Participants' eye movements were monitored while they read sentences in which high-and lowfrequency target words were presented normally (i.e., the normal condition) or with either reduced stimulus quality (i.e., the faint condition) or alternating lower-and uppercase letters (i.e., the case-alternated condition). Both the stimulus quality and case alternation manipulations interacted with word frequency for the gaze duration measure, such that the magnitude of word frequency effects was increased relative to the normal condition. However, stimulus quality (but not case alternation) interacted with word frequency for the early fixation time measures (i.e., first fixation, single fixation), whereas case alternation (but not stimulus quality) interacted with word frequency for the later fixation time measures (i.e., total time, go-past time). We interpret this pattern of results as evidence that stimulus quality influences an earlier stage of lexical processing than does case alternation, and we discuss the implications of our results for models of eye movement control during reading.Keywords Reading . Eye movements . Case alternation . Stimulus quality . Lexical processing . Word frequency Over the past three decades, the study of eye movement control during reading has been the focus of extensive empirical and theoretical efforts (for reviews, see Rayner, 1998Rayner, , 2009 Feng, 2006). These models incorporate various assumptions and generate unique predictions that have inspired empirical tests.Of particular relevance to the present study, Reingold and Rayner (2006) tested the central assumption of the influential E-Z Reader model (Reichle, 2011;Reichle et al., 1998;Reichle, Pollatsek, & Rayner, 2012) that word identification reflects two separate stages of lexical processing. Specifically, the E-Z Reader model assumes that the initiation of the programming of a saccade to the next word (word n + 1 ) occurs prior to the completion of lexical access to the fixated word (word n ). Saccadic programming is postulated to be driven by the output of an early lexicalprocessing stage (L 1 ), which indicates that lexical access to word n is imminent. Lexical processing of word n is then completed during a subsequent stage of lexical processing (L 2 ), and the conclusion of this stage causes covert attention to shift to word n + 1 . During the interval of time between this attention shift and the launch of the word n -to-word n + 1 saccade, parafoveal processing of word n + 1 is initiated. The duration of this interval, referred to as the parafoveal preview, is expected to determine the magnitude of any processing benefit when word n + 1 is later fixated (with longer preview resulting in shorter fixations on word n + 1 ). Importantly, as was argued by Reingold (2003), the E-Z Reader model predicts that experimental manipulations that disrupt L 1 but not L 2 should influence the processing difficulty of word n without affecting the processing of word n + 1 , whereas manipulations that impact L 2 should impact wor...