Biomedical subjects
Publications and source records attributed to R R Robey.
The factual basis for the central assertion made by Nye, Lorch, and Whurr (1997) is carefully examined. Although the assertion is not warranted, the new information brought forth by Nye et al. (1997) is a welcomed development.
An extensive search of aphasia-treatment literature yielded 55 reports of clinical outcomes satisfying the essential criteria for inclusion in a meta-analysis. The results confirmed those of an earlier meta-analysis in demonstrating the utility of aphasia treatments, generally considered, for bringing about desirable clinical outcomes. Beyond the general case, the new findings address clinical utility in finer detail than was previously possible. Effects of treatment for aphasia are synthesized and assessed for each of four important dimensions: amount of treatment, type of treatment, severity of aphasia, and type of aphasia.
Throughout the educational, medical, psychological, and social sciences, meta-analysis is the present-day, broadly accepted means for combining many quasi-experiments in a synthesis for the purpose of establishing the weight of scientific evidence bearing on a certain research question. Meta-analysis thereby is the preferred method for determining the preponderance of evidence in clinical-outcome research relating to questions of treatment efficacy and treatment effectiveness. Relatively few meta-analyses appear in the literature of the communication disorder sciences. The purpose of this tutorial is to enhance the familiarity and accessibility of this technology in the domains of audiology and speech-language pathology. The results of the accompanying example constitute a preliminary meta-analysis of patient-perceived treatment effectiveness. The substance of the tutorial, however, transcends disciplinary interests regarding types of communication disorder.
The variability, both between subjects (intersubject variability) and within subjects (intrasubject variability), of the P300 event-related potential was compared to that of early and middle latency components using coefficients of variation. For each of five waveform components, 12 amplitude measures (two trials on each of six measurement occasions) and 12 latency measures were obtained for each of eight subjects. P300 intersubject variability was comparable to that of the most stable early components (ABR waves III and V), both in terms of amplitude and latency. Intrasubject variability was considerably greater for P300 than for the early components; even so, multiple waveforms collected from the same subject tended to fit within an envelope bounded by +/- 1 standard deviation form the mean (averaged) response to oddball stimuli. The variability of MLR component Pa exceeded that of all other components.
Central to theories of speech motor control are estimates on magnitudes of lip activity expressed in terms of central tendency, variability, and interrelatedness. In fact, the tenability of each of two competing theories of motor control for speech production rests solely on the observation of the predicted direction of the correlation coefficient (one positive and one negative) that indexes the relationship of concurrent lip activity. Each theory, however, predicts a relationship that is the complete opposite of the relationship predicted by the other. That is, one theory proposes that the labial system functions on the basis of complementary variation, whereas the other assumes positive covariation, or complementary modulation. In apparent contradiction, each prediction has been observed under laboratory conditions. The explanation for this apparent contradiction resides in the small sample sizes upon which each estimate was based. The minimum number of observations that are necessary to achieve accurate estimates of lip displacement parameters has remained unclear. This paper addresses three fundamental questions: (a) how many observations of on-task behavior are necessary to accurately estimate mean and variance values for the magnitude of upper lip displacement in a speech production experiment?, (b) what is the analogous number of observations for estimating the same values of lower lip displacement (together with the mandible) in the same context?, and (c) how many observations are necessary to accurately estimate the correlation coefficient indexing the relationship of lip displacements during the production of speech? Answers to these questions are accomplished through a review of estimator properties, a Monte Carlo computer simulation, and through laboratory observations.(ABSTRACT TRUNCATED AT 250 WORDS)
A meta-analysis of research findings is reported on the effectiveness of treatments for persons suffering aphasia. Twenty-one studies provided sufficient information for inclusion in the analysis. The magnitudes of three classes of effect sizes were estimated: untreated recovery, treated recovery, and treated versus untreated recoveries. The outcomes witness the clear superiority in performance of persons receiving treatment by a speech-language pathologist.
Repeated measures designs should be used more frequently in prevention intervention research. They are the design of choice when one or more measurements have been taken at baseline followed by one or more measurements after prevention intervention. They may be used to ask questions about differences on measurements at different points in time and between measures made on the same scale. In this presentation, prevention intervention researchers are provided with a step-by-step discussion of this design, examples of prevention intervention repeated measures designs, and a discussion of the misuses of this design.
Auditory masking effects on lingual vibrotactile thresholds were examined across three groups of 10 subjects each. The first group included children 13 yr. of age or younger, the second group young college age adults, and the third group elderly individuals 66 yr. of age or older. Lingual vibrotactile thresholds were obtained from each group at a frequency of 250 Hz, under experimental conditions of no-masking, narrow-band masking, and wide-band masking. Results showed statistically significant threshold differences between the elderly group and the other two groups for all three experimental conditions. A difference was also detected between experimental conditions when an over-all statistical analysis was performed, but this difference disappeared under more stringent post hoc examination. Results are discussed with respect to current literature on aging and appropriate simplified procedures are recommended for future lingual vibrotactile threshold testing.
Effects of duration of stimulus exposure on lingual vibrotactile thresholds were examined across three groups of 10 subjects each (n = 30). Subjects were grouped according to age (child group, mean age = 10.1 yr.; young adult group, mean age = 21.9 yr.; elderly group, mean age = 76.0 yr.). Lingual vibrotactile threshold measurements were obtained for all subjects under 5 conditions of exposure (1, 2, 3, 4, and 5 sec.). Results showed statistically significant differences in threshold among all three age groups. As age increased, thresholds of lingual sensitivity increased (became poorer). Stimulus duration also created significant differences in threshold for all age groups. As stimulus duration increased, thresholds of lingual sensitivity decreased (became better). The children appeared to be the most stable across conditions whereas the elderly group appeared to be the most affected by stimulus duration.
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