Examining the representation of spatial short-term memories through the lens of resource allocation theory

Abstract

This thesis aims to examine the nature of spatial representations in visuospatial working memory (VSWM) and the mechanism by which the oculomotor system supports VSWM maintenance. To examine these research questions, Chapter Two verifies the use of a continuous report task in measuring memory for spatial locations, showing that the representation of spatial locations is affected by the number of to-be-remembered items. In Chapter Three, a strong eccentricity effect in spatial, but not colour, working memory was observed. This result is argued to reflect that the resource involved in spatial working memory relies on topographic mapping. Chapter Four examined the distribution of resources across sequences of spatial locations. Results showed that the serial position effect, and therefore the distribution of resources, depends on whether the full sequence or a single probe is to be recalled. To examine the role of the oculomotor system, saccadic interference in spatial and colour working memory was examined in Chapter Five. Results showed that the oculomotor system is selectively involved in maintenance of spatial locations in VSWM. Performing multiple delay-period saccades resulted in an increase in guessing, but not imprecision, in spatial working memory. It is argued that spatial locations in VSWM are represented as activity peaks in a topographic cortical map. Within this map, the oculomotor system is involved in maintaining the signal to noise ratio of activity peaks for each of the to-be-remembered locations. This research makes an important and novel contribution to the literature by advancing understanding of the nature of representations within spatial working memory and interactions between VSWM and action systems.