[Show abstract][Hide abstract] ABSTRACT: PURPOSE: To evaluate the dimensionality and measurement invariance of the aphasia communication outcome measure (ACOM), a self- and surrogate-reported measure of communicative functioning in aphasia. METHODS: Responses to a large pool of items describing communication activities were collected from 133 community-dwelling persons with aphasia of ≥ 1 month post-onset and their associated surrogate respondents. These responses were evaluated using confirmatory and exploratory factor analysis. Chi-square difference tests of nested factor models were used to evaluate patient-surrogate measurement invariance and the equality of factor score means and variances. Association and agreement between self- and surrogate reports were examined using correlation and scatterplots of pairwise patient-surrogate differences. RESULTS: Three single-factor scales (Talking, Comprehension, and Writing) approximating patient-surrogate measurement invariance were identified. The variance of patient-reported scores on the Talking and Writing scales was higher than surrogate-reported variances on these scales. Correlations between self- and surrogate reports were moderate-to-strong, but there were significant disagreements in a substantial number of individual cases. CONCLUSIONS: Despite minimal bias and relatively strong association, surrogate reports of communicative functioning in aphasia are not reliable substitutes for self-reports by persons with aphasia. Furthermore, although measurement invariance is necessary for direct comparison of self- and surrogate reports, the costs of obtaining invariance in terms of scale reliability and content validity may be substantial. Development of non-invariant self- and surrogate report scales may be preferable for some applications.
Quality of Life Research 06/2012; · 2.86 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: To examine the dimensionality of scales for measuring patient-reported cognitive and communicative functioning in a sample of stroke survivors and to evaluate the consequences for measurement of treating them as a single, undifferentiated construct.
Secondary analysis of existing cross-sectional data.
Data were collected in outpatient rehabilitation clinics and in the community.
Unilateral stroke survivors (N=316) 3 months or more postonset referred for participation in research.
The Burden of Stroke Scale cognition and communication domain scales were evaluated by using confirmatory factor analysis, Rasch analysis, and tests of differential item functioning (DIF). To evaluate the impact of multidimensionality on the measurement of individual patients, separately estimated cognition and communication scores were compared. Combined and separately estimated scores were also examined for responsiveness to group differences in the presence of cognitive and communicative impairment.
Factor analysis and Rasch model fit analyses equivocally supported the unidimensionality of the item pool. DIF analyses between participants with right versus left hemisphere stroke suggested multidimensionality. Scaling cognition and communication items separately resulted in different person scores for a significant number of patients and greater responsiveness to group differences.
Patient-reported scales assessing communication along with more general cognitive activities may possess an internal structure that is inconsistent with a unidimensional measurement model with potential negative consequences for measurement.
Archives of physical medicine and rehabilitation 03/2010; 91(3):400-6. · 2.18 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Background: Item banking, an approach to test development based in item response theory (IRT), is beginning to be applied to the measurement of communicative functioning in aphasia. This approach involves calibrating a set of test items responding to a particular latent trait to a common measurement scale. One method for validating such scales is to examine the degree to which obtained item calibration estimates agree with a priori item rankings based on theory or expert opinion.Aims: The purpose of this study was to evaluate the utility of magnitude estimation (ME) procedures for validating item banks containing self‐reported functional performance items, and to make a preliminary analysis of the validity of a proposed item pool for measuring self‐reported communicative functioning in aphasia.Methods & Procedures: A total of 14 raters made ME ratings of physical and communicative functioning items. These ratings were evaluated for their intra and inter‐observer reliability and, for subsets of the items, their correspondence with previously published IRT calibration estimates was also evaluated.Outcomes & Results: Intra‐rater reliability was moderate to high, and inter‐rater reliability was high. Correspondence with IRT calibrations was high for physical items, and moderate for communication items. The distribution of ME ratings for the communication items was negatively skewed.Conclusions: ME procedures have utility for investigating the validity of functional performance items. The results suggest that communicative functioning may have a more complex latent structure than physical functioning, and that the proposed item pool might benefit from the inclusion of additional items at the lower end of the scale.
[Show abstract][Hide abstract] ABSTRACT: There has been renewed interest on the part of speech-language pathologists to understand how the motor system learns and determine whether principles of motor learning, derived from studies of nonspeech motor skills, apply to treatment of motor speech disorders. The purpose of this tutorial is to introduce principles that enhance motor learning for nonspeech motor skills and to examine the extent to which these principles apply in treatment of motor speech disorders.
This tutorial critically reviews various principles in the context of nonspeech motor learning by reviewing selected literature from the major journals in motor learning. The potential application of these principles to speech motor learning is then discussed by reviewing relevant literature on treatment of speech disorders. Specific attention is paid to how these principles may be incorporated into treatment for motor speech disorders.
Evidence from nonspeech motor learning suggests that various principles may interact with each other and differentially affect diverse aspects of movements. Whereas few studies have directly examined these principles in speech motor (re)learning, available evidence suggests that these principles hold promise for treatment of motor speech disorders. Further research is necessary to determine which principles apply to speech motor (re)learning in impaired populations.
American Journal of Speech-Language Pathology 09/2008; 17(3):277-98. · 1.64 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Two studies examined speech skill learning in persons with apraxia of speech (AOS). Motor-learning research shows that delaying or reducing the frequency of feedback promotes retention and transfer of skills. By contrast, immediate or frequent feedback promotes temporary performance enhancement but interferes with retention and transfer. These principles were tested in the context of a common treatment for AOS.
Two studies (N = 4, N = 2) employed single-subject treatment designs to examine acquisition and retention of speech skills in adults with AOS under different feedback conditions.
Reduced-frequency or delayed feedback enhanced learning in 3 participants with AOS. Feedback manipulation was not an influential variable in 3 other cases in which stimulus-complexity effects may have masked treatment effects.
These findings demonstrate that individuals with AOS can benefit from structured intervention. They provide qualified support for reduction and delay of feedback, although interaction with other factors such as stimulus complexity or task difficulty needs further exploration. This study adds to the growing body of literature investigating the use of principles of motor learning in treating AOS and provides impetus for consideration of pre-treatment variables that affect outcome in treatment studies.
Journal of Speech Language and Hearing Research 09/2008; 51(5):1088-113. · 1.93 Impact Factor