Assessment of perceived interpersonal stress based on EEG alpha response to competitive situations

Abstract

Interpersonal stress has various effects on individuals depending on their perception of the stressful situation. We focused on competitive situations as one of the interpersonal stressors in daily life, and we examined the effect of perceiving competitive situations in terms of electrophysiological responses. An electroencephalogram (EEG) was recorded during a cued reaction time task under solo and competitive situations with a visible opponent or an invisible opponent. Fast Fourier transform analysis was performed to compute absolute EEG alpha and beta power values. The alpha power ratio was calculated by dividing alpha power by alpha plus beta power and was then used to assess the participants' responses to interpersonal stress in competitive situations by examining the effects of time course on the alpha power ratio. To estimate the perception of competitive situations, participants' competitiveness was quantified using a questionnaire. Participants with lower third and upper third scores on the questionnaire were included in this analysis. For participants exhibiting low levels of competitiveness, the alpha power ratio of later trials was larger than that of earlier trials when competing with an invisible opponent, whereas there was no such temporal change when they were competing with a visible opponent. For participants with high levels of competitiveness, the alpha power ratio decreased in the competitive condition with a visible opponent compared with the solo condition, although there were few differences in their alpha power ratio between the competitive condition with an invisible opponent and the solo condition. These results suggest that less competitive individuals experience less stress in competitive situations although their arousal level is affected by awareness of their opponent. In contrast, competitive situations have greater impact on more competitive individuals owing to their high motivation for winning; invisibility of the opponent reduces their stress in competitive situations.