Current Research Projects
Anomia is a core feature of aphasia, a disorder affecting at least 2.5 million Americans. Anomia makes spoken communication very difficult, and causes major problems for both patients and for their caregivers. Assessment of naming ability is foundational to both research and clinical practice in aphasiology, but currently available naming tests have largely failed to capitalize on important advances in psychometric theory and natural language processing over the past 50 years. The goal of this NIDCD funded project is to develop a series of algorithms for the automatic detection and classification of paraphasias -word errors that are typically the result of anomia. Our goal is to develop the necessary machinery to detect and characterize an individual’s anomia based on standardized tests as well as discourse. This will open the door to many new ways of treating anomia, and has the potential to substantially reduce clinical workload. PIs: Bedrick & Fergadiotis
NIDCD R01
Algorithmic Classification of Paraphasias
NIDCD R01
Assessment of Anomia:
Improving Efficiency & Utility
Using Item Response Theory
To be optimally useful, novel metrics of anomia must be validated within a rigorous psychometric framework to (i) efficiently provide information about both overall severity and the underlying cognitive deficits in a unified framework, (ii) support repeated assessments without threatening internal validity or measurement precision, (iii) target both object and action naming, and (iv) easily integrate into computerized adaptive testing platforms. All current anomia tests lack at least one of these features. This project pursues three aims:
First, to ease sharing of information across clinics and labs, and enhance the ability to conduct robust meta-analytic studies, five object picture-naming tests will be equated within an item response theory framework, and their scores will be expressed on the same metric. Further, to obviate the need for large samples in future item development, a model for predicting the difficulty of most picturable nouns will be refined and cross-validated. Just as the measurement of length does not depend on which ruler is used, measurement of anomia severity need not depend on which naming test is given.
Second, to quantify the underlying cognitive deficits of anomia, a cognitive-psychometric model of anomia will be refined and evaluated to produce a measurement model that balances clinical utility, model-data fit, and fidelity to current theory.
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Third, given the increasingly recognized importance of action naming, a computer adaptive action naming test will be developed using item response theory by modeling action naming responses; regressing verb item difficulty parameters on relevant target properties; and, conducting real-data simulations to assess the precision of the computer adaptive test engine. PIs: Hula & Fergadiotis
A significant proportion of persons with aphasia are bilingual, given that nearly one-fifth of the U.S. population and over one- half of the world’s population is bilingual. The overlap in language behaviors between bilinguals of varying proficiency and persons with aphasia makes the diagnosis of bilingual aphasia particularly challenging. Yet, there are hardly any psychometrically valid diagnostic instruments to diagnose aphasia and differentiate it from the language variation seen across bilinguals. Over two-thirds of clinicians in the U.S. report being unprepared to assess bilingual adults due to unavailability of valid diagnostic tools and insufficient understanding of bilingual language disorders. The proposed research represents the first systematic psychometric investigation of clinical language measures in English for Spanish-English speaking bilingual adults across multiple language domains. The project will establish language measures, population norms and cut-off scores with a three-fold purpose: identification of aphasia, diagnosis of morphosyntactic and lexicosemantic impairments in aphasia. The outcomes of this project will improve diagnostic accuracy and therefore reduce health disparities for bilingual adults with aphasia. PI: Yasmeen Faroqi Shah. Role: Consultant