Minutes

Bräscher, Anne-Kathrin; Kleinböhl, Dieter; Hölzl, Rupert; Becker, Susanne. (2017). Differential classical conditioning of the nocebo effect: Increasing heat-pain perception without verbal suggestions. Frontiers in Psychology, 8, 2163. https://doi.org/10.3389/fpsyg.2017.02163

Can your body learn to feel more pain, even when the painful stimulus itself never changes? 

German and Canadian researchers tested whether the nocebo effect (when learned associations cause negative symptoms) can emerge purely through unconscious conditioning. Twenty-six healthy volunteers took part, with 21 included in the final analysis. Each participant learned to associate one cue with painful heat and a different cue with non-painful heat before rating the intensity of subsequent heat stimuli and completing a behavioral task tracking shifts in perceived pain. 

Results? Once conditioned, participants rated identical heat as more painful when preceded by the "pain" cue despite no actual change in stimulation. Thirteen participants (62%) showed this learned nocebo effect. Curiously, their behavioral responses tell a different story, revealing a mismatch between what people report and how their bodies respond. 

Even more striking, conscious awareness of cues appears unnecessary. Most participants couldn't identify which cue predicted pain, yet the conditioned response still took hold. 

Lesson? Pain isn't just a readout of physical stimulation. It's shaped by learned associations, often below conscious awareness. Expecting a stove to be hot may cause discomfort. Likewise, cues surrounding treatment may quietly shape how symptoms feel, whether or not we notice.  

Written by Dan Peacock M.S.