Steven Allen Hillyard

Distinguished Professor of Neurosciences. Pioneer in analyzing the neural mechanisms of attention, perception, and cognition. Research combined electrophysiological and neuromagnetic recordings of brain activity with hemodynamic neuroimaging to reveal the spatio-temporal organization of attentional selection, perceptual integration, cross-modal interaction and semantic memory processes in the human brain. His studies were first to show that both auditory and visual selective attention in humans involves a mechanism of sensory gain control or amplification of attended inputs at an early stage of processing in modality-specific cortex. His group identified the timing and cortical localization of feature-selective and object-selective attention processes and multisensory integration mechanisms. They discovered that frequency-tagged oscillatory potentials elicited in the visual cortex could be utilized to reveal the allocation of attention within large stimulus arrays and thereby elucidate mechanisms of visual search and attention switching. He contributed to research in language and memory with the codiscovery of the N400 effect, a negative brain potential elicited when the semantic content of a word or event is unexpected in the ongoing context.