Pain-related Fear as a Facilitator of Nocebo Hyperalgesia

Before the start of conditioning, a mock skin-sensitivity test informs participants that their skin reacts to heat normally and it is safe for them to participate. A skin-sensitivity reading shows participants a scale that is in the green (no danger) zone.

Before the start of conditioning, a mock skin-sensitivity test informs participants that their skin is very sensitive and their nerve fibers are very responsive and they may have adverse reactions to the heat-pain application. A skin-sensitivity reading shows participants a scale that is in the red (higher danger) zone.

"During nocebo trials of the acquisition phase, conditioned stimuli (i.e., on-screen visual cues ON signaling the activation of sham electrical stimulation) are paired to unconditioned moderate-pain stimuli, to induce a negative association between the activation of electrical stimuli and an increase in pain. During control trials of the acquisition phase, the deactivation of the sham electrical stimulation (i.e., on-screen message OFF) is paired to 'baseline' pain of lower intensity."

"During nocebo trials of the acquisition phase, conditioned stimuli (i.e., on-screen visual cues ON signaling the activation of sham electrical stimulation) are paired to unconditioned high-pain stimuli, to induce a negative association between the activation of electrical stimuli and an increase in pain. During control trials of the acquisition phase, the deactivation of the sham electrical stimulation (i.e., on-screen message OFF) is paired to pain of lower intensity."

"During extinction, the previously conditioned nocebo effects on pain are attenuated by pairing the nocebo and control visual cues (i.e., on-screen messages ON and OFF) to pain stimuli of only lower intensity."