Is experiencing ticklish sensations the same as being tickled?

Angus James McLachlan, George Van Doorn

Abstract


Aristotle was one of the first to note our inability to tickle ourselves, a phenomenon that has been discussed frequently over the years. More recently, cognitive and neuropsychologists have offered physiological accounts of this inability relying, in some cases, on rather ingenious experimental techniques. Van Doorn, Hohwy, and Symmons (2014) deployed the body transfer illusion and the related rubber-hand illusion to disentangle two competing hypotheses that attempted to explain why we can’t tickle ourselves. The first hypothesis contended that when people tickle themselves, a precise copy of the motor command to the muscles leads to attenuation of the sensory input from a ‘tickle’, and hence an inability to tickle ourselves. However, Van Doorn et al. found that attenuation was the product of a more general notion of agency. In lay terms, as long as participants ‘knew’ they controlled their own actions, the sensations were significantly less ticklish than when the tickle was known to have been produced by someone else. Although this form of cognitive explanation is almost certainly adequate to account for percepts elicited by light touches to the skin, as occurred in this experiment, it may not be sufficient to account for the full experience of being tickled, as it is understood in everyday terms. For example, some would argue that the pleasure of being tickled, and the enjoyment associated with tickling someone else, cannot be understood without reference to the relationship that exists between tickler and tickled. As Darwin noted, babies tickled by a stranger may derive little pleasure from the same sensations that would cause considerable mirth if produced by a trusted other. At the other end of the tickling spectrum, it is quite possible to induce considerable laughter in children who anticipate, but are not actually, tickled. It seems as though cognitive accounts of tickling should be expanded to recognise that the experience of being tickled does not rely solely on knowing who is generating the sensation, but seems to require an understanding of the tickler’s intent. In a complementary fashion, one might wish to draw a clearer distinction between ticklish sensations and the perception of being tickled. Here, we intend to explore these issues.


References


Van Doorn, G, Hohwy, J., & Symmons, M. (2014). Can you tickle yourself if you swap bodies with someone else? Consciousness and Cognition, 23, 1-11.