The aim of this contribution is twofold: first, a reply is given to Elmore and Tursky.1 who hypothesized that temporal pulse amplitude biofeedback (TPA) works on the basis of sympathetic activation. Contrary to this point of view, some data are reported supporting the opposite tendency: i.e. sympathetic deactivation. Secondly, based on the first part of this article, a new hypothesis is formulated with the intention of explaining temporal vasoconstriction simultaneously found with digital vasodilation and handtemperature increase during handwarming biofeedback (HTB) resp. during volitional handwarming/relaxation.1,11 This new hypothesis postulates that temporal vasoconstriction occurs during handwarming/relaxation due to the fact that peripheral extracranial scalp and face arterioles dilate. As a result, blood and oxygen supply as well as carbon dioxide release is increased, which leads in turn to a reduction in arteriolar ischemia, hypoxia and acidosis. The improved blood delivery from the temporal arteries to the extracranial arterioles and tissue provokes a relative degree of vasoconstriction of the temporal arteries.