The influence of plural dominance in aphasic word production

Abstract

Background: Plural dominance refers to the relative difference between the frequencies of a word in its singular and plural forms. Most of the evidence for theoretical accounts of plural dominance has come from psycholinguistic perception experiments (e.g., Baayen, Burani, & Schreuder, 1996; Baayen, Dijkstra, & Schreuder, 1997; Baayen, Schreuder, & Sproat, 1998). Only a few studies have investigated the production side of dominance, even in unimpaired speakers (e.g., Baayen, Levelt, Schreuder, & Ernestus, 2008). To our knowledge there is only one published neuropsychological study from Luzzatti, Mondini, and Semenza (2001) that uses reading-aloud data from an Italian brain-impaired speaker. Although findings across paradigms are inconsistent, they do indicate that plural-dominant nouns behave differently from singular-dominant nouns, and therefore suggest a difference in representation.

Aims: This paper investigates processing of plural nouns in aphasia with a specific focus on effects of dominance.

Methods & Procedures: We carried out two single-case studies with two women with aphasia, FME and DRS, who showed word retrieval deficits in picture naming as a result of different underlying functional impairments. The main task of interest was picture naming of single and multiple objects in order to test effects of plural dominance. In addition, word–picture matching tested number representation in comprehension.

Outcome & Results: DRS showed a specific morphological impairment with plural marking, whereas FME had no specific morphological deficit. The results are discussed in the framework of current psycholinguistic accounts on the representation and processing of plural nouns (e.g., Levelt, Roelofs, & Meyer, 1999; Schreuder & Baayen, 1995).

Conclusions: Different effects of plural dominance shown by both women with aphasia result from different underlying functional deficits, which indicate differences in the representation of plural dominance across processing levels.

Keywords:

• Picture naming in aphasia
• Language production
• Plural representations
• Plural dominance effect
• Full listing
• Decomposition

Acknowledgments

We are very grateful to FME and DRS for their cooperation, and the time and motivation they contributed to this study. Thank you to Nora Fieder, Catherine Mason, David Howard, and Marcus Taft for helpful discussions and comments. Thanks to Steven Saunders who helped with the extraction of words from CELEX.

This paper was prepared while Britta Biedermann was a Macquarie University Research Fellow (MQRF) and an Australian Research Council (ARC) Postdoctoral Fellow, Antje Lorenz was a post-doctoral research fellow at the Department of Psychology, University of Muenster. Lyndsey Nickels was a National Health and Medical Research Council (NHMRC) Senior Research Fellow, and Elisabeth Beyersmann was supported by a Macquarie University Research Scholarship MQRES.

Notes

¹Decomposition and full parsing are used synonymously in the literature, but as parsing refers predominantly to an input process, whereas decomposition can apply to both input and output we use this term in the remainder of this paper.

²Although we are reporting the combined scores, separate analyses of the initial and the repeat testing sessions revealed the same pattern of results as the combined analyses.

³Here all number errors were included, even if stem was incorrect. Note that in subsequent analyses we included only those number errors where the stem was produced correctly. It follows that FME did not show any pure number errors for the singular-dominant condition in the subsequent analyses (see Figure 2).