Current studies are directed at using functional magnetic resonance imaging (FMRI) to understand visual perception and attention in healthy adults. Since far more visual information is imaged on the retina than can be processed, attentional selection mechanisms are necessary to insure that only important information is analyzed. Similarly, selection mechanisms are necessary to insure that we respond to only those stimuli or events which are relevant to our goals. Work in this and other laboratories has shown that attention can powerfully modulate the response to a stimulus throughout visual cortex. FMRI is currently being used to study the visual and extravisual pathways by which advance information concerning different properties of a test object (e.g. its location, motion, color, etc) modulates areas in the visual system. Two different types of neural signals underlie these modulations: 'instruction signals' that insure that selection mechanisms are properly set by the advance information, and attentional modulations that reflect the effects of that set on the sensory activity evoked by subsequent events. Our research takes advantage of the temporal resolution of fMRI to separately image these signals over the whole brain.