Electrophysiological studies of the time-course of visual word processing

The human visual system is able to discriminate, categorize and recognize stimuli from a surprisingly large set of potential items in something less than a second. For the past several years we have been using an adaptation of the masked priming paradigm pioneered by Forster and colleagues in combination with the recording of event-related potentials (ERPs). The focus of this work has been on providing a better understanding of the temporal dynamics of the rapid set of processes that are thought to underlie visual word recognition. While behavioral and functional imaging work have been informative about the processing nature and anatomical locus of neural systems involved in visual recognition, because of limitations in their temporal resolution neither of these approaches is well suited to untangling the time-course of the various processes underlying recognition. Because they offer continuous measures of sensory, perceptual and cognitive processes from stimulus onset until hundreds of milliseconds later, ERPs would seem to be ideally suited to providing a clearer picture. In my talk I will present data from a number of studies we have conducted using the ERP mask priming paradigm. In particular I will discuss data from experiments that have revealed a set of ERP effects starting as early as 100 ms and extending to 500 ms that we propose are sensitive to the cascade of operations underlying visual word processing.