Somatosensory Amplification and Illusory Tactile Sensations
Date: 2012-06-19 01:30 PM – 03:00 PM
Last modified: 2012-04-25
Abstract
Experimental studies have demonstrated that it is possible to induce convincing bodily distortions in neurologically healthy individuals, through cross-modal manipulations; such as the rubber hand illusion (Botvinick & Cohen, 1998), the parchment skin illusion (Jousmaki & Hari, 1998) and the Somatic Signal Detection Task (SSDT; Lloyd, Mason, Brown, & Poliakoff, 2008). It has been shown previously with the SSDT that when a tactile stimulus is presented with a simultaneous light flash, individuals show both increased sensitivity to the tactile stimulus, and the tendency to report feeling the stimulus even when one was not presented; a tendency which varies greatly between individuals but remains constant over time within an individual (McKenzie, Poliakoff, Brown & Lloyd, 2010). Further studies into tactile stimulus discrimination using the Somatic Signal Discrimination Task (SSDiT) have also shown that a concurrent light led to a significant improvement in people’s ability to discriminate ‘weak’ tactile stimuli from ‘strong’ ones, as well as a bias towards reporting any tactile stimulus as ‘strong’ (Poliakoff, Puntis, McKenzie et al., In Prep), indicating that the light may influence both early and later stages of processing. The current study investigated whether the tendency to report higher numbers of false alarms when carrying out the SSDT is correlated with the tendency to experience higher numbers of cross-modal ‘enhancements’ of weak tactile signals (leading to classifications of ‘weak’ stimuli as strong, and ‘strong’ stimuli as ‘stronger’). Results will be discussed.
References
Botvinick M & Cohen J. (1998). Rubber hands `feel' touch that eyes see. Nature, 391: 756.
Jousmaki V & Hari R. (1998). Parchment-skin illusion: Sound-biased touch. Current Biology, 8: 190.
Lloyd DM, Mason L, Brown R J, Poliakoff E. (2008). Development of a paradigm for measuringsomatic disturbance in clinical populations with medically unexplained symptoms. Journal of Psychosomatic Research, 64: 21-24.
McKenzie KJ, Poliakoff E, Brown R & Lloyd DM. (2010). Now you feel it, now you don't: How robust is the phenomenon of illusory tactile experience? Perception, 39: 839-850.
Poliakoff E, Puntis S, McKenzie KJ, Lawrence A, Brown RJ & Lloyd DM., Vision affects the judgment of the strength of tactile events. (In Prep). Experimental Brain Research.
Jousmaki V & Hari R. (1998). Parchment-skin illusion: Sound-biased touch. Current Biology, 8: 190.
Lloyd DM, Mason L, Brown R J, Poliakoff E. (2008). Development of a paradigm for measuringsomatic disturbance in clinical populations with medically unexplained symptoms. Journal of Psychosomatic Research, 64: 21-24.
McKenzie KJ, Poliakoff E, Brown R & Lloyd DM. (2010). Now you feel it, now you don't: How robust is the phenomenon of illusory tactile experience? Perception, 39: 839-850.
Poliakoff E, Puntis S, McKenzie KJ, Lawrence A, Brown RJ & Lloyd DM., Vision affects the judgment of the strength of tactile events. (In Prep). Experimental Brain Research.