at the computational level, Neurology studies the mind at the physical level, Eye Medicine studies the mind at the algorithmic level.

Newell refined that vision by dividing cognition into several levels.  The program level represents and manipulates the world in the form of symbols. The knowledge level is built on top of the symbolic level and is the level of rational agents: an agent is defined by a body of knowledge, and has some goals to achieve and some actions that it can perform. An agent's behavior is determined by the "principle of rationality": the agent performs those actions that, on the basis of the knowledge it has, will bring it closer to the goals. General intelligent behavior requires symbol-level systems and knowledge-level systems. 

Newell then broadened his division of cognitive levels by including physical and biological states.

The whole band can be divided into four bands: neural, cognitive, rational and social.

The cognitive band can be divided based on response times: at the memory level, the response time (the time required to retrieve the referent of a symbol) is about 10 milliseconds; at the decision level the response time is 100 milliseconds (the time required to manipulate knowledge), at the compositional level it is one second (time required to build actions), at the execution level it is 10 seconds (time required to perform the action). 

At the rational band the system appears as a goal-driven organism, capable of processing knowledge and of exhibiting adaptive behavior.


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