| This dissertation takes a cognitive approach to the study of language, using speech errors as the primary source of data. It is shown that only an interactive model of language production is capable of explaining all of the available speech error facts. The Interactive Activation model of McClelland and Rumelhart (1981) is extended to provide a model of language production. This model makes correct predictions about the types of errors that will occur during the accessing of words, including the effects of syntax on the selection of words. It is shown that serial order should be represented as a hierarchical avalanche. The model of attention and automatization of Norman and Shallice (1980) is adapted to language to predict what types of units should be listed in the lexicon. Within this framework, I examine whether the morphemes and lower-level units in lexical entries are stored in multiple copies scattered throughout the lexicon and whether such copies must at least contain internal morphological structure, or whether morphemes are accessed as rules, either as major rules on the basis of semantic, pragmatic, and syntactic information, or as minor rules accessed by known lexical items. Evidence from speech errors demonstrates that morphemes are not stored in multiple copies, but are accessed as rules. Productive inflectional and derivational affixes are accessed at least partly as major rules, while nonproductive rules are accessed only as minor rules. All phonological information (segments, features, and syllable structures) is also accessed as minor rules. An essentially autosegmental description of morphological rules is developed. It is shown that rules can combine affixes and base forms without any sort of abstractness by assuming that morphological rules apply at the point in processing where units are being accessed. Lexical items that are related by minor rules essentially have overlapping entries. Different rules also have overlapping entries, with many subrules accessed by several rules. There is no extrinsic ordering of morphological rules; rules are accessed in parallel, with some intrinsic ordering determined solely by the content of the rules. |
