Refutation of Poffenberger's inference: an existence proof and a countermodel.

Interhemispheric relay time (IHRT) is inferred from simple (visual) reaction time (SRT) by subtracting SRTs in ipsilateral hand-field conditions from SRTs in contralateral hand-field conditions. This index, the "crossed-uncrossed differential" (CUD) is a synonym of IHRT in the current literature. The CUD has been shown to be significantly moderated by experimental variables, including attentional. One reason the CUD = IHRT hypostasy persists today is that no experimental manipulation has yet been able to generate a significantly negative CUD in a subject manifesting a significant positive CUD in classical conditions. We implemented an experimental manipulation, in SRT, consisting of increasing complexity of the response after the initial key press required at detection. In a very large scale single-case experiment, we found that the CUD thus went from significantly positive in classical SRT to significantly negative in the increased response load condition.

Facial morphology and children's categorization of facial expressions of emotions: a comparison between Asian and Caucasian faces.

The effects of Asian and Caucasian facial morphology were examined by having Canadian children categorize pictures of facial expressions of basic emotions. The pictures were selected from the Japanese and Caucasian Facial Expressions of Emotion set developed by D. Matsumoto and P. Ekman (1989). Sixty children between the ages of 5 and 10 years were presented with short stories and an array of facial expressions, and were asked to point to the expression that best depicted the specific emotion experienced by the characters. The results indicated that expressions of fear and surprise were better categorized from Asian faces, whereas expressions of disgust were better categorized from Caucasian faces. These differences originated in some specific confusions between expressions.

Right body side performance decrement in congenitally dyslexic children and left body side performance decrement in congenitally hyperactive children.

OBJECTIVE: Simple and complex visuomotor performance of the right and left sides of the body was investigated in 37 children with left hemisphere lesions, 35 children with right hemisphere lesions, 53 developmentally dyslexic children, 29 developmentally hyperactive children, and 35 "normal" children who had endured a very mild head injury with no sequelae. BACKGROUND: Lateralized soft signs, EEG topography, metabolic brain imaging, and neuropsychological test profiles suggest a predominance of left hemisphere dysfunction in dyslexia and right hemisphere dysfunction in hyperactivity. METHOD: Nine measures of lateralized performance were drawn from the Purdue pegboard, Letter cancellation, Rey complex figure, Wechsler Intelligence Scale for Children (WISC) Mazes, and WISC Picture completion tests. RESULTS: The children with left hemisphere lesions manifested significantly weaker performance on test components involving the right body side, relative to the normal controls, on the Purdue pegboard, Rey complex figure (delayed recall condition), and WISC Picture completion tests, and the dyslexic children on the former two. The children with right hemisphere lesions manifested significantly weaker performance on test components involving the left body side, relative to the normal controls, on the WISC Mazes test, as did the hyperactive children. CONCLUSIONS: We propose that (1) contralateral performance decrement results from a unilateral cortical lesion in children, and (2) developmental dyslexia may comprise a slight predominance of left hemisphere dysfunction and developmental hyperactivity of right hemisphere dysfunction.

Mania, pseudomania, depression, and pseudodepression resulting from focal unilateral cortical lesions.

OBJECTIVE: This consecutive multiple case study was designed to determine whether cortical lesion sites can predict occurrence of mood or psychomotor disorders in adults and children. BACKGROUND: Most of a large body of research supports the contention that left hemisphere lesions result more often than right ones in depression, and that the inverse occurs in mania. However, it is not clear how psychomotor status fits into this picture, nor whether children respond to the same lesions in a similar manner. METHOD: Published (n = 88) and unpublished (n = 31) cases of school-aged child and adult patients with focal unilateral cortical lesions and psychomotor agitation or lethargy with or without corresponding mania or depression were reviewed systematically to determine whether lesion location relates systematically to any of those psychiatric conditions. No patients had symptoms prior to detection of their lesion. Manic-depressives and agitated depressives were also excluded. RESULTS: Patients with mania and/or psychomotor agitation had predominantly right hemisphere lesions. Postlesion hyperactivity (without mania) in children was common but was not more related to lesions in one or the other hemisphere. Adult and child patients with depression and/or psychomotor lethargy had predominantly left hemisphere lesions. The intrahemispherical site of the lesion did not significantly predict the type of mood or psychomotor disorder. Nevertheless, the nonsignificant trend was for right posterorolandic lesions to predict mania or agitation and for left frontal lesions to predict depression or psychomotor lethargy. CONCLUSIONS: These findings support the neuropsychiatric approach to mood and psychomotor disorder in children and adults.