[EEG changes during the performance of verbal and non-verbal tasks]

EEGs were recorded from 12 positions of the scalp (10-20 system) in 30 normal right-handed subjects. Powers of alpha component obtained from contralateral loci during their performance of verbal tasks (definition of nouns, tongue twisting) and non-verbal tasks (memorization of shapes, imagination of a face) were compared. At the frontal and occipital regions, the right hemisphere dominance of the alpha component was more distinctly demonstrated during the verbal tasks than the non-verbal tasks, while at the occipito-temporal region, the left hemisphere dominance was distinctly demonstrated during the non-verbal tasks than the verbal tasks. However, the alpha components were dominant at the left occipito-temporal region during the verbal tasks and at the right frontal and occipital regions during the non-verbal tasks. The latter result was discussed in relation to the findings of Moss, Davidson, & Saron (1985) and noise generated by apparatuses. Component analysis was carried out for a correlation matrix made by four task variables and 12 samples of electrode positions. Two factors were derived; the first factor was loaded on the verbal tasks whereas the second factor on non-verbal tasks. The factor scores of the first factor were high at the right temporal region and those of the second factor at the left temporal region. These results proved the utility of principal factor method onto general patterns of alpha component during the tasks.