Three Factor Analyses Of Electromyographic Data Under Varying Conditions

Electromyographic scores for seven muscles, systolic and diastolic blood pressure, heart rate, and galvanic skin resistance were obtained on 20 male and 24 female psychiatric clinic out-patients during three experimental conditions: rest, white noise, and psychological stress. Subjects also received 6 psychiatric ratings representing their response to the psychological stress. These ratings were included in all three score matrices. A principal component factor matrix was computed �or each of the conditions; these were rotated both orthogonally and obliquely. Muscles which are in close physical proximity tended to cluster much more on the analyses of scores obtained -during-rest and noise than during psychological stress. The pattern of heart rate and the two blood pressures varied with the conditions. Although the same rating scores were used for the three analyses, their loadings differed.