Degree Name

Doctor of Philosophy


Department of Psychology


Event-related potentials were used to investigate brain activity during language processing in word-pair paradigms. The issues addressed related particularly to the sensitivity of N400 component to semantic processing, the automaticity of N400 processing and component overlap between the N400 and P3. A better understanding of N400 processing was obtained by considering the role played by other ERP components in the ERP signature. Component processing and identification were investigated using manipulations of experimental design and selected data analysis techniques (principal components analysis and difference waves). These techniques indicated differences in the magnitude of the N400 effect between tasks, demonstrating that the relatedness effect is task-dependent and therefore does reflect an automatic process. It was also shown that the N400 effect occurs independently of processing associated with the P3 component. The findings were interpreted in a variation of the Interactive Activation model proposed by McClelland (1989) to illustrate the flow of activation in each experimental condition.