Classical conditioning of the human blood pressure response

The object of this experiment was to demonstrate that blood pressure responses could be classically conditioned in human subjects and to describe the topography of the conditioned response. Despite clear evidence for classical blood pressure conditioning in animals there is little evidence concerning a clear demonstration of the phenomenon in human subjects, and no description of the form of the conditioned response. A 'neutral' 8-s 70-db tone (CS) was paired with a 500-ms electric shock (UCS) in a delay conditioning paradigm. Conditioned subjects were compared to a control group that received the CS and UCS on a truly random schedule. The subjects in the conditioning group showed a conditioned blood pressure response that emerged during the last 4 s of the 8-s CS. The results differ from those obtained from animals, where the CR typically emerges during the first half of the CS. These data may have implications for the role of learning in hypertensive disorders.