Muscle tension, skin conductance, and finger pulse volume: asymmetries as a function of cognitive demands

Previous studies of physiological asymmetries induced by cognitive tasks have focused on a single physiological measure at a time and have failed to relate physiological asymmetries to levels of performance on the asymmetry-inducing tasks. The present study recorded surface muscle tension (EMG), skin conductance (SC), and finger pulse volume (FPV) from the left or right sides of 28 right-handed college students during two left- (Verb Memorization and Lyric Recitation) and two right-hemispheric tasks (Facial Memorization and Humming). EMG and FPV asymmetries as a function of tasks were discovered, with the directionalities of these asymmetries consistent for both left- and right-hemispheric tasks. EMG was shown to be reduced and FPV increased on the side contralateral to the hemisphere required for task-related processing. The consistency between these findings and predictions by Walley and Weiden (1973) and Kahneman (1973) are discussed. No significant SC asymmetry as a function of tasks was observed. It was found that factor variates obtained from principle components analyses of physiological measures recorded from the left or right sides during Verb Memorization and Facial Memorization were marginally successful in predicting verb and facial recognition performance.