Event-related potentials and the phonological processing of words and non-words.

Event-related potentials (ERPs) were recorded during a task which required subjects to discriminate between rhyming and non-rhyming visually presented pairs of letter strings, consisting of equal proportions of word-word and word-non-word combinations. Pair members were presented sequentially with an interstimulus interval of 1.56 sec. As in a previous study [Rugg, M. D., Brain Lang. In press], ERPs elicited by rhyming and non-rhyming words were differentiated by a late negative component (N450) in waveforms following the non-rhyming words. This effect was greatest over the midline and the right hemisphere. The same rhyme/non-rhyme difference was also observed, to an equal extent, in ERPs elicited by non-words. It is concluded that N450, presumed to be related to the "N400" component observed under conditions of semantic incongruity [Kutas, M. and Hillyard, S.A., Science 207, 203-205, 1980] does not seem to depend on linguistic processing at the semantic level for its modulation.