1 Introduction Synaesthesia for pain is a recently defined condition in which patients perceive pain in one part of their bodies that is triggered when pain is observed or imagined in another person (Fitzgibbon et al 2010; Giummarra and Bradshaw 2008). When observ- ing another in pain, we not only consciously comprehend that they are in pain, but we also interpret their experience throughout some of the same regions of the pain matrix that mediate personal experience of pain (Jackson et al 2006; Singer et al 2004). The pain matrix is a network of cortical regions involved in processing pain in oneself comprising both sensory and motor regions of the cortex (Jackson et al 2005). Pain synaesthetes typically experience pain in a presensitised region öeg phantom leg or pelvis öwhen observing or thinking about another being injured or in pain, but not when they directly experience such an injury. Pain synaesthesia likely corresponds to a heightened sensitivity in pain networks in the brain. While all current published cases of synaesthesia for pain have presented it as acquired sensory disturbances (Bradshaw and Mattingley 2001; Giummarra and Bradshaw 2008), typically following trauma or injury (eg amputation or childbirth), other sensory synaesthetes report the congenital variant of touch synaesthesia (Banissy et al 2009; Ouch! My phantom leg jumps/hurts when you stab ``my'' virtual hand Perception, 2010, volume 39, pages 1396 ^ 1407 Melita J Giummarra, Bernadette M Fitzgibbonô, Nellie Georgiou-Karistianis, Michael E R Nicholls½, Stephen J Gibson#, John L Bradshaw Experimental Neuropsychology Research Unit, School of Psychology and Psychiatry, Monash University, Wellington Road, Clayton, VIC 3800, Australia (ô also Monash Alfred Psychiatry Research Centre, School of Psychology and Psychiatry, Monash University and the Alfred Hospital, Melbourne, VIC, Australia); ½ School of Psychology, Flinders University, Bedford Park, South Australia; # National Ageing Research Institute, Parkville, VIC, Australia; and Caulfield General Medical Centre, Caulfield, VIC, Australia; e-mail: melita.giummarra@monash.edu.au Received 23 September 2009, in revised form 3 September 2010 Abstract. Pain synaesthetes experience pain in a presensitised region when observing or imagining another person in pain. We conducted an upper-limb embodiment study using a modified rubber- hand illusion in which lower-limb amputees originally participated as control subjects for the upper-limb amputees. While we found all subjects experienced topographic illusory sensations, we also serendipitously found that lower-limb amputee pain synaesthetes experienced pain or a motor response in their phantom leg when the embodied hand was threatened (eg with a retract- able knife, mousetrap, or syringe) or submitted to high-frequency stimulation (eg vibration). Embodiment illusions were brought about by touching, manipulating, or threatening a rubber or real hand which was observed through a mirror so that it was superimposed upon the target hand (phantom hand for upper-limb amputees, or real hand in others). Participants included eight pain synaesthetes (six lower-limb amputees, one upper-limb amputee, and one nonamputee), and thirty-one controls (eight lower-limb amputees, twelve upper-limb amputees, and eleven non- amputees). We documented participant's subjective reports, together with quantitative measures including the Questionnaire Measure of Emotional Empathy. We found no association between pain synaesthesia and empathy scores. On the basis of related literature we suggest that pain synaesthetes likely experienced phantom-leg pain because (a) the motor system was already engaged during visual capture; (b) threatening stimuli, to which they are hyper-vigilant, triggered avoidance or `escape' motor schemata; and (c) there could be no feedback confirming that initiated motor schemata for the phantom limb were successfully performed. Ultimately, we have further defined this new condition, synaesthesia for pain, as not only having a sensory pain component, but also a key motor component, manifesting itself in avoidance, contraction, and withdrawal `actions'. doi:10.1068/p6582