Haptic perception and synaesthesia

Synaesthesia involving haptic perception has been less well documented than other forms of synaesthesia. There are several possibilities why this might be. Firstly, it may well be less common than other types of synaesthesia. Day [1] reports that only 4.0% of synaesthetes report coloured touch and 0.8% report vision-to-touch, compared to 68.8% reporting coloured graphemes (note: these are percentages of synaesthetes, not percentages of general population). A second reason is that researchers don't always volunteer it. We made a chance discovery of someone who experiences tactile sensations on her own body when watching someone else being touched as a result of an email request about other forms of synaesthesia. We have since found that other synaesthetes have it too but they didn't report it until prompted because they considered it 'normal' (i.e., they assumed everyone else had it).