How does orthographic or phonological similarity produce repetition blindness?

University students reported two words, C1 and C2, and an intervening filler word in rapid serial visual presentation (RSVP). The deficit in reporting the second target C2 (repetition blindness, RB) was examined when C1 and C2 were phonologically or orthographically similar. When C1 and C2 were homophones, there was a deficit in the report of both C1 and C2 and confusion between C1 and C2, suggesting a working memory involvement in phonological RB. The deficit was restricted to C2 when C1 and C2 were orthographically similar (Experiments 2 and 3). In Experiment 4, C1 and C2 shared the first three or the last three letters. Participants chose from two 3-letter fragments the one that came from C2. There was a deficit for similar C2s which was exacerbated for beginning matches with beginning probes. We propose that interference by C1 in the orthography-to-phonology conversion for C2 causes orthographic RB.