Mirror-touch synaesthesia: the role of shared ... - UCL Discovery

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Chapter 9
2 also indicate a number of features linked to the characteristics of the condition. The
findings from experiment 2 indicate that the inducer for synaesthetic experience is not
linked to spatial cueing, but is related to bodily touch (and in some cases touch to
objects). The findings also indicate the specular subtype is the more common frame
of reference adopted by mirror-touch synaesthetes and the relative frequencies
(approximately 81% show a specular frame of reference) are similar to those reported
in studies investigating the preferred spatial frame adopted when imitating another’s
behaviour - both adults and children tend to imitate in a specular mode (Schofield,
1976; Franz, Ford and Werner, 2007). Further characteristics indicate commonalities
between mirror-touch synaesthesia and other variants of synaesthesia. For example, a
general characteristic of synaesthesia is that different variants of synaesthesia tend to
co-occur (Simner et al., 2006). This also appears to be the case in mirror-touch
synaesthesia. Synaesthetic experiences also tend to be consistent over time (Baron-
Cohen, Wyke, and Binnie, 1987) and the mirror-touch synaesthete’s spatial sub-type
(i.e. whether they belong to the specular or anatomical category) appears to be
consistent across time (Chapter 2) and across different body parts (Banissy and Ward,
2007).
While these findings indicate that mirror-touch synaesthesia shares common
ground with other types of synaesthesia, possible similarities in the neural basis of the
condition are less apparent. A point of dispute in the synaesthesia literature is
whether synaesthetic experience is due to cross-activation between brain regions
(either through increased structural connectivity or malfunctions in cortical inhibition)
or disinhibition of the same cortical networks found in non-synaesthetes (Bargary and
Mitchell, 2008; Cohen Kadosh, Henik, Catena, Walsh, and Fuetnes, 2009; Cohen
Kadosh and Walsh, 2008; Grossenbacher and Lovelace, 2001; Hubbard and