Electrophysiological studies of visual word perception, lexical organization, and semantic processing: a tutorial review.

Visual word recognition requires the matching of an orthographic unit to its meaning via a phonological unit in the mental lexicon. The nature and the speed of this process are affected by "bottom-up" factors (e.g., the manner in which the phonology is represented by the orthography) and by "top-down" factors (e.g., network connections between related words in the lexicon, and contextual semantic information). Event-related potentials (ERPs) provide a relatively new tool that complements behavioral measures of word recognition. ERP components recorded during word perception tasks have been found to be sensitive to orthographic, phonological, and semantic manipulations. They go beyond behavioral measures by providing continuous information about the activity of the cognitive system from stimulus onset to the occurrence of the response. In addition, ERPs enable the researcher to examine word perception and reading in more natural situations, without time constraints and overt responses. Finally, intra-cranial ERP recording in humans and modern analytical techniques may shed light on the relations between cognitive linguistic processes and brain structures. Collaboration between cognitive psychologists, linguists, and ERP researchers will be necessary to exploit the great potential of these electrophysiological techniques.