Individual differences in alpha rhythm as characterizing temperament related to cognitive performances

Cognitive performances of 'Differentiation-Generalization' processing were examined as to how they related to individual differences in cerebral alpha rhythm. Classification of types of temperament was made in accordance with the level of activation, which is isomorphic to the wave rhythm. It was claimed that one cycle of this wave can characterize a unit of capacity for the passage of information according to values of frequency and amplitude, and that this unit facilitates the mode of cognitive processing. Large or small units enable passage for many or few cues, which fit a differentiating or generalizing mode of processing, respectively. Twenty healthy subjects aged 21-40 years, 12 women and eight men, participated in this study. Alpha wave values were recorded and evaluated using a computerized EEG system, and performances of a global task and a global-analytic task bound to these modes of processing were examined. A linear relation, P < 0.01, was found between a high frequency of the alpha wave and an efficient performance of the global task. In classifying the subjects into four temperamental types according to high and low amplitude and frequency, differences were found in the chosen width of categorization: those who produced low frequency and high amplitude chose narrow, and those with high frequency and low amplitude chose wide, P < 0.025. It was speculated that the individual rhythm may reflect both the emotional and the cognitive aspects of behavior.