In speech convergence, people's speech becomes more like the speech they hear. Such convergence behavior has been observed along many domains of linguistic structure and in many different situational contexts. Convergence has been argued to be socially motivated (Communication Accommodation Theory — Giles et al. 1991), and also to be an unconscious, resource-free process (Interactive Alignment Theory — Pickering & Garrod 2004). This dissertation presents an alternative approach in which convergence is not a discrete process in itself; rather, convergence behavior is the consequence of episodic storage and recall, moderated by attention.

The first chapter of this dissertation consists of an elaboration of this approach, called the categorization schema account. In this approach, episodic storage is constrained by the categorization schemata that are currently active, and categories are only active when attention is paid to those categories' defining features. Convergence across disparate domains of linguistic structure is then an empirical pattern that falls out naturally from the assumption that multiple representations of the same input are stored separately and recalled independently. In consequence, speakers may converge to different domains of linguistic structure at different rates, depending on which domains have their attention.

The two subsequent chapters report the results of a pair of studies designed to examine predictions made by the categorization schema account. A Mechanical Turk experiment, discussed in Chapter 2, failed to find a significant difference between convergence to words and convergence to pseudowords. In a dyadic game task experiment comparing convergence rates across levels of linguistic structure, discussed in Chapter 3, participants exhibited different patterns of convergence to phonetic features on the one hand, and to lexical and syntactic features on the other hand. Additionally, participants who self-reported a greater degree of personal autonomy in this experiment exhibited less convergence behavior across domains.

Chapter 4 discusses the ramifications of these findings for theories of sound change, and reports the results of an experiment illustrating that accommodation can directly result in the appearance of new variants within an interaction, providing a possible pathway for the actuation of sound change.