Neural Computations Underlying Phenomenal Consciousness: A Higher Order Syntactic Thought Theory.

Edmund T Rolls

doi:10.3389/fpsyg.2020.00655

Abstract

Problems are raised with the global workspace hypothesis of consciousness, for example about exactly how global the workspace needs to be for consciousness to suddenly be present. Problems are also raised with Carruthers’s (2019) version that excludes conceptual (categorical or discrete) representations, and in which phenomenal consciousness can be reduced to physical processes, with instead a different levels of explanation approach to the relation between the brain and the mind advocated. A different theory of phenomenal consciousness is described, in which there is a particular computational system involved in which Higher Order Syntactic Thoughts are used to perform credit assignment on first order thoughts of multiple step plans to correct them by manipulating symbols in a syntactic type of working memory. This provides a good evolutionary reason for the evolution of this kind of computational module, with which, it is proposed, phenomenal consciousness is associated. Some advantages of this HOST approach to phenomenal consciousness are then described with reference not only to the global workspace approach, but also to Higher Order Thought (HOT) theories. It is hypothesized that the HOST system which requires the ability to manipulate first order symbols in working memory might utilize parts of the prefrontal cortex implicated in working memory, and especially the left inferior frontal gyrus, which is involved in language and probably syntactical processing. Overall, the approach advocated is to identify the computations that are linked to consciousness, and to analyze the neural bases of those computations.

Highlights

A theory of phenomenal consciousness has recently been described that holds that this arises when there is a global workspace with non-conceptual content (Carruthers, 2019)
Problems have been raised with the global workspace hypotheses of consciousness, for example about exactly how global the workspace needs to be for consciousness to suddenly be present, and that the hypothesis deals mainly with access consciousness (Dehaene, 2014)
Problems have been raised with a version (Carruthers, 2019) that excludes conceptual representations, and in which phenomenal consciousness can be reduced to physical processes

Summary

INTRODUCTION

A theory of phenomenal consciousness has recently been described that holds that this arises when there is a global workspace with non-conceptual content (Carruthers, 2019). Part of my HOST theory of consciousness (see Section “A Computational Hypothesis of Phenomenal Consciousness” onwards) is that it provides a computational reason why the threshold for information to reach consciousness is higher than the threshold for information to influence behavior in what is referred to as subliminal processing (Dehaene et al, 2006) Another example is much of the sensory processing and actions that involve the dorsal stream of visual processing to the parietal cortex, such as posting a letter through a letter box at the correct orientation even when one may not be aware of what the object is (Milner and Goodale, 1995; Milner, 2008; Goodale, 2014). Reasoning typically may involve multiple steps of ‘if... ’ conditional statements, all executed as a one-off or one-time process (see below), and is very different from associatively learned conditional rules typically learned over many trials, such as ‘if yellow, a left choice is associated with reward.’

A Computational Hypothesis of Phenomenal Consciousness

CONCLUSION