Attention-based rehearsal in spatial working memory.

Spatial working memory has previously been dissociated from other working memory systems, but there has been relatively little research on the specific subcomponents of spatial working memory. I propose a specific model of spatial working memory in which covert shifts of spatial selective attention mediate the on-line maintenance of location-specific representations. Three forms of evidence support this model: (1) A review of the literature shows that there is significant correspondence in the neuroanatomical circuits that mediate spatial selective attention and spatial working memory. A variety of evidence converges on the conclusion that a highly-interactive frontal-parietal network plays a key role in both processes. In addition, there is evidence that when subjects selectively attend to a location, enhanced activation is observed in the extrastriate and striate cortex (regions known to mediate early processing of visual information); and this finding is paralleled by the consistent activation of these regions during neuroimaging studies of spatial working memory. (2) Behavioral studies have shown that observers make faster and more accurate responses to stimuli that fall in attended rather than unattended locations. The same enhanced visual processing can also be demonstrated at memorized versus nonmemorized locations (Experiment 1). These reaction time patterns are not attributable to stimulus-driven shifts of attention, or strategic orienting on the part of subjects (Experiment 2). Moreover, Experiment 3 provides converging evidence for these attentional effects by demonstrating that subjects are impaired in their ability to discriminate colors at non-memorized locations. (3) Finally, Experiment 3 shows that when subjects are hindered in their ability to direct selective attention to memorized locations, their ability to accurately remember spatial information is impaired. This result suggests that the observed shifts of spatial selective attention play a direct functional role in the on-line maintenance of spatial information.Ph.D.Cognitive psychologyPsychobiologyPsychologyUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttp://deepblue.lib.umich.edu/bitstream/2027.42/129837/2/9635483.pd