The control of pulse transit time independently of interbeat interval by providing feedback from both.

Sixteen subjects took part in a two-stage cardiovascular biofeedback experiment. For five sessions all subjects attempted to control their pulse wave transit time (TT), using TT feedback. The eight subjects who achieved control were given a further five sessions, during which they attempted to control their transit time without altering their interbeat interval (IBI) when provided with TT and IBI feedback. No evidence was found for complete dissociation of TT and IBI. When the single TT contingency was in operation, all subjects who had significant control of TT also showed significant changes in IBI in the same direction. When the dual contingency was introduced, subjects either controlled TT but failed to keep IBI stable or kept IBI stable but failed to control TT.