Phonology in Prader-Willi syndrome: an optimality theory account

Abstract

This dissertation studies the consonantal phonology of children and young people with Prader-Willi Syndrome (PWS), within the framework of Optimality Theory (OT). PWS is a chromosomal disorder that is caused by the deletion or partial deletion of chromosome 15. Typical characteristics include hypotonia at birth, obesity due to insatiable hunger, short stature and some degree of cognitive dysfunction. It is estimated that PWS occurs in around 1 in 10,000 births. Data on the phonological characteristics found in PWS are limited as little is known about this very rare syndrome. Typical linguistic features of PWS are delayed acquisition of the phoneme system (Dyson and Lombardino, 1989), a high error rate with coronals and dorsals (Kleppe, Katayama, Shipley and Foushee, 1990), devoicing and cluster reduction (Defloor, 2002). These findings, however, do not provide a full picture of the phonology of persons with PWS and the various errors that can occur.

As research regarding phonology in PWS is limited, the aim of this investigation is to provide an in depth analysis of the patterns that occur in the disordered speech of participants with PWS. The framework of Optimality Theory (Prince and Smolensky,1993) will be used not only to gain a deeper understanding of the constraints which the participants adhere to but to also demonstrate that Optimality Theory can be used effectively to account for the patterns observed in disordered speech.

Following on from a pilot study of one participant, eight participants are used for the main study. Here both spontaneous and non-spontaneous speech is used. This not only allows for comparisons to be made, it provides a greater quantity of data. The data are analysed for both onsets and codas. This includes simple and complex consonant structures.

In both onset and coda segments are either substituted or deleted. For consonant clusters, the cluster is reduced to a single segment and this also occurs in both onset and coda position. Furthermore it is found that the participants adhere to sonority in that onset clusters are reduced to the least sonorous member whilst coda clusters are reduced to the most sonorous member. Findings are accounted for by the re-ranking of constraints where the participants violate faithfulness constraints to avoid violations of markedness constraints.

The findings from this study go towards an understanding of the phonological characteristics present in PWS. They also provide evidence that disordered phonology can be effectively described through the use of OT.

Date of Award	Dec 2010
Original language	English
Supervisor	Raffaella Folli (Supervisor)