Giving S knowledge of the stimulus word immediately prior to its exposure increased the probability of S being able to perceive all of the letters of the word (p < .001). While a difference in probability of perception of the letters was found for rare as compared to frequent words (p < .001), this difference completely disappeared when S had prior knowledge of the word. Both of these findings seemed consistent with a response interpretation of word-recognition processes. However, giving S repeated exposures of the word increased the probability of seeing the letters, regardless of whether he had prior knowledge of the word, a result interpreted as quite inconsistent with response processes. Examination of Ss' reports showed that they were perceiving letters, not making guesses about the word, and that the percept of the letters gradually increased in clarity, quite independently of whether they knew the word. (PsycINFO Database Record (c) 2006 APA, all rights reserved)