88Most research on the role of morphology in word recognition has been focused on whether morphemic analysis is involved in visual word identification. We think that the bulk of the evidence indicates that the answer is yes. For example, in isolated word recognition (e.g., Taft, 1988;Taft & Forster, 1975), the frequency of the root of a prefixed or suffixed English word influences lexical decision time (when the frequency of the whole word is controlled). Similarly, in sentence contexts, the frequency of the root of an English prefixed word (Niswander-Klement & Pollatsek, 2006) and the frequencies of both the first and second constituents of a long Finnish compound word influence the gaze duration on the word in sentence context (Hyönä & Pollatsek, 1998;Pollatsek, Hyönä, & Bertram, 2000). Thus, fixation times on disarray are longer than those on disorder (array has a lower frequency than does order), even though the prefixed words themselves are matched on frequency (Niswander-Klement & Pollatsek, 2006). These results thus indicate that morphemic components are influencing the word-identification process.For words with both a prefix and a suffix, however, there is the additional question of the order in which readers attach the affixes to the root morpheme. For example, for unlockable, if one first attaches the prefix to the root morpheme to get the left-branching structure unlock-able, the word means "can be unlocked," whereas, if one first attaches the suffix to get the right-branching structure unlockable, it means "cannot be locked" (see Figure 1).Words of this form (unXable) are unique in English in having two legal structures. In contrast, relockable has only one legal structure: the right-branching relock-able. That is because the prefix re-applies only to verbs, so that re-lockable is an inadmissible structure. In contrast, a word like unsinkable must have the left-branching structure, unsinkable, because one cannot unsink something. However, this still leaves open the question of how people process trimorphemic words. One possibility is that, for structurally unambiguous words like relockable, readers do not Many trimorphemic words are structurally and semantically ambiguous. For example, unlockable can either be un-lockable (cannot be locked) or unlock-able (can be unlocked). Which interpretation is preferred and whether the preceding sentence context affects the initial interpretation is not clear from prior research. The present experiment embedded ambiguous trimorphemic words in sentence contexts, manipulated whether or not preceding context disambiguated the meaning, and examined the pattern of fixation durations on the ambiguous word and the remainder of the text. The results indicated that the unlock-able interpretation was preferred; moreover, preceding context did not exert a significant effect until the eyes had initially exited from the target word.Psychonomic Bulletin & Review 2010, 17 (1), 88-94 doi:10.3758/PBR.17.1.88 A. Pollatsek, pollatsek@psych.umass.edu