Older adults, individuals with dementia of the Alzheimer's type (DAT), and individuals with semantic dementia (SD) produced the past tense of verbs based on present-tense carrier sentences (e.g., Everyday I ding the bell. Yesterday I the bell). Both regularity (i.e., whether or noted is used for the past tense) and consistency (i.e., the degree to which verbs of similar orthography and phonology in the present tense have similar past tenses to the target) were manipulated. Participants received regular consistent (e.g., land-landed), regular inconsistent (e.g., weed-weeded), irregular consistent (e.g., sting-stung), and irregular inconsistent (e.g., light-lit) verbs. The dependent measures were overall accuracy rates and error rate types (e.g., regularizations, analogies, and other errors). Both consistency and regularity influenced performance. In addition, individuals with DAT showed a disproportionate deficit for inconsistent verbs associated with a high summed frequency of enemies, whereas SD individuals produced disproportionate breakdowns in performance on regular inconsistent, irregular consistent, and irregular inconsistent verbs. These results are consistent with the perspective that semantic/lexical processes are involved in processing the past tense of both irregular verbs and regular inconsistent verbs, and that attention is used to select appropriate responses and control inappropriate responses.
|Number of pages||21|
|State||Published - Sep 2006|
Bibliographical noteFunding Information:
This work was supported by NIA PO1 AGO3991 and NIA A605681. We thank Martha Storandt for providing the psychometric test support, John Morris and the Washington University Alzheimers Disease Research Center clinicians for their careful recruitment and description of the various participant groups. We thank Matt Lambon Ralph for helpful discussions regarding SD. In addition, we thank Avi Snyder for software involved in preprocessing MR images. Finally, we thank Karalyn Patterson and one anonymous reviewer for their comments on an earlier draft of this article.
ASJC Scopus subject areas
- Neuropsychology and Physiological Psychology
- Experimental and Cognitive Psychology
- Developmental and Educational Psychology
- Arts and Humanities (miscellaneous)
- Cognitive Neuroscience