Because of its finite computational resources, the human brain must process information selectively in a variety of domains. Although the fundamental need for selective processing is present at each level from perception to action, there are important differences in the computations performed by different cognitive systems and it is therefore likely that substantially different attentional mechanisms are responsible for selective processing at each stage. Cognitive neurosciences techniques are well suited to make this distinction because they allow different attentional mechanisms to be isolated in terms of timing and/or neuroanatomy. The present article describes the use of event related potential (ERP), positron emission tomography (PET), and magnetic resonance imaging (MRI) techniques, in differentiating the action of attentional mechanisms at the level of auditory, visual and somatosensory perceptual systems. Some common neuronal concomitants are delineated, and implications for the study of attentional supression are discussed.
KEYWORDS: attention, perceptual systems, event related potentials, positron emission tomography, magnetic resonance imaging.