Feedback and regularity in the lexicon

Phonologies are characterised by regularity, from the stereotyped phonetic characteristics of allophones to the contextually conditioned alternations between them. Most models of grammar account for regularity by hypothesising that there is only a limited set of symbols for expressing underlying forms, and that an independent grammar algorithm transforms symbol sequences into an output representation. However, this explanation for regularity is called into question by research which suggests that the mental lexicon records rich phonetic detail that directly informs production. Given evidence for biases favouring previously experienced forms at many levels of production and perception, I argue that positive feedback within a richly detailed lexicon can produce regularity over many cycles of production and perception. Using simulation as a tool, I show that under the influence of positive feedback, gradient biases in usage can convert an initially gradient and variable distribution of lexical behaviours into a more categorical and simpler pattern.