A unified, self-organizing model of garden path phenomena, center-embedding phenomena, and interference effects

Two phenomena in sentence processing, the difficulty associated with garden path sentences and the difficulty associated with center embeddings, have generally been ascribed to different features of the parsing mechanism. For example, garden path phenomena are claimed to stem from biases (possibly structural, lexical, discourse, etc.) that cause the parser to favor a parse that eventually turns out to be wrong (e.g., Frazier & Rayner, 1982; MacDonald et al., 1994). Center embedding difficulty has been ascribed to the strain of simultaneously holding in memory the states of multiple partially completed constituents (Gibson, 1998). The current proposal follows Vosse & Kempen (2000)'s observation that that both phenomena arise naturally in a system in which perception of words spawns the activation of phrase-tree fragments which interact in a self-organizing fashion to form larger tree structures. This kind of model treats garden path phenomena as a kind of interference effect: in such cases, one fragment gets the jump on another early in a sentence, but later arriving information allows the initially squashed choice to make a comeback bid, the battle for dominance delaying stabilization. Likewise, because the system allows all words in a sentence to interact with one another, a sequence of similar noun phrases (e.g., "the dog the cat the rat...") followed by a sequence of verbs that can combine with any of them ("...chased bit died") leads to considerable interference and often failure of the parse. Moreover, several recent research projects have found evidence for the novel claim of the self-organizing perspective that all words can interact with each other: Van Dyke et al. (2005) found that that the semantic compatibility of a noun in an embedded clause with the verb phrase in the matrix clause affects eye movements (1); Tabor et al. (2004) found that the parser experiences interference from locally coherent structures even if they are incompatible with the already existing primary parse (2).