Thesis: Ph. D., Massachusetts Institute of Technology, Department of Brain and Cognitive Sciences, 2015.Cataloged from PDF version of thesis.Includes bibliographical references (pages 133-142).The trained enhancement of working memory and visual attention has both theoretical implications for understanding the architectures of cognition, as well as practical implications for education and clinical treatment. In particular, transfer of training from one task to another may reveal shared psychological processes or neural systems across domains of cognition. In three experiments presented here, participants underwent a month of intensive training on either a complex working memory task or a visual attention task. Although participants made substantial gains on the trained tasks, that training did not yield transfer to untrained tasks measuring fluid intelligence, reading comprehension, or processing speed (Experiment 1). Brain imaging conducted before and after training revealed that increased working memory performance was accompanied by decreases of functional activation within anatomically circumscribed regions of frontal and parietal cortex as well as more wide-spread increases in frontoparietal functional connectivity (Experiment 2). Visual attention training using adaptively adjusted speeds on a multiple object tracking task revealed sizeable gains on the task itself, and those gains enabled the tracking of an increased number of items at a constant speed. This transfer from speed to quantity suggests that a common process underlies tracking speed and tracking capacity in visual attention (Experiment 3).by Todd Wesley Thompson.Ph. D.