Progress in isolating the psychological factors contributing to the development of arterial hypertension has been retarded by the absence of suitable, non-invasive and continuous measures of significant aspects of cardiovascular activity. Pulse transit time may help to resolve this problem since it reflects changes in arterial elasticity and diastolic blood pressure. A method of recording pulse transit time is described. Significant decreases in pulse transit time were observed in response to a cold pressor test, a video game, a reaction-time task and problem solving, regardless of site of measurement or method of pulse transduction.