Automatic word form processing in masked priming: an ERP study

Five prime types (unrelated words, pronounceable nonwords, illegal strings of letters, false fonts, or neutral strings of Xs) preceded word and nonword targets in a masked priming study designed to investigate word form processing as indexed by event-related potentials (ERPs). Participants performed a lexical decision task on targets. In the 150-250-ms epoch at fronto-central, central, and temporo-parietal sites ERPs were smallest to targets preceded by words and nonwords, followed by letter strings, false fonts, and finally neutral primes. This refractory pattern sensitive to orthography supports the view that ERPs in the 150-250-ms epoch index activation of neural systems involved in word form processing and suggests that such activation may be graded, being maximal with word-like stimuli and relatively reduced with alphabet-like stimuli. Further, these results from a masked priming paradigm confirm the automatic nature of word form processing.