Artefactual Structure from Topographic Mappings

Abstract

This thesis is a study of the problem of artefactual structure from topographic mappings, in
particular Sammon’s Mapping and its close relative Metric Multidimensional Scaling. Such
structure is termed artefactual because it is not representative of true underlying structure in the data and is a side-effect of the mapping algorithm. The problem is investigated from both an experimental and a theoretical standpoint, and it is found that the choice of distance metric in the mapping algorithm is fundamental to the degree of artefactual structure observed.

The results of this work are then used to gain insight into a recent and controversial use of techniques from Multidimensional Scaling in the analysis of the connectivity of regions in the macaque monkey visual cortex. In particular it has been debated in the academic
literature the extent to which the resulting mappings are corrupted by artefactual structure. This premise is investigated experimentally and the support of the mappings for the “two
streams” hypothesis of visual processing is discussed in detail.

Date of Award	Sept 1999
Original language	English
Awarding Institution	Aston University