Laughing and yawning can be contagious, but what about pain? We know expectations play a large role in the pain experience, so will your patient's pain perception change if they observe someone else experiencing pain? In this study, 88 healthy adults (18-35 years old) were randomly and evenly allocated to one of 3 experimental groups or a control group.
Each participant was informed that the study was assessing human responses to electrical stimuli. They could withdraw from the study at any time without providing a reason. Each participant completed a calibration phase to determine the pulse intensity level that would be detectable but non-painful. The control group then received two sessions of 15 pulses. The real-time group received 15 pulses independently and then 15 with a model (part of the research team who was disguised as another participant) and they rated the pain level (0-10) alternatively.
The post-hoc+ and post-hoc- groups completed their later 15 pulses after watching the model get 15 pulses and rate them. The model stayed for the + group and left for the - group. The results showed an allodynic effect with observing pain. All three observational groups experienced more pain. The real-time group had a 3.83 higher relative risk of experiencing pain than the control group (3.28 for + and 2.93 for -).
Keep these results in mind when there are multiple patients in the clinic at once. If one patient sees another grimacing or reporting pain during exercise or manual therapy, they may experience more pain when it is their turn to partake in that intervention.