Here is the closest correlation I could find for current information on the subject. Is there more somewhere?
2007 Conference: Provisional programme and abstracts
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Mirror-Touch Synaesthesia and Empathy
Michael J Banissy and Jamie Ward
Department of Psychology, University College London, London, WC1E 6BT, UK
Previous studies have indicated evidence of a tactile mirror-system in which actual and observed touch results in activity in similar areas of primary and secondary somatosensory cortices. For some people, with ‘mirror touch’ synaesthesia, this can produce a felt tactile sensation on the observer’s body (Blakemore et al, 2005). Using a new behavioural paradigm we provide evidence for the authenticity of this form of synaesthesia and show that mirror touch synaesthetes score higher on measures of empathy. Participants were requested to detect the site of actual touch while ignoring observed touch (and the synaesthetic touch induced from it). Consistent with self-reports, mirror touch synaesthetes were significantly faster at identifying a site touched on their own body when observed touch to another person was congruent with their synaesthetic experiences compared to incongruent trials. Furthermore, mirror touch synaesthetes showed heightened scores on the emotional reactivity subscale of the empathy quotient compared to controls. These findings are consistent with the notion that we empathise with others through a process of simulation.
Blakemore, S. J., Bristow, D., Bird, G., Frith, C., & Ward, J. (2005). Somatosensory activations during the observation of touch and a case of vision-touch synaesthesia. Brain, 128, 1571-1583.
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http://www.uksynaesthesia.com/