Sensory, emotional, and cognitive cues, rather than an objective, physiological source, may be among the factors that significantly influence how pain is experienced. Those are the conclusions of a test that used virtual reality to misrepresent how far the neck is turned, and ultimately change the pain experiences among individuals affected by chronic neck pain.
The findings appeared recently in Psychological Science, and are said to indicate that altering the visual cues that inform the brain about the body can impact pain.
“Our findings show that the brain does not need danger messages coming from the tissues of the body in order to generate pain in that body part — sensible and reliable cues that predict impending pain are enough to produce the experience of pain,” says researcher G. Lorimer Moseley of the University of South Australia.
For their tests, Moseley and a group of colleagues reportedly recruited 24 chronic neck pain sufferers from physiotherapy clinics. The participants had experienced the pain for an average of 11 years, stemming from issues including posture, tension, repeated strain, trauma, and scoliosis.
The researchers had participants sit in a chair while wearing a virtual reality head-mounted display. The display showed a virtual indoor or outdoor scene while simultaneously recording participants’ head movements using gyroscopes. The participants wore a seat belt that prevented them from moving their torso, and they also wore headphones that blocked out incidental noise.
For each scene that was presented, the participants were asked to rotate their head left or right, until they experienced pain. What the participants didn’t know was that on some trials the researchers were manipulating the visual feedback provided in the virtual world so that it didn’t accurately represent the degree to which the head was turned. In some cases, the scene indicated that participants weren’t turning their head as far as they actually were — it understated the degree of rotation. In other cases, the feedback indicated to participants that they were turning their head farther than they were, overstating the degree of rotation.
The results showed that the visual feedback played an important role in determining when the participants reported feeling pain.
When the display understated actual head rotation, participants had a broader range of pain-free motion; they were able to turn their head about 6% farther than they normally would. But when the display overstated head rotation, their pain-free range of motion shrank by an average of 7%.
“While previous research has indicated that external cues can influence the intensity of pain experiences, these results are novel in showing that external cues can also shift the physical point at which pain is experienced,” Mosely states.
[Source: Association for Psychological Science]