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Behavioral Variability: Implications for Rehabilitation. John Whyte, MD, PhD Moss Rehabilitation Research Institute & Thomas Jefferson University. Clinical Case Examples. Minimally conscious state
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Behavioral Variability:Implications for Rehabilitation John Whyte, MD, PhD Moss Rehabilitation Research Institute & Thomas Jefferson University
Clinical Case Examples • Minimally conscious state • High variability in response rate and accuracy rate in command following and yes/no communication • Occasional dramatic cases of variability • Apraxia of speech • The patient does not lack the absolute capacity to produce specific speech sounds; they lack the ability to do so reliably
Treatment Implications • How much assessment does it take to characterize a patient’s current status or response to treatment? • How much safe performance guarantees safety after discharge? • Are there ways to work on consistency of performance other than working on overall quality of performance?
Research Examples • In our attention studies, central tendency of RT is strongly correlated with measures of dispersion in both patients and controls. • Transformations that are intended to eliminate this intrinsic correlation work poorly (either a positive correlation remains or becomes negative). • We’ve found it difficult to isolate a variability parameter and be confident it was not a statistical artifact.
Big Question #1 • Are we sure there is an independent phenomenon of a “variability deficit” vs. an intrinsic relationship between variability and central tendency?
Big Question #2: • What would constitute evidence for a separable impairment in “behavioral consistency”? • Ability to match subjects on central tendency (a thorny issue in itself) but find differences in variability? • Different neuroanatomic correlates for central tendency and variability? • Differential treatment responsiveness?