Time, Light and the Nature of Conscious Vision


Speaker: Christopher Tyler
Date: Thursday 29 January 2015 12:30 pm - 1:45 pm
Venue: Senate House, Senate House, WC1E 7HU
See all events at: Senate House
Category:

Room 246

This lecture will take a large-scope view of the field of vision, which has always had a significant place in the history of philosophy. Lucretius in the early days of the Roman empire had a clear view of light as a wavefront, or film, propagating into the eye, a view that continued through Robert Grosseteste in the C13th, and Leonardo da Vinci in the C15th. How far have we come in understand of light as the medium of vision since then? In fact, we have added the magnetic and polarization components, but the basic concept of a wavefront propagating through time and space has remained unchanged into the quantum era. I will propose a new post-Einsteinian view of the nature of both time and light in this context conceptualized as the fractal extrapolation of a 6D space-time kernel.

This leads to the question of the nature of the cortical visual representation of the information carried by light. Is the cortex best regarded as an undifferentiated neural net simply forming arbitrary patterns of activation reflecting the spatiotemporal contingencies of the impinging world? Or is it structured in an organizational arrangement specifically suited to efficient neural processing, or constrained by earlier evolutionary adaptations? The nature of the inhabited world is largely one of three-dimensional objects and structures, in contrast to its two-dimensional projection to the retina. I will consider a Riemannian Uniformization approach to the problem of three-dimensional representation.

My third topic is the nature of the conscious processing of this information. Consciousness is well-recognised ‘hard problem’, but it has some defined properties that allow us to make some headway in analyzing its substrate. Consciousness is i) unitary, ii) private, iii) cyclically switchable, iv) multifaceted, v) operational, vi) complexly interconnected, vii) iterative, viii) autosuppressive (except in obsessive disorders), and ix) individuated to communicative brainholders. These nine properties can help us to narrow down the options for its neuronal substrate. They have some intersection with, but are rather more cogent properties than, the axioms recently proposed by Tononi (2008) and underwritten by Koch (2012), which seem notably flaccid as useful criteria.

Having completed his education in England, Christopher Tyler has spent his research career in the United States exploring the fascinating processes of how the eyes and brain work together to produce meaningful vision. He has developed rapid tests for the diagnosis of diseases of this visual processing in infants and of retinal and optic nerve diseases in adults.. His recent scientific work concerns theoretical, psychophysical and functional MRI studies of the global processes of object perception through motion, symmetry, figure/ground and stereoscopic depth perception. He has discovered many aspects of the neural interactions involved in both static and dynamic 3D perception. In the process, he developed the concept for the ‘Magic Eye’ images for showing 3D scenes in a single image without special glasses, which became very popular in the 1990s and has emphasized the importance of 3D structure in object and face perception in computer science applications.