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

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Results and Discussion
Chapter 2
The results are summarised in Figure 2.4. Reaction times and error rates were
measured. Reaction time data were filtered prior to analysis (± 3 s.d. and all errors
removed). A 2 (Group) x 2 (Congruency) ANOVA conducted on reaction times
revealed no significant main effects or interactions (p = > .05 in all cases; Figure
2.4a). Although the direction of the effect was the same as in Experiment 1 the effect
was not significant. Analysis of the percentage of error types made by participants on
human trials also revealed no significant main effects or interactions (p = > .05 in all
cases; Figure 2.4b). Similarly, no significant differences were observed on control
trials (Figure 2.4c, d). These findings are unlikely to be due to the fact that the flash
of light is less salient than the hand, because the synaesthetes also failed to show an
effect in Experiment 1 when a hand was used on a non-human object.
To further validate that the performance of mirror-touch synaesthetes
significantly differed between experiment 1 and 2 a within-group comparison on the
size of congruency effect (incongruent minus congruent trial reaction time) shown by
synaesthetes across each task was conducted. This revealed that synaesthetes showed
a significantly greater effect of congruency on trials involving observed touch to a
human face in experiment 1 (mean ± s.e.m = 208.24 ± 52.32 msec) compared to a
flash of light shown on a human face in experiment 2 (mean ± s.e.m = 51.49 ± 34.18
msec), [t(9) = 2.98, p = < .02]. Thus the findings from Experiment 1 are related
specifically to ‘observed bodily touch’ and cannot be attributed to somatotopic
cueing.