"The proposed project will investigate how selective attention is implemented in the architecture of the visual system. Using both behavioral and cognitive neuroscience methods, we will study attentional tracking of multiple objects that move independently in the visual field. Previous research has shown that the capacity to select and monitor multiple objects and their locations varies as a function of visual field: twice as many objects can be selectively tracked when presented bilaterally (i.e., in both left and right hemifields) compared to when they are presented unilaterally (i.e., within a single hemifield). These behavioral findings imply considerable independence of the attentional resources for each visual field, thereby challenging the traditional view of attention as a central, monolithic resource. We hypothesize that attentional tracking of independently moving objects is subserved by hemifield-specific attentional foci that (i) alter the suppressive profile of attention independently for each hemifield, and that (ii) these attentional foci are implemented in a dynamic parietal network that changes configuration depending on how attention is allocated in the visual field. Several experiments will be conducted using scalp recorded steady-state visual evoked potentials (SSVEP), functional magnetic resonance imaging (fMRI), and behavioral responses in healthy adults with the goal of constructing a complete framework that explains attentional tracking and the mechanisms of multifocal attention. The project will significantly contribute to our understanding of basic attention and perception mechanisms and will also improve our understanding of human performance in many everyday situations that require us to pay attention to multiple items at the same time."