Feedback evoked potentials during an auditory concept formation task.
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Thirty-two subjects with unilateral cerebral tumors were assessed for the use of hypotheses and cognitive strategies during a visual discrimination task. Subjects with frontal lobe lesions attained fewer concepts and used fewer appropriate hypotheses than subjects with tumors confined to the posterior hemisphere, although there was no difference in total hypotheses used. Lose-stay errors were committed with greater frequency among patients with frontal lobe lesions, although not all subjects with frontal lobe tumors exhibited this error tendency. The results of hypothesis sampling and a second visual discrimination transfer task suggested that the frontal lobe deficit was related to difficulty in attending to multiple cues and in monitoring feedback to segregate relevant from irrelevant sources of information.
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The authors studied reasons of a domineering perceptive generalizations in the Piaget test by children with schizophrenia. In teaching the children to distinguish and measure different properties of objects, the most typical appeared to be the following actions: a complete or partial refusal to accomplish them, a substitution of measurements by a perceptive comparison, difficulties in the narration of personal activity in well developed speech. Better results were attained in those who were emotionally positive. On these grounds the authors presumed an autistical genesis of these disturbances.
The study of thinking in patients with aphasic language impairments has long since been considered as means for learning about neuropsychological processes. In the present investigation, a non-verbal categorization task was used, requiring the subjects to sort several common objects according to different principles. The experimental group consisted of aphasic patients with motor and sensory aphasia. Two control groups were used, one consisting of normal subjects and the other of non-aphasic patients with injuries in the right hemisphere of the brain. The sorting behaviour was analysed according to several aspects. The final product of the categorization was assessed, as well as the behavioural processes observed during the sorting. The results were expressed in terms of different conceptual levels achieved. The results of the investigation showed that the aphasics were significantly inferior to normal controls both quantitatively and qualitatively in all sorting aspects. Possible mechanisms underlying the deficiencies in the sorting behaviour of the two aphasic groups were discussed.
To further investigate the usefulness of 3 purported measures of executive function (EF) in head injured children, we administered the Twenty Questions Test (TQT), Tower of London (TOL), and the Wisconsin Card Sorting Test (WCST) to 151 children who had sustained a closed head injury (CHI) of varying severity about 3 years earlier. In addition, we tested 89 normal controls. Fifty-seven of the patients were included in a longitudinal study that compared performance at 3 months and 36 months. All of the head injured children underwent magnetic resonance imaging for investigational purposes. Severity of CHI, as defined by the lowest Glasgow Coma Scale (GCS) score, affected performance on all 3 EF measures. Focal lesion volume incremented prediction of performance on TOL and WCST, but not TQT. Moderate intercorrelations of the test variables were obtained. Although all three EF measures depicted changes in performance over 3 years, a ceiling effect detracted from the sensitivity of the TOL to the impact of CHI on development. Implications of the findings for clinical applications are discussed.
After 30 days of operant training, with pecking responses to aerial photographs containing man-made objects reinforced with food, and no food reinforcement for pecking on photographs not containing man-made objects, a discrimination to the two classes of photographs was obtained. The discriminative response generalized to photographs with which the pigeons had no previous experience. This study demonstrates that pigeons are capable of forming relatively high-order concepts. Some possible stimulus properties controlling the discrimination are discussed.