DESCRIPTION (Investigator's Abstract): The global aim of the research outlined in this proposal is to expand the investigators knowledge of the psychological and physiological bases of meaning. The primary approach will involve the recording of event-related potentials (ERPs) to linguistic and pictorial stimuli from scalp electrodes in normal intact human subjects. Current evidence suggests that the N400 component of the ERP is an electrophysiological index of some aspect of word processing (possibly word recognition) which reflects the influence of semantic context at both the lexical and sentential levels. The proposed experiments are designed to further examine these hypotheses and to then use these components to address specific questions about the cognitive processes involved in comprehension. Specifically the first four experiments focus on the degree to which sentence level semantics, pragmatics and syntax dominate or can alter the processing of purely lexical relationships. Experiments five through nine are designed to determine the extent to which pragmatic and lexical factors influence the processing of whether the nature or time course of the meaning derived from a written word differs from that derived from a picture. The goal here is to allow inferences about amodal versus linguistic representations of meaning.