No description available.

No description available.

No description available.

No description available.

Prominent views in second language acquisition suggest that the age of L2 learning is inversely correlated with native-like pronunciation (Scovel, 1988; Birdsong, 1999). The relationship has been defined in terms of the Critical Period Hypothesis, whereby various aspects of neural cognition simultaneously occur near the onset of puberty, thus inhibiting L2 phonological acquisition. The current study tests this claim of a chronological decline in pronunciation aptitude through the examination of a key trait of American English – reduced vowels, or “schwas.” Groups of monolingual, early bilingual, and late bilingual participants were directly compared across a variety of environments phonologically conditioned for vowel reduction. Results indicate that late bilinguals have greater degrees of difficulty in producing schwas, as expected. Results further suggest that the degree of differentiation between schwa is larger than previously identified and that these subtle differences may likely be a contributive factor to the perception of a foreign accent in bilingual speakers.

No description available.

Studies of speech production and its control have traditionally focused on acoustic parameters and/or articulatory configurations of the end result of the production process as the target of speech production. The representations of production target, however, are far richer than the stereotypical acoustic/articulatory features that have been identified from those traditional studies. Speech production is a process through which mental representations of a language are transformed into vocal tract movements and sounds as physical entities. Thus, the speech production target includes these complete representations, and in order to fully understand how the target is controlled, we need to perturb the production process. This paradigm allows us to see how the production system as a whole corrects behavior in response to the perturbation. By systematically introducing perturbation, it is possible to examine what is needed for the system to detect an error, and how such an error is reduced. This, in turn, enables us to have a better understanding of what the speech production target is and how it is defined. A series of experiments were carried out to examine this issue in this thesis, using a real-time auditory perturbation paradigm. This paradigm perturbs the auditory feedback speakers receive while they are producing a speech segment. In response to the perturbation, subjects spontaneously change their articulation to compensate. The results showed that 1) the speech production target is not a list of independently controlled acoustic features but is a multi-dimensionally defined category that is language dependent 2) spectral and temporal aspects of speech motor control show the same results 3) similar compensation behavior is observed even with using an unfamiliar tool to produce a vowel-like sounds, and 4) an intention to produce a speech category may be manifested in ways that are different than behavior in other motor control studies such as reaching. / Thesis (Ph.D, Psychology) -- Queen's University, 2013-09-30 22:44:48.165

Four speech production experiments were conducted to examine how adults produce preverbal messages involving comparisons. It was argued that the generation of any message involving a comparison involves three decisions. First, a dimension for the comparison must be selected. Second, a contrasting object for this dimension must be selected. Third, a referent must be selected for the contrasting object. Participants were shown three objects on a computer screen and were asked to compare two objects along the dimensions of size (Experiments 1 and 2) or hue (Experiments 3 and 4). For example, a participant might be asked to compare the size of a medium-sized snake to either a small fish or a large bird. With each comparison, participants produced a noun (fish, bird) and an adjective (bigger, smaller) that could be repeated or switched from one trial to another. Experiment 1 showed a large tendency to repeat nouns, suggesting that speakers were repeating referents. Experiment 2, however, showed a large tendency to repeat comparisons to objects of the same size, suggesting that speakers were repeating contrasting objects not referents. Experiments 3 and 4 showed that the repetition effect disappeared after one filler trial. This suggested that decisions were made in short-term working memory. It was concluded that these three decisions are both necessary and sufficient for the generation of a preverbal message involving any comparison.

No description available.

Traditionally, psychologists and linguists have assumed that phonological speech errors result from the substitution of well-formed segments. However, there is growing evidence from acoustic and articulatory analyses of these errors which suggests ac- tivation from competing phonological representations can cascade to articulation. This thesis assumes a cascading model, and investigates further constraints for psy- cholinguistic models of speech production. Two major questions are addressed: whether such a cascading model should include feedback; and whether phonologi- cal representations are still required if articulation is not well-formed. In order to investigate these questions a new method is introduced for the analysis of artic- ulatory data, and its application for analysing EPG and ultrasound recordings is demonstrated. A speech error elicitation experiment is presented in which acoustic and elec- tropalatography (EPG) signals were recorded. A transcription analysis of both data sets tentatively supports a feedback account for the lexical bias effect. Cru- cially, however, the EPG data in conjunction with a perceptual experiment highlight that categorising speech errors is problematic for a cascaded view of production. Therefore, the new analysis technique is used for a reanalysis of the EPG data. This allows us to abandon a view in which each utterance is an error or not. We demon- strate that articulation is more similar to a competing phonological representation when the competitor yields a real word. This pattern firmly establishes evidence for feedback in speech production. Two additional experiments investigate whether phonological representations, in addition to lower-level representations (e.g., features), are required to account for ill-formed speech. In two tongue-twister experiments we demonstrate with both EPG and ultrasound, that articulation is most variable when there is one compet- ing feature, but not when there are two competing features. This pattern is best accounted for in a feedback framework in which feature representations feedback to reinforce phonological representations. Analysing articulation using a technique which does not require the categorisation of responses allows us to investigate the consequences of cascading. It demonstrates that a cascading model of speech production requires feedback between levels of representation and that phonemes should still be represented even if articulation is malformed.