Skin color and autonomic nervous system measures

A study has been performed in 50 subjects, 25 white and 25 black, measuring skin color (PI), basal skin resistance (SR) and amplitude of the galvanic skin response (GSR), and resting heart rate (HR) and the heart rate response (HRR) induced by a startle tone. A multiple correlation matrix revealed a statistically significant relationship between PI and SR and also GSR; between HR and HRR, and between SR and GSR. Analysis of the group differences revealed that blacks had significantly lower (darker) PI values, higher SR, greater GSR, and a higher HR and HRR. It is unclear from this study whether race or the intensity of skin color influenced the measured physiological responses.