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Biomedical subjects

W D Gouvier

Publications and source records attributed to W D Gouvier.

13 recordsLinked to original sources

Behavioral assessment and treatment of acquired visuoperceptual disorders.

Visuoperceptual deficits are common sequelae of damage to either hemisphere of the brain, but are typically more pronounced following injuries involving the right cerebral hemisphere. Common visuoperceptual disorders include visual field cuts, hemi-inattention and hemi-spatial neglect, hemi-perceptual deficits, and gaze and visual pursuit disturbances. A number of behavioral interventions have been developed to teach patients to compensate for acquired visual deficits. Studies addressing assessment and treatment issues in this area are reviewed, and future directions for research are outlined.

Agnosia

Wheelchair obstacle course performance in right cerebral vascular accident victims.

The initial experiment of this paper investigated the role of hemispatial neglect in wheelchair-related accidents of right-hemisphere stroke victims. Twelve subjects with and 12 subjects without neglect of left space drove their wheelchairs through an obstacle course. Two types of obstacle course errors were evaluated: direct hits and sideswipes. The neglecting group made significantly more direct hits but there were no significant differences between groups in sideswipe errors. In Experiment 2, the nonneglecting group's data were compared with a left-hemisphere stroke group without neglect and three motor control groups to investigate if their errors resulted from motor deficits. The right-hemisphere stroke group made significantly more left-sided errors and errors in contralateral space than any other group. In Experiment 3, 13 subjects with neglect were taught to scan to the left which resulted in significant decreases in direct hits but not in sideswipes on the obstacle course. These results suggest that obstacle course performance is sensitive to more than hemispatial neglect.

Accident Proneness

Psychometric prediction of driving performance among the disabled.

A battery of psychometric and performance tests was administered to 25 subjects who were classified into able-bodied (n = 8), brain-injured (n = 10), and spinal cord injured groups (n = 7). All disabled subjects were regarded by their referring rehabilitation therapists as potential candidates for driver assessment. Data were analyzed to identify which measures were useful in differentiating among the groups and predicting driving performance. Results indicated that psychometric measures can be useful in predicting driving performance among disabled drivers. Nearly all the measures in the battery were significant predictors of driving ability, and some were highly predictive. The best was the oral version of the Symbol Digit Modalities test, which by itself accounted for 70% of the variance of the full-sized-vehicle driving score. Adding a second variable into a two-step multiple regression further increased the correlation between predictors and driving, accounting for almost 80% of the variance in driving score. These findings support the feasibility of developing a simple test battery to determine which disabled candidates are ready for in-vehicle assessment, and which candidates are not ready without further evaluation of cognitive and performance skills.

Adolescent

Measures of central tendency, variability, and relative standing in nonnormal distributions: alternatives to the mean and standard score.

There are two major disadvantages to reporting test results in standardized scores such as z-scores or t-scores when describing individuals with disabilities. (1) Raw scores on many tasks from disabled individuals are notoriously nonnormal. They are asymmetric, in that they are skewed toward poor scores. (2) Low z-scores give a false impression of dysfunction because able-bodied subjects are often grossly overqualified for the application in question; they may have levels of strength or quickness several orders of magnitude greater than what is needed to do the assessment task. A recommended alternative is to describe the performance of disabled individuals using nonparametric statistics, and to report scores in boxplots, showing the extremes, the median, and the quartiles. Such points are easy to calculate and to interpret, and they are robust against outliers.

Disability Evaluation

Sex differences in visual information processing following right cerebrovascular accidents.

This study examined whether males and females who had sustained right CVA's but did not show gross asymmetries in processing left- and right-sided visual information would demonstrate visual hemiimperception when tested with more demanding evaluation procedures. Testing involved tasks of reaction time, oral reading and searching for embedded words and figures. Males and females differed in their response patterns for tasks involving searching for embedded target stimuli; specifically, males required greater lengths of time to locate stimuli in left hemispace, while females showed no such pattern of results. This suggests that closer attention must be paid to screening procedures used to detect hemispatial visual imperceptions, particularly among males.

Adult

A small-scale vehicle for assessing and training driving skills among the disabled.

A small-scale vehicle (SSV) was developed to assess and train skills of disabled individuals who wish to become licensed to drive. The SSV incorporates power-assisted adjustable-effort steering and braking functions, variable-speed control, modular interchangeable hand control units, standard foot-control units, and a variety of safety and instrumentation features. This vehicle offers numerous advantages over traditional modes of assessment and training. These advantages include its lower price and operating costs as compared to a full-sized vehicle; its adaptability to left- or righthanded clients; and the provision of a specially adapted vehicle for vehicle for practice driving and regaining skills and self-confidence away from public thoroughfares. The SSV is one component in the Center's driving assessment and education curriculum that follows a graded progression, beginning with use of a driving simulator, to driving the SSV, to driving a full-sized vehicle.

Automobile Driving

Reliability and validity of the Disability Rating Scale and the Levels of Cognitive Functioning Scale in monitoring recovery from severe head injury.

The Disability Rating Scale (DRS) and the Levels of Cognitive Functioning Scale (LCFS) are both widely used to monitor recovery from head injury, despite the total lack of published research on the reliability and validity of the LCFS, and the fragmented and incomplete reports on these characteristics of the DRS. Forty head-injured inpatients were evaluated with the DRS and LCFS four times weekly throughout their rehabilitation hospitalization. The DRS and LCFS were compared in terms of how consistently ratings could be made by different raters, how stable those ratings were from day to day, their relative correlation with Stover Zeiger (S-Z) ratings collected concurrently at admission, and with S-Z, Glasgow Outcome Scale (GOS), and Expanded GOS (EGOS) ratings collected concurrently at discharge, and finally in the ability of admission DRS and LCFS scores to predict discharge ratings on the S-Z, GOS, and EGOS. Results suggest that both scales possess significant degrees of test-retest and interrater reliabilities, and of concurrent and predictive validities, but the DRS surpasses the LCFS in nearly every regard. These results offer psychometric justification favoring the use of the DRS for monitoring recovery from head injury.

Adult

Behavior modification in physical therapy.

Behavioral techniques reported to improve ambulation skills among physically handicapped persons include both reward and desensitization procedures. This report describes the application of other behavior modification principles to two patients who resisted physical therapy (PT) designed to educate them in the use of orthopedic assistive devices. Peer modeling was used with case 1, a 2 1/2-year-old girl with complete L4 spina bifida who cried frequently when wearing her brace, and refused to walk except with much assistance. Case 2 was a 21-year-old hemiplegic man seen two years after a severe head injury. Initially, severe tantrum behavior accompanied all demands placed on him. Treatment involved a combination of contingent music for being quiet and contingent aversive auditory feedback for yelling. In both cases clinically significant behavioral changes were observed. Results are discussed with respect to the cost effectiveness of behavioral interventions and the interdisciplinary coordination of rehabilitation team members.

Adult

Dependent variables in rehabilitation research.

It is important that rehabilitation professionals use appropriate techniques to evaluate their treatments. False, contradictory, diverse, and misleading interpretations can be obtained depending on how dependent variables in treatment outcome research are quantified. This report describes an evaluation of a single-subject investigation that used a push-up timer for teaching pressure relief maneuvers. Results are analyzed four separate ways, and can be taken to support three quite different conclusions. This illustrates that investigators should carefully select procedures of analysis before initiating a study to avoid having to make a post hoc and potentially biased selection of which mode(s) of data analysis and presentation is most appropriate. However, such an a priori selection of analysis does not relieve investigators of the responsibility for analyzing their data from different perspectives and discussing alternate or contradictory interpretations.

Adult

Assessment of drug state dimensionality via drug-drug training and stimulus generalization testing.

A procedure for determining whether different drugs share a common stimulus dimension is described. This procedure uses the presence of post-discrimination generalization gradient asymmetry as an indication that the training stimuli lay along a common stimulus dimension. Separate groups of hungry pigeons were trained to discriminate a 15 mg/kg dose of phenobarbital which was associated with frequent food reinforcement (S+) from each of 9 different drug conditions which were associated with infrequent reinforcement (S-). S- stimuli were selected to represent a drug from a completely different class (amphetamine), a drug with biphasic effects which may partially correspond with the effects of phenobarbital (delta 9-THC), and a drug from the same class as the S+ (pentobarbital). Following discrimination training subjects were tested for generalization to five dosage levels (5, 10, 15, 20, 25 mg/kg) of phenobarbital. Steep symmetrical generalization gradients around the S+ indicated that delta 9-THC and d-1-amphetamine were both quite discriminable from phenobarbital, and that they were perceived by subjects as representing stimulus dimensions different from phenobarbital, and that it was perceived as lying on a stimulus dimension common to phenobarbital. This procedure may allow better understanding of how different drug states are perceived by animals as similar or dissimilar.

Amphetamines