A cognitive psychological investigation of the functional organisation of visual-spatial working memory
There is a good deal of information available from both neuropsychology and cognitive psychology to support the contention that visual short term memory is functionally segregable from spatial short term memory, within the context of a working memory approach to cognitive functioning. However, relatively little is understood about the precise functional relationships between these segregated components or about the method in which they operate. One suggestion has been that the spatial system operates sequentially, in line with the idea that its output is mediated by movement of the body, whilst the visual short term memory system operates a more parallel manner, retaining input from the visual array in a more holistic fashion. In the research reported in this dissertation, methods originally used to research short term memory in experimental animals were adapted for use in adult humans. This was done with the aim of firstly clarifying the patterns of segregation of visual - spatial working memory and secondly beginning to understand the functional architecture of those segregated components. A series of experiments were conducted, initially based on Logie and Marchetti's (1991) demonstration of visuo-spatial segregation and later based on developments of the delayed response (DR) short term memory task used in experimental animals. In all of these experiments an interference paradigm was used to investigate segregation, with the assumption that segregation would manifest itself in differential effects of interference. For example, visual interference should impair visual but not spatial memory task performance, and vice versa for spatial interference. The results of these experiments clearly demonstrated segregation or visual and spatial processing. Furthermore they support the idea that spatial memory is a sequential process and visual memory a parallel one. However it was also observed that sequentially and parallelism were not the sole specifications of the two systems: memory for the appearance and location of items was also important.