Computer tomographic localization, lesion size, and prognosis in aphasia and nonverbal impairment.

Computerized tomography scans (80) were used to localize infarcts in 70 patients. Twenty-three aphasics were scanned within 35 days from onset, 39 beyond a year, and 18 were nondominant cases. Aphasics were also grouped according to test scores obtained within 35 days of scan. Chronic global aphasics have larger lesions than persisting Broca's aphasics. The area of persisting Broca's aphasia is similarly anterior but larger than that of recovered motor aphasia. Anomic aphasics evolve from Broca's and Wernicke's types with differing localization. Lesion size correlated with severity and recovery, and comprehension among the subtests.     

The usefulness of distinguishing between a defensive and a nondefensive external locus of control

The study's purpose was to determine whether a distinction can be made between individuals adopting an external locus of control as a defense and those adopting the orientation because it reflects their life experience. It was hypothesized that the two groups differ in the amount of personal responsibility they accept for task outcomes. Internals and externals were identified and then further designated as high or low in action taking. Among externals, a high action-taking score implied defensiveness. Subjects randomly received either success or failure feedback on a presumed task of interpersonal sensitivity. Defensive externals varied their causal attributions as a function of outcome, whereas nondefensive externals did not (p < .05). The distinction between defensive and nondefensive external control was thus supported.     

A general framework for the analysis of concept identification tasks

A general framework is presented for concept identification based on hypothesis-testing theory. It is a modification of the duoprocess theory presented by Chumbley (1972). It is shown how Markov models for various complex concept identification tasks may be derived from this framework and how such models may be analyzed by making use of probability generating functions. Two experiments are described. In experiment 1 three tasks were used: two simple tasks, where the subject either only had to select the relevant dimension in order to solve the problem or only had to learn a short list of paired-associates, and a more complex task, where both processes were needed to reach the solution. The results were in general favorable to the theory. Experiment 2 was designed to test the application of the theory to the four-choice concept problem. The predictions of the theory are compared to those of the subproblem learning theory of trabasso and Bower (1964), modified to include a ‘learning-on-errors’ assumption. The fit of the duoprocess theory was reasonably good and superior to that of the subproblem learning theory.     

The self-attention-induced feedback loop and social facilitation

It has been proposed that self-directed attention leads to the engagement of a cybernetic feedback loop, by which discrepancies between present behavior and a standard of comparison are reduced. This analysis is applied to performance facilitation effects, which are more typically explained in terms of drive theories. Though these two approaches to motivation make similar behavioral predictions in this context, they assume different mediating states. Support is noted for the assumptions that mirror presence and audience presence induce self-focus, and that they lead to comparison with salient behavioral standards. Support for the assumption that these manipulations increase arousal is also reviewed, and is challenged on methodological grounds. The attentional analysis is used to derive predictions regarding changes in physiological state over the course of a typical social facilitation procedure. An experiment is reported which confirmed these predictions. Discussion centers on how to interpret physiological changes in terms that are compatible with control theory, how to account for social impairment phenomena in terms of the present model, and the conceptual relationship between mirror presence and audience presence as experimental manipulations.     

Learning disability and hyperactivity: Deficits in selective attention

Differences in performance on a variety of cognitive measures and differences in patterns of ability between learning disabled (LD) and nonlearning disabled (non-LD) children were examined. Younger and older LD and non-LD children were administered tests of central and incidental learning and selective attention. Teacher ratings of classroom hyperactivity were also examined. LD children, particularly the younger ones, performed significantly more poorly than non-LD children on both attention/memory tasks. Performance on the two tasks was consistently interrelated for the non-LD children and less consistently so for the LD subjects. Hyperactivity was also related to poorer performance on the cognitive measures. Results are discussed in terms of components of selective attention.     

Cluster analysis in school psychology: An example

This investigation demonstrates the use of Ward's method of cluster analysis to uncover the underlying classification structure in a group of children (N = 200) referred for psychological evaluations by their public school teachers. Data were acquired on children's intellectual development, academic achievement, and social adjustment. The cluster solution identifies six groups of children which are statistically distinct. All three measurement areas are important in distinguishing among the different groups. The six-group solution accounted for appreciable amounts (95%) of the variability in the three measurement areas. Implications for psychologists working in the schools are discussed.     

Quantitative CT scan studies in aphasia. I. Infarct size and CT numbers

Infarct si?e (number of 1-mm² pixels in the lesion) on CT scans of 30 aphasia patients was obtained with a semiautomated computer program. The mean number of lesion pixels present per slice containing lesion was approximately 500 for mild aphasias (transcortical motor and conduction), 700 for Wernicke's, 1000 for Broca's, 1500 for mixed, and 2000 for globals. These differences were significant for $\text{11}\text{15}$ of the group pairwise comparisons. When lesion locus was controlled for in the anterior/posterior plane, 73–100% of the aphasia patients were correctly classified as to type of aphasia by a discriminant analysis utilizing only the number of lesion pixels present on two CT slices. Different slice combinations were used for different aphasia group comparisons. There was a significant correlation between severity of aphasia and lesion size. There was a significant correlation between lesion size and the CT numbers in the lesion. This type of analysis may be useful to predict the prognosis for recovery potential in aphasics who have CT scans performed at 2 months poststroke.