When the brain is alerted of a signal that it would interpret as pain, peculiar motion patterns are set into effect - in other words, it makes us move in peculiar ways. That process allows it to localize and identify sources and localizations of pain. Then, the brain will be asserted and reassured that it has, indeed, found a proper localization or body site where it then will place the pain. From then on you will suffer pain that is assigned, by your brain, to that particular place on your body.
However, you may not want your brain to assign a place for pain.
Obviously, our brain can also be confounded and lead to conclude wrongly. Simple methods include mirror exercises for phantom pain that have the capacity to improve some people's phantom pains and make it worse for others. A more easy to understand and less error-prone method to confuse the brain is to cross one's arms in order to mess up the body's frame of reference.
Very interesting indeed.
Pain. 2011 Jun;152(6):1418-23. Epub 2011 Mar 26.
The analgesic effect of crossing the arms.
Gallace A, Torta DM, Moseley GL, Iannetti GD.
Department of Psychology, University of Milano-Bicocca, Italy.
The ability to determine precisely the location of sensory stimuli is fundamental to how we interact with the world; indeed, to our survival. Crossing the hands over the body midline impairs this ability to localize tactile stimuli. We hypothesized that crossing the arms would modulate the intensity of pain evoked by noxious stimulation of the hand. In two separate experiments, we show (1) that the intensity of both laser-evoked painful sensations and electrically-evoked nonpainful sensations were decreased when the arms were crossed over the midline, and (2) that these effects were associated with changes in the multimodal cortical processing of somatosensory information. Critically, there was no change in the somatosensory-specific cortical processing of somatosensory information. Besides studies showing relief of phantom limb pain using mirrors, this is the first evidence that impeding the processes by which the brain localises a noxious stimulus can reduce pain, and that this effect reflects modulation of multimodal neural activities. By showing that the neural mechanisms by which pain emerges from nociception represent a possible target for analgesia, we raise the possibility of novel approaches to the treatment of painful clinical conditions. Crossing the arms over the midline impairs multimodal processing of somatosensory stimuli and induces significant analgesia to noxious hand stimulation.