Ticklishness
Ticklishness is kind of funny.
It’s been said that sex is the only time you’re having fun but you’re not laughing. Tickling is the reverse: you’re laughing but not (always) having fun.
Tickling and ticklishness are a bit hard to pin down, but, roughly, tickling is gently touching sensitive parts of another’s body, eliciting, under at least some conditions, helpless laughter by the tickled. Yes, I am going to refer to a person who someone tickles as “the tickled.”
It should, first, be clear that there is nothing necessary about the connection between light touches and laughter. There are plenty of times and ways that we are touched lightly and have no hilarious reaction.
In addition, tickling seems… weird, almost like a cheat code. If you touch the person in these secret spots, they laugh uncontrollably and are helpless for a while. It’s the sort of thing you’d put into a game in easy mode to help players get past a boss.1 And to be clear, this cheat code is bad for the boss. It’s like a little “disable” button. Why is it there? Is it an adaptation? Byproduct? Ticklishness does appear to be functionally complex and consequential. If it’s the side-effect of something else, then why didn’t it get selected out?
Let’s follow the possibility that ticklishness is an adaptation. What’s its function? Why laugh to the point of incapacity when someone brushes that one spot under your arm or at your waist? This mystery deepens when one considers that while some tickling seems especially benign—a mother tickling her baby—some tickling seems less so, as implied by the expression “tickle torture” and this sequence in Heckle and Jeckle. Tickling causes all the signs of mirth, and some people like it, but the part where one is left vulnerable is unpleasant, and many people try hard to avoid it.
As Seinfeld would say, what is the deal with tickling?
To get this sorted in terms of what is being measured, here are some stylized facts.
It’s difficult, if not impossible, to tickle oneself.2
Tickling declines with age.3
Tickling occurs between relatives—e.g., between parents and children—and, in addition, in friendships and courtship. It’s rare between strangers.4
The areas that are ticklish include sensitive areas, such the neck and armpits, which are also vulnerable areas.5
There is, as indicated above, a dual quality to being tickled: there is something positive about it—the laughter—but also something about it that people dislike.
At its heart, the tickle is a gentle touch to a potentially vulnerable spot on the body. From a functional point of view, contact with a vulnerable spot conveys a valuable piece of information to the tickled: whoever is tickling me could harm me if they wished. At the same time, the fact that the touch does no actual, lasting harm adds another piece of information: the person doing the tickling is choosing not to hurt me.
In short, a tickle is measuring the extent to which the tickler could harm me but is choosing (for the moment) not to. I’ll refer to this as forbearance.6 Roughly, I think this is what ticklishness might be measuring: How much am I not being hurt by someone who could, in principle, do so? Forbearance carries crucial information.
Thinking about tickling as measuring forbearance helps explain the positive aspect of tickling, the laughter. It’s good news that the tickler has, at least for now, benign intent. The pleasurable aspects of being tickled might be an assay of this intent.
Ok, but why does laughing from tickling leave one so helpless? Here, as usual, the non-human animal literature is useful. Organisms can benefit from signaling submission. In the case of wolves, for example, subordinates bare their bellies to the dominant, making themselves vulnerable to the killing bite. This vulnerability signals to the dominant the subordinate’s recognition of the hierarchy. This is valuable to both the subordinate and the dominant because there is no need for further violence, which would be costly for both.
In short, the sensation of being tickled is the measurement of forbearance, signaling helplessness and, in turn, deference. The incapacitating laughter is, like the wolf case, making the tickled vulnerable, signaling deference.7 This idea helps to make sense of why ticklishness declines with age and our linguistic abilities improve—because we are increasingly able to acknowledge submission with words rather than behavior.
What about the two different aspects of tickling: the happy mother/child kind and the less happy type? To tease these apart, it might be useful to divide tickling into its benign and more sinister varieties.
I’ll call the first one learning-forbearance. In the parent/baby case, when the baby is being tickled, the baby is learning something very important about the world it has been born into: who can get very close to it and, when they do, choose not to harm it. Tickling, on this view, is measuring benign intent and picks out those people in the world who are close allies, mostly likely a parent or sibling. This is a case in which the tickled is learning forbearance-today-forbearance-tomorrow.
On the other hand, there is simultaneously a sinister side to being tickled. Someone who can get to your sensitive areas is also a potential threat.
In this context, I sometimes think about the practice—which thankfully seems to have declined—of throwing milkshakes at people that members of some group don’t like. At first glance, this seems juvenile. A milkshake? On the other hand, getting hit with a milkshake tells the target that if the person throwing it had wanted to harm them more seriously, they could have. Getting hit with a milkshake is a threat or a warning.
In some contexts, tickling seems to have this darker quality. Tickling might be used to signal that the tickler is showing forbearance…for now. Tickling could be like tossing a milkshake: it’s a signal that the tickler could do more harm, but is choosing not to. This aspect of tickling might explain why there is a sex difference in laughing in response to tickling8 and why some people dislike being tickled: it’s a demonstration of power over the tickled. Forbearance today, but not necessarily tomorrow. As moviegoers know, when a person in power or a captor places a gentle kiss on the cheek of someone who is incapacitated or otherwise powerless, this effectively conveys a dread-laden threat, even if—especially if—the kiss or touch is sensual or gentle.9
None of this is to say that tickling outside of the kin/family context is necessarily malignant. Courtship is complicated, rife with ambiguous signals.10 Could tickling in courtship be a way to test limits and increase intimacy? If A tickles B and B doesn’t recoil, might A infer that B is interested in more than just tickling? Could be.
Let’s return to our stylized facts and see how well the forbearance view accounts for these facts:
Difficult to tickle oneself: One cannot be dominant/submissive to oneself, nor can one threaten oneself.11
Ticklishness declines with age: Who can get close to you but will not harm you is especially important to learn when one is a baby and, consequently, particularly vulnerable.
Common for parent/child and courtship: Relatives use forbearance to signal ongoing forbearance. Courtship has a more ambiguous interpretation.
Sensitive areas are ticklish: The signal is most effective if the tickled knows that the tickler can access vulnerable areas.
Dual quality to being tickled: The positive aspect is the forbearance. The negative aspect is the helplessness and the potential for genuine harm.
So, in sum, the sensation of being tickled seems to measure forbearance, the extent to which the tickler could harm one but chooses not to. The response is to laugh uncontrollably, a signal that one defers or submits to the person doing the tickling.12 The reason some people like being tickled—by the right person in the right context—is that some tickling is a signal of ongoing forbearance. The reason some people hate being tickled is that tickling is, in some contexts, akin to a threat.
It should be clear that reciprocal explanations apply to the urge to tickle. For a parent, it’s a way to teach a baby that he or she is benign and can be trusted. For someone courting, it’s a strategy to test the receptivity of a potential partner to touch. For someone with darker motives, it’s a way to threaten without inflicting serious harm.
And that, in short, is—or might be—the deal with tickling.
Coda
I’d like to add a coda, more speculative than the material above. If the above analysis is correct, then there is something important and positive conveyed by forbearance. In the same way that other social cues generate some positive affect—a pat on the head, or what have you—forbearance should feel “good,” given that it conveys positive news. (Forbearance is “fitness-good” because it implies that someone else who can hurt you is choosing not to, probably because they consider you a friend or ally.) Thinking about tickling led me to wonder if forbearance in another domain might similarly partially explain submissiveness in sexual play.13 In some ways, the relationship between the dominant and submissive is an extreme case of forbearance: the dominant is in a position to do great harm while the submissive is most vulnerable. Instead, with the submissive in an especially vulnerable position, depending on the details of the play, the dominant does not seriously harm the submissive: a lot of Dom/Sub play includes the motions of harm-inducing acts without causing serious pain. For instance, the whips used in the bedroom are made from materials that don’t cause pain in the way that whips used for actual punishment would have. This parallel between tickling and BDSM leads me to wonder if this helps to explain why some people derive pleasure from playing the submissive role in sexual situations in the same way that some people, at least, like to be tickled. In some ways, it is eminently comprehensible why people derive pleasure from a context in which one is ultimately vulnerable to another who chooses to help rather than harm. Reciprocally, this explains the motive to play the role of the dominant role which, oddly, is parallel to a mother’s tickling of her baby. I leave aside here questions of individual differences in ticklishness and kinks, which seem robust.
This logic applies in other contexts at various levels of abstraction. Writers of fiction use this arc to reveal character. When the hero is vulnerable—a minor character knows an undercover agent’s true identity or the besieged protagonist’s secret past—forbearance illustrates the nobility of the “character in the know” who stays silent or, conversely, the moral crapulence of the character who reveals the damaging information, kicking them when they’re dow. The case of Victor Hugo’s Bishop in Les Misérables is one such example: the pivotal scene with the candlesticks leaves the reader awash in respect for the Bishop. Very generally, what characters—and actual people—do in the context of others’ vulnerability is extremely informative of their character, well beyond the context of tickling and sexual contexts. Forbearance merits more scholarly attention than it has received.14
References
Gersick A., & Kurzban R. (2014). Covert sexual signaling: Human flirtation and implications for other social species. Evolutionary Psychology, 12(3): 549-69.
Holvoet, L., Huys, W., Coppens, V., Seeuws, J., Goethals, K., & Morrens, M. (2017). Fifty shades of Belgian gray: The prevalence of BDSM-related fantasies and activities in the general population. The Journal of Sexual Medicine, 14(9), 1152-1159.
Lemaitre, A. L., Luyat, M., & Lafargue, G. (2016). Individuals with pronounced schizotypal traits are particularly successful in tickling themselves. Consciousness and cognition, 41, 64-71.
McCullough, M. E., Fincham, F. D., & Tsang, J. A. (2003). Forgiveness, forbearance, and time: the temporal unfolding of transgression-related interpersonal motivations. Journal of personality and social psychology, 84(3), 540.
Proelss, S., Ishiyama, S., Maier, E., Schultze-Kraft, M., & Brecht, M. (2022). The human tickle response and mechanisms of self-tickle suppression. Philosophical Transactions of the Royal Society B, 377(1863).
Provine, R. R. (2004). Laughing, tickling, and the evolution of speech and self. Current Directions in Psychological Science, 13(6), 215-218.
Renaud, C. A., & Byers, E. S. (1999). Exploring the frequency, diversity, and content of university students' positive and negative sexual cognitions. The Canadian Journal of Human Sexuality, 8(1), 17-17.
Svebak, S. (2021). The importance of skin area and gender in ticklishness. Scandinavian Journal of Psychology, 62(5), 683-688.
In Larry Niven’s “known space” books, including Ringworld, there is a weapon called a tasp, which “jolts the pleasure center of the brain,” causing the target to experience an orgasm so powerful that the “victim” writhes on the ground, incapacitated with ecstasy. The tasp is, functionally, a sexual tickle on steroids.
See Proelss et al. (2022). The New York Times ran a story about this. Alan Fridlund suggested this was because “ticklish laughter is social,” which is consistent with—though much less specific than—the suggestion here. It is also potentially interesting to note that there is evidence that people with the traits typical of schizophrenia can, indeed, tickle themselves (Lemaitre et al., 2016).
“…the frequency of tickle frolics declines precipitously (about 10-fold!) after the age of 40…” Provine (2004).
“…people tickle and are tickled overwhelmingly by friends, family, and lovers…” Provine (2004), p. 217.
Proelss et al. (2022).
I can’t think of a better English word for this idea. I am open to the possibility that there is one.
Svebak (2021): “…females appeared more often than males to respond overtly with laughter…” p. 687.
Gersick and Kurzban (2014).
See Provine (2004).
The prevalence of interest in BDSM is substantial, as high as 50% or more in some samples (Holvoeta et al., 2017; Renaud & Byers, 1999).
But see, e.g., McCullough et al., 2003.