The influence of phonological context on the sound errors of a speaker with Wernicke's aphasia

Positional asymmetries in consonant production and intelligibility in dysarthric speech

Consonant production errors are common in dysarthric speech, but not all consonants are affected to the same extent. Currently, only limited knowledge exists regarding whether different positional allophones are affected to varying degrees in dysarthric speech. The aim of this study was to investigate the effect of consonants' position-in-words on consonant production accuracy and their relevance to speech intelligibility. To this end, the percentage of correctly articulated consonants was analyzed with respect to position-in-words, manner of articulation, and speakers' overall intelligibility in dysarthric speech secondary to cerebral palsy. Results revealed that consonants were generally more accurate in initial positions than other positions, and when they were singletons rather than clusters. However, fricatives, a category commonly noted for frequent misarticulations, exhibited no significant positional effects, indicating that fricatives were affected to a similar degree across all word positions. In addition, positional asymmetry manifested to a greater degree as intelligibility decreased. Finally, the strength of the relationship between consonant production accuracy and intelligibility varied depending on positions-in-words, with strong correlations in the medial and final cluster positions but no significant correlation for fricatives in the initial and final singleton positions. The correlation was markedly low for the initial consonants, possibly due to the resistance of initial consonants to production errors. The positional asymmetry found in this study necessitates more research on non-initial consonants and clusters for their potential in improving consonant production and speech intelligibility as a part of dysarthria management.

Is recurrent perseveration a product of deafferented functional systems with otherwise normal post-activation decay rates?

Recent work in neuropsychology, clinical aphasiology and neuropharmacology have presented evidence that the causative substrates of recurrent perseveration in adults with aphasia are more recondite and subject to distinct interpretations than originally thought. This article will discuss and evaluate how various proposals from theory, from the clinic and from drug therapy interact and compete in the search for a cause or causes of recurrent perseveration.

A structural account of phonological paraphasias

The aim of this study is to develop a partial theory of phonological paraphasias which has some cross-syndrome and cross-linguistic validity. It is based on the distinction between content and structural units and emphasizes the role of the latter. The notion of structure holds the key to an understanding of the differences among the following three types of data: slips of the tongue, slips of the pen (defined as errors committed by healthy, competent adults), and paraphasias. A comparison of these three data types reveals that slips of the pen and paraphasias display striking similarities whereas slips of the tongue stand apart. This pattern emerges very clearly in an analysis of nine empirical effects all of which are found to be of a structural nature. On the basis of these results, it is argued that both the written output of normals and the oral output of aphasics are generated under a reduced structural representation (i.e., weak activation of structural nodes). However, the reasons for the diminished sensitivity to structure are not the same in the two modalities. While the impoverished structural representation is a likely consequence of the relatively slow production rate in writing, it may stem from an impaired transmission of activation among structural nodes in aphasia. By contrast, the normal speaking process occurs under the sway of a full-fledged structural representation. Hence, slips of the tongue are highly sensitive to structural effects.