Perceptual organization and its influence upon attention

Abstract

Humans are able to control so much of their environment not through brute strength or enhanced sensory receptors, but through our ability to understand the world around us. In order to make sense of the world around us we need to organize the information that our sensory systems receive. One of the most fundamental steps in this organizational process lies in the construction of objects. By breaking down our sensory input into objects the mind provides a basis upon which it can begin to scaffold our understanding of the world.
This thesis therefore explores the basic stages at which the visual system organizes our sensory input into distinct objects. It explores these stages by exploiting the fact that the brain’s limited processing resources can be selectively allocated on the basis of ‘object-hood’. This allocation of processing resources, or attention, on the basis of these early stages of segmentation is commonly referred to as ‘object based attention’. ‘Object based attention’ and perceptual organisation are explored in three sections in this thesis:

Understanding the Phenomenon of Object Based Attention.
The first three chapters of this thesis seeks to further our understanding of the phenomenon of ‘object based attention’, for example, chapter 3 explores whether the visual system can simultaneously parse several objects as potential units of attention, or whether it can only segment one or two objects at a time.

Object Based Attention, a Tool to Explore the Nature of Perceptual Organisation
The second section of this thesis attempts to use the phenomenon of ‘object based attention’ as a tool to explore the nature of perceptual representations, for example chapter 5 tests whether different modalities (in particular vision and touch) are able to directly share information about objects in order to build up an integrated model of the external world.

Object Based Attention, Perceptual Organisation and Shape Processing Area LO.
In the final section of this thesis the nature of perceptual organization is explored in a patient with a very specific form of brain damage that enables us to ask what areas of the brain are critically required for different aspects of perceptual organization.