Relaxation is a low-cost treatment for managing pain with little or no side effects. The proposed study will use a novel biofeedback procedure to try to enhance the ability of relaxation to engage pain inhibition. Specifically, a biofeedback system will be used to provide training in conditioned pain regulation. The biofeedback system will monitor the trainee's level of sympathetic arousal and use it to control the intensity of painful stimulations delivered to the trainee during biofeedback. So when the trainee successfully relaxes (and reduced arousal), the intensity is lowered and produces pain relief. Efficacy of the training will be tested in a randomized controlled trial in which healthy, pain-free trainees are assigned to receive 3 training sessions or 3 sessions of a control procedure (2 other procedures will serve as controls; 3 groups total). The aim will be to assess whether the training results in inhibition of experimental pain and the nociceptive flexion reflex (NFR, a physiological marker of spinal pain signaling) to determine whether brain-to-spinal cord inhibitory circuits are engaged.