The discrimination of blood pressure fluctuations.

Two studies are described in which volunteers were trained to distinguish between displays contingent on or independent of blood pressure fluctuations. The latter were monitored with pulse transit time (TT). In Experiment 1, subjects were required to choose between TV displays that either reflected instantaneous TT or variations recorded a few minutes earlier in the session. Accurate discrimination was rapidly acquired. In Study 2, the choice was between signals dependent on TT or interbeat interval. Only one out of six subjects was successful. In both cases, associations between display fluctuations and respiratory activity were employed by subjects for distinguishing signal origin. The use of contingency discrimination strategies for assessing cardiovascular perception is discussed.