Linguistic informativeness and speech production: An investigation of contextual and discourse-pragmatic effects on phonological variation

In this study I investigate the role of predictability in language production. A long-standing observation in language production is that high frequency and highly predictable words tend to become truncated, or shortened (Schuchardt, 1885; Zipf, 1929). As early as Jespersen (1922), this observation has been described in terms of information value: High frequency words have a low information value, and low informativeness encourages speakers to minimize effort when producing them. Despite the growing body of literature that demonstrates that predictability affects the way words are produced during lexical production, the relationship between predictability and production is not fully understood. The goal of this dissertation is to investigate some aspects of why more predictable words are shortened and how predictability affects production. Specifically, I investigate if hearer knowledge is a possible origin of why highly predictable words are reduced. Additionally, I investigate whether predictability plays a role in non-reductive production processes.; In Chapter 2 of this thesis, I investigate why highly predictable words are reduced in speech. An old intuition is that predictable words are shortened because hearers have other sources of information by which to identify the word (Jesperson, 1922). But there is increasing evidence that predictable words are shorter because of speaker internal processes, such as lexical priming or practiced articulatory routines (Bard et al., 2000). I use psycholinguistic experimentation to address whether hearer knowledge affects reduction. The findings reported here demonstrate that reduction is influenced by hearer knowledge. These results indicate that speakers have a model of hearer knowledge and that this model is updated and consulted during articulation.; Chapter 3 turns to the question of how predictability plays a role in production. Previous research has shown that predictability is correlated with the reduction of words in production. I am interested in whether predictability plays any other role in production. Specifically, in Chapter 3, I investigate whether predictability plays a role in non-reductive production processes. In a corpus study of the prosodic characteristics of words, I demonstrate that the predictability of a word, as measured by its frequency, conditional probability given surrounding words, repetition, and its semantic relatedness to the context, has a significant effect on whether the word bears pitch accent. These results indicate that predictability aids in the construction of prosodic phrases during speech production.; In this thesis I demonstrate that more predictable words are reduced because of assumptions speakers have about hearer knowledge. Additionally, I demonstrate that predictability not only affects reduction processes as earlier work has shown, but it also plays an integral role in the construction of prosodic phrases. These results also indicate that pitch accent is at least in part iconic, and that probabilistic information is available during phonological encoding.