The purpose of this study is to understand how the brain allows individuals to keep information "in mind" over brief intervals. During the experiment, participants will be asked to maintain fixation while they attend to and remember different visual stimuli (e.g., the location of a dot on the screen, the color of a circle, the orientation of a line, the speed of a group of moving dots) on a computer monitor. Participants will make decisions about these visual stimuli and indicate their decisions by pressing buttons or making eye movements. Through the use of Transcranial Magnetic Stimulation (TMS) investigators hope to understand the contributions of different anatomical areas while subjects perform this task.