Emma L Broglia

We present the first study to examine indicators of autonomic arousal associated with shifts in body image and as a function of predisposition to report spontaneous anomalous bodily experiences (ABEs) from nonclinical samples. Participants completed the Temporal-Lobe Experience subscale of the Cardiff Anomalous Perception scale-a measure associated with anomalous experiences resulting from temporal lobe dysfunction (Bell, Halligan, & Ellis, 2006) followed by a rubber-hand illusion experiment. We examined: (a) the time taken to induce the illusion, (b) effects on the tonic skin conductance level, and (c) phasic skin conductance responses in the form of nonspecific skin conductance responses (NS-SCRs) in the period leading up to the declaration of the illusion. The illusion took significantly longer to induce in those reporting high levels of ABEs, relative to those reporting low levels of such experiences. A significant increase in the tonic skin conductance level and the frequency of NS-SCRs occurred in the period leading directly up to the declaration of the illusion. Both measures were significantly increased for those reporting higher-levels of ABEs. The data question generic notions of "weak" body representations subserving increasing malleability in body image. Instead, they lend general support for a "dysconnection" account of anomalous bodily experiences-at least for some nonclinical hallucinators. Theoretical considerations are discussed.

Recent findings from studies of epileptic patients and schizotypes have suggested that disruptions in multi-sensory integration processes may underlie a predisposition to report out-of-body experiences (OBEs: Blanke et al., 2004; Mohr et al., 2006). It has been argued that these disruptions lead to a breakdown in own-body processing and embodiment. Here we present two studies which provide the first investigation of predisposition to OBEs in the normal population as measured primarily by the recently devised Cardiff anomalous perception scale (CAPS; Bell et al., 2006). The Launay-Slade Hallucination scale (LSHS) was also employed to provide a measure of general hallucination proneness. In Study 1, 63 University students participated in the study, 17 of whom (26%) claimed to have experienced at least one OBE in their lifetime. OBEers reported significantly more perceptually anomalies (elevated CAPS scores) but these were primarily associated with specific measures of temporal-lobe instability and body-distortion processing. Study 2 demonstrated that OBEers and those scoring high on measures of temporal-lobe instability/body-distortion processing were significantly impaired, relative to controls, at a task requiring mental own-body transformations (OBTs) (Blanke et al., 2005). These results extend the findings from epileptic patient studies to the psychologically normal population and are consistent with there being a disruption in temporal-lobe and body-based processing underlying OBE-type experiences.