The Ten Fingers of Dr. H.

By Mark Wheeler|Monday, September 01, 1997
Adults rule. Because we rule, we get to do mischievous things to our kids. Like tickling them. It’s one of life’s small pleasures to sneak up behind a guileless child, tackle him or her to the ground in an affectionate, roughhouse, big-lug kind of way, then attack armpits, ribs, or neck with wiggly fingers.

The little moppets just love it, too. When I pounce on my son or nephews, they howl in laughter. They curl into a fetal position. They beg me to stop.

Turns out they aren’t kidding. They really want me to stop. At least that’s the conclusion Christine Harris, a Ph.D. candidate in social psychology at the University of California at San Diego, has come to after conducting two studies on tickle. (Not, please note, tickling. Dropping the suffix, I think we can all agree, gives the topic of tickle a more serious air, one more worthy of scientific scrutiny.) Laughter and tickle indeed go together, says Harris, but not because people enjoy the activity. It appears that people’s hee-hawing reaction to tickle is a reflex, just like the one produced when a ball-peen hammer strikes the knee. Which means that I, a big bully, was inflicting what she calls tickle torture on these kids.

Oh dear.

Harris developed an interest in the science of tickle while hanging out one day doing what all good graduate students do, reading Charles Darwin’s The Expression of the Emotions in Man and Animals. In this book, published in 1872, 13 years after the Origin of Species, Darwin speculated that all tickling is social, and he noted the similarities between humorous laughter and ticklish laughter. For example, with both one must have a happy state of mind. In addition to laughter, there are other shared physical reactions, like that convulsive, herky-jerky body motion we’ve all experienced while laughing. Piloerection is also common (which is not what you think, guys, but another reflex, this time of the sympathetic nervous system): in humans it appears as goose bumps; in other, furrier animals, such as angry dogs, it’s what happens when their hackles--the hairs along the back of the neck--rise.

Finally, says Darwin, a common element of surprise is necessary-- an unexpected punch line from a joke, say, or a blindside tackle leading to a tickle.

Darwin suggested that if a child was tickled by a stranger, she’d scream in fear rather than in laughter, says Harris, and that struck me as odd. I can remember being held down by my cousins and being tickle-tortured as a kid. And if my memory holds correctly, I was still laughing, but I hated it. So the very fact that kids can be tickle-tortured against their will and still laugh made me think something else might be going on.

Harris then checked the research and found that few studies--less than a dozen--have been done on tickle. So, curious to know more, she designed a couple. Now, had I asked, I’m sure Harris would have been the first to admit that the results of her research on tickle are not going to change the world. And there’s always going to be some joyless toad who thinks there is more important work researchers should spend their time on, like finding a cure for male pattern baldness or explaining why all people past the age of 35 drool while they sleep.

I have had different reactions, admits Harris. Sometimes I get the feeling that other academics feel it’s not serious enough. Which may be one reason so few studies have been done. I’ve wondered if, in studying positive emotions like humor or laughter, there isn’t prejudice against those because they somehow don’t seem serious, even though they’re a part of our everyday lives. But if you study anxiety or fear, those are considered more serious.

Possible happy bias aside, another probable reason so few tickle studies have been done is that you must physically put your hands on someone to do the research, potentially an undignified and distasteful prospect, given the continuum that exists among the general populace regarding a rigorous adherence to hygiene. Still, in her first study, Harris had her research assistants do just that. She decided to use hands- on research to confront Darwin by examining the warm-up effect. This is a common strategy used by successful but not especially funny comedians to ensure they are always perceived as funny and thus remain successful. Before they go onstage, one or two other comedians who really are funny are sent out to warm up the audience. The idea is that once you get the audience laughing, they’ll be giddy enough--primed--to laugh at anyone, even if it’s Gallagher or Howie Mandel.

If humor and tickle are really two variants of the same thing, Harris figured, then the warm-up effect should apply to both--that is, one should enhance the other. So if you’re tickled before watching a comedy, you should laugh more at the comedy, says Harris, and if you watch a comedy before you’re tickled, you should laugh more when you’re tickled.

So Harris corralled 72 undergraduates and divided them into three groups. One group was tickled first, then shown videos of stand-up comics, including Bill Cosby; clips from funny tv shows, like Monty Python; and a video called The Best of Saturday Night Live (presumably culled from old shows that were actually funny). Another group of students watched the same clips first, then were tickled. The third, control group spent 13 sobering minutes watching a nature video on animal biomechanics (Here we see that the tendons in the jaw of the salivating hyena provide the thrust that allows it to crush the face of the helpless baby springbok), then they too were tickled pink.

Each time, the subjects were seated, with the ticklers standing nearby. The subjects were warned that the tickling would begin and were then tickled on the ribs and armpits or the feet three times for ten seconds. Unless, that is, they tried to slink down out of the chair, in which case they were not pursued.

The results, published this year in the journal Cognition and Emotion, were clear: neither the pre- nor post-tickle group laughed any harder at the comedy clips or while being tickled. (The nature-watching control group was simply nauseated.) That suggested that the priming effect was not present. If Harris is right, then no link exists between humor and tickling, and Darwin should have stopped while he was ahead.

While this was a serious research study, ultimately peer-reviewed by an academic journal, didn’t Harris feel just a little, well, stupid to be doing the tickle to a stranger? Looking back now, she says, it was a rather bizarre experiment, but at the time we really got into it.

It’s awkward to be the tickler, because you have to overcome this violation of a person’s personal space. So it became a point of pride with my research assistants to get over that. It took some training--we actually had to tickle each other to get used to it. Tickle training. Enough said.

The implications of the research, though, are fascinating. If tickle is indeed a reflex response, then someone who is naturally ticklish should be putty in the hands of a tickler no matter what the particular social situation. To double-check this reflex theory, I tried my hand at surprise-tickling a few strangers at my local mall. Interestingly, while all of them squirmed (some, in fact, quite violently), not one laughed.

Once I posted bail, I asked Harris about this seeming anomaly. Adults do get better at suppressing the reflex to laugh, says Harris, so I’m not claiming it can’t be modified. Also, I shouldn’t make too strong a claim after just my studies, especially when there’s no other empirical work on it. Tell that to my judge.

The results of her first study motivated Harris to design a second. Or maybe she just wanted to stick it to Darwin again. This time she used 33 hapless new volunteers. To make sure no social interaction was involved, she built a mechanical tickle machine, complete with a robotic hand and wiggling fingers.

If you think about it, a tickle machine is a natural progression from the first study, explains Harris. For example, it’s odd that you can’t tickle yourself. That’s one reason people have suggested that tickle requires another person--a social situation. If that’s correct, that may be why you can’t tickle yourself.

Which is a damn shame, too. After all, if it didn’t take two to tickle, life might just be less stressful. Depressed? Rub a few fingers along the rib cage and get over it. Spouse take a hike? Slip off that sneaker and stroke a little sole. It is odd, though, that we can’t self- tickle. We can scratch ourselves, certainly, and some researchers have suggested that the difference between a tickle and a scratch is only the amount of force we apply. But use nearly the same motion--the wiggle of fingers on skin--to garner a guffaw, and it’s a no go. (Maybe it’s just as well. After all, it might be a bit off-putting if in the middle of a dull meeting at work someone suddenly broke into spasmodic contortions from diddling his or her own armpit.)

The tickle machine allowed Harris to challenge the assumption that another person is required in order to elicit a laugh response from tickle. Because if you have people believing a machine is tickling them with no human around, she says, then they shouldn’t laugh.

So Harris manipulated the social situation, as she puts it. This time each person was seated in a cold and sterile lablike room. Every subject was blindfolded, given earplugs, and each right leg, foot bared, was strapped down. (Is it me, or does one wonder why the hell anyone would volunteer for this sort of thing?) Next they were told they would be tickled on the foot by a human--Harris herself--then by the tickle machine, each time for five seconds.

To make the machine, Harris brainstormed with her research assistants, then cobbled together one serious-looking piece of equipment. It included a number of computer parts, various dials, knobs, and lights, a power cord plugged into the wall, and, inside, a machine called a nebulizer, which, while it helps asthmatics breathe, also makes an important-sounding vibrating noise. The coup de grâce was the robotic hand that Harris picked up at her local Toys R Us, which attached to the machine with a hose.

The idea was to make it look believable, says Harris. The less it looked like a human--to remove any semblance of a social setting--the better.

And, yes, the machine was as phony as a politician’s heartfelt concern. The actual tickling was performed by an undergraduate--one Meg Notman--who was enrolled in what the University of California calls a 199, a course intended to give some hands-on experience in what’s involved in conducting real-world research at a major university.

Notman’s service was above and beyond the call of a 199. First she helped build the sham machine (Harris called it the Mechanical Meg). Then, before the subject entered the room, a stealth Notman would crawl under the cloth-covered table next to the tickle machine and hide, like some kid in a hide-and-seek game. At the appropriate time she would stick her hand out to perform the cootchy-cootchy-coo on the ticklee.

I wanted to talk to Notman to see if she thought scientific research was all that it was cracked up to be, but Harris hasn’t been able to find her since the conclusion of the experiment. (Chances are she’s moved as far from any research university as she can get.) Left unanswered, then, are my questions--such as, did she feel silly hiding under a table? Was it displeasing to have to tickle the fleshly underpad of a stranger’s bared appendage? San Diego has a warm climate--did she ever have to tickle with one hand while spraying Odor Eater with the other?

Notman actually did the tickle both times, whether the subject thought it was Harris or the machine (to remove any aspect of a social situation, Harris left the room when the machine was supposed to be doing the tickling). It was key for Meg to do both tickles, says Harris, otherwise there could be some difference in the stimulation. If we had a real machine and a person and we didn’t get the subjects laughing or smiling, you would never know if it was because the tactile stimulation was different or if it was because their perception of who was doing it differed.

The point is, though, that the results supported Harris’s first study, namely, that a social situation was not necessary to make people laugh, once again refuting Darwin. Sorry, Charlie. People smiled and laughed just as often in response to the machine as to the experimenter, says Harris, and she is convinced the subjects really believed they were being tickled by a machine. The reports they filled out afterward included comments like the machine felt clammy, or they could tell it felt programmed. But they still laughed or smiled.

Harris hopes her research will offer insight into other human emotions. Any behavior that people wonder about is worth investigating, she says. Once you have some understanding, you don’t know where it might lead, or how it might enlighten you in other ways.

What about tickling among the nonhuman? Young chimps appear to tickle one another during play, says Harris, and they make a chortling sound that resembles human laughter. And if you think Harris’s work is cutting edge, or even fringe, it’s worth noting that other researchers have proved that tickling cuts not only across species but kingdoms. Take, for example, Gail Taylor, a plant biologist at the School of Biological Sciences at the University of Sussex in England.

Taylor tickles plants. While they don’t giggle in response, they do respond. She’s found that plants react in predictable ways. For example, regularly stroking a plant on its stalk stunts its vertical growth yet makes the stalk grow thicker. You don’t need to talk to them, either.

The phenomenon is actually well known; it’s called thigmomorphogenesis and according to Taylor was originally proposed by Theophrastus, a pupil of Aristotle’s, way back in the third century b.c. Plants don’t have nervous systems like animals, says Taylor, but physical stimuli affect their enzymes, which act as catalysts in the plants’ development.

Touching the stem, says Taylor, causes calcium to move into the cells, which switches on and off the genes that control the enzymes that allow the plant to grow. We might assume that ‘touched’ or ‘tickled’ plants are similar to those exposed to extremely windy environments, she says. For example, trees on a cliffside--they are also stunted in growth, but most important, they are alive. So thigmomorphogenesis may enable plants to survive stressful environments.

No one knows why we humans are ticklish. There are theories--one suggests that it strengthens the bond between a mother and baby. Then there’s a small group that sees erotic overtones to tickling, but I’ve led a sheltered life and that’s not a road I’m going down. Instead I’m curious to know what other living things may be tickle-prone. Having made my son miserable, perhaps I’ll try to tickle the family cat. With the right touch, maybe it’ll achieve piloerection.
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