Learning disability subtyping: a reply to Adams.
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Humans↗
Biomedical subjects
W G Willis
Publications and source records attributed to W G Willis.
An alternative to interference indexes in neuropsychological time-sharing research.
Interference indexes are used as criterion measures in a significant proportion of time-sharing paradigms in order to control for the initial discrepancy between left- and right-handed tapping rates. Problems associated with these indexes include low reliability, low statistical power, and especially correlations with baseline tapping rates. An analysis of covariance procedure using raw-score concurrent tapping rates as criterion measures, and baseline tapping rates as covariates, can effectively address these problems as demonstrated through a reanalysis of data.
Functional Laterality↗
Lateralized interference effects: evidence for a processing style by modality interaction.
A time-sharing paradigm was used to study potential interference effects of concurrent successive-auditory/vocal, successive-visual/motor, simultaneous-auditory/vocal, and simultaneous-visual/motor tasks on right- and left-handed manual-motor behaviors of differential levels of difficulty. Participants were selected from each of three developmental levels from 9 through 20 years of age. Results suggested that processing style (i.e., successive or simultaneous) interacts with modality (i.e., auditory/vocal or visual/motor) in terms of lateralized interference effects; however, potential effects due to age level were obfuscated by differential concurrent-task difficulties.
Adolescent↗
Visual-spatial orientation, gaze direction and dichotic listening asymmetries.
The effects of visual-spatial orientation on dichotic listening performance were investigated in a sample of right-handed male and female adults. The 30 pairs of dichotic stimuli (/ba/ka/da/ga/ta/pa) were presented under three conditions: eye gaze fixed toward center, eye gaze directed 20 degrees to the right, and eye gaze directed 20 degrees to the left of center. Although no effect for gender or order was evident, a significant right ear advantage was found under all conditions. However, over all dichotic listening accuracy was significantly increased when visual-spatial orientation was directed to the right or left side of space.
Adult↗
Auditory-successive selective attention for learning disabled and normal boys.
Improvement in auditory-successive selective attention was noted across the age range of 9 through 16 yr. In contrast to comparable paradigms with visual-simultaneous materials, 30 learning disabled and 30 normal boys did not differ. Results of research on selective attention may be affected by task materials and encoding requirements.
Adolescent↗
Reanalysis of an actuarial approach to neuropsychological diagnosis in consideration of base rates.
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Brain Damage, Chronic↗
A guide for applying principal-components analysis and confirmatory factor analysis to quantitative electroencephalogram data.
Principal-components analysis (PCA) has been used in quantitative electroencephalogram (qEEG) research to statistically reduce the dimensionality of the original qEEG measures to a smaller set of theoretically meaningful component variables. However, PCAs involving qEEG have frequently been performed with small sample sizes, producing solutions that are highly unstable. Moreover, solutions have not been independently confirmed using an independent sample and the more rigorous confirmatory factor analysis (CFA) procedure. This paper was intended to illustrate, by way of example, the process of applying PCA and CFA to qEEG data. Explicit decision rules pertaining to the application of PCA and CFA to qEEG are discussed. In the first of two experiments, PCAs were performed on qEEG measures collected from 102 healthy individuals as they performed an auditory continuous performance task. Component solutions were then validated in an independent sample of 106 healthy individuals using the CFA procedure. The results of this experiment confirmed the validity of an oblique, seven component solution. Measures of internal consistency and test-retest reliability for the seven component solution were high. These results support the use of qEEG data as a stable and valid measure of neurophysiological functioning. As measures of these neurophysiological processes are easily derived, they may prove useful in discriminating between and among clinical (neurological) and control populations. Future research directions are highlighted.
Adolescent↗