The foreign accent syndrome: A perspective

Abstract

Although there are now a fair number of reported case studies of the foreign accent syndrome, there is little consensus about it. We provide a perspective on the foreign accent syndrome focusing on three areas for which there is as yet disagreement in the literature. These include whether the foreign accent syndrome is indeed a syndrome in its own right, whether the features of the disorder can be explicated in terms of a single underlying mechanism, and whether there is a common neural substrate that gives rise to this disorder. Based on a review of the literature and our own work, we propose that the foreign accent syndrome is properly considered a syndrome and that it is distinct in both its characteristics and underlying mechanism from an apraxia of speech, a dysarthria, and an aphasic speech output disorder. We hypothesize that a deficit in linguistic prosody underlies the foreign accent syndrome. And finally, we argue that the foreign accent syndrome emerges as a consequence of damage to the dominant language (usually left hemisphere) speech output motor system affecting the primary motor cortex and either its cortico-cortical connections or its cortico-subcortical projections.

Introduction

The foreign accent syndrome has been of great interest in the neurolinguistic and neuropsychological literature as well as in the popular press in part because of the very unique features it displays and in part because of the challenge it provides for our understanding of the neural systems underlying speech production. While there are now a fair number of reported cases, there is still little consensus about this syndrome. There is disagreement about whether the foreign accent syndrome is indeed a syndrome in its own right or a subtype of an apraxia, aphasia, or dysarthria. There is disagreement about whether the features of the disorder can be explicated in terms of a single underlying mechanism. And there is disagreement about whether there is a common neural substrate that gives rise to this disorder. In the following, we consider each of these issues in an attempt to provide a perspective on the foreign accent syndrome.

The proposals that we will outline concerning the basis of the foreign accent syndrome, its underlying mechanism, and its neuropathology are just that, hypotheses which will need further study. One of the factors which has contributed to the difficulty of determining the nature of the foreign accent syndrome has been the very different approaches that have been taken in the analyses of the individual case studies. Some studies have focused on descriptive assessments of listeners, others have focused on analysis of broad and/or narrow phonetic transcriptions, and still others have used instrumental analyses to quantitatively assess the speech patterns of the patients. The stimulus materials have varied widely across studies, making direct comparisons across subjects difficult. The focus of these studies has also been different. Some have tried to determine whether the features of their patient's output matched a particular foreign accent or dialect, and others compared the productions to the patient's native language. And finally, the range of different native languages of the patients studied has varied considerably, making it difficult to assess whether different patterns across studies reflect the impairment of different mechanisms across patients or the different phonetic-phonological structures of the languages studied. Nonetheless, the studies of the foreign accent syndrome to date have provided a rich set of data which are beginning to show some important commonalities that we believe allow for some general hypotheses about the nature of the syndrome, its basis, and its neural underpinnings.