1986Prior to the late 1980s, research on the semantic ambiguity of single words had focused on the process of lexical access. Although various researchers favored different forms of access (exhaustive, context-dependent, ordered; see Simpson, 1984, for a review), the common tendency was to treat each occurrence of an ambiguous word as an independent event. A more recent trend in the ambiguity processing literature has been to examine the effect of the repetition of an ambiguous word in situations in which the appropriate meaning of the ambiguous word varies across occurrences. Changing the contextually appropriate meaning of a homograph across trials in a task can result in large decrements in performance, such as when an individual is required to decide if seal is related to walrus after earlier deciding that seal is related to glue. Maintaining the same meaning context generally facilitates performance, for example, deciding that seal is related to walrus shows a benefit if earlier the participant had decided that seal is related to dolphin (for reviews of this literature see Gorfein, 2001a;Simpson & Kang, 1994). Although Simpson and Kang (1994) have argued that in normal discourse, words are often repeated and therefore the long-term effects of processing each occurrence of an ambiguous word need to be understood, surprisingly little theoretical work has addressed the issue.Simpson and Kellas (1989) reported that once a homograph had been used as a prime for a word related to one of its less common meanings (e.g., bank as a prime for river), a target word related to the dominant meaning of the homograph (e.g., bank followed by money) showed a prolonged naming time in comparison with a neutral baseline, even after a lag of 12 intervening trials. Simpson and Kang (1994) concluded that "Processing one meaning of a homograph and responding to that meaning results in the active and specific inhibition of competing meanings" (p. 376, italics added), thus extending the idea of transient suppression of the nonselected meaning of an ambiguous word to a longer term inhibitory process that endures over a period of time. From a theoretical perspective, Simpson and Kang (1994) suggested that the observed decrement is a form of negative priming (see, e.g., Tipper, 1985), but did not present a specific model. The activation-selection model (ASM) of determining the meaning of an ambiguous word is unique in that it is able to account for the long-term effects of meaning selection without an explicit mechanism for suppressing the representation of the nonselected meaning. The model assumes that a meaning is selected when a threshold number of attributes associated with that particular meaning are activated. When a meaning is selected, the ASM assumes that the weights of the attributes that are associated with the chosen meaning are increased. This two-phase process (transient activation followed by long-term weight changes) provides a mechanism by which meaning selection at one time can affect meaning selection at a much late...