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Comment by OisinMoran | Hacker News Reader

Interesting article, but I can 100% tickle my own feet. I don't understand why the fact of not being able to tickle yourself is repeated so often without being questioned.

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It has been noticed that those with schizophrenia (not saying you have that) are able to tickle themselves.

The hypothesis is that people with schizophrenia are less able to predict their internal sensations - and because tickling is so tightly coupled exciting our brains expectation and predictions - they experience it as if someone else is doing it.

My partner of a few years can do it and she couldn't be further from the representations in the literature or media (Sapolsky's lecture on it) that I've seen on schizophrenia; however, I'm not even remotely an expert in any of it.

ASD and schizophrenia share something in common: Both feature NMDA receptors functioning differently than in neurotypicals, which is a plausible cause for why some people are able to tickle themselves.

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3808979/

https://pubmed.ncbi.nlm.nih.gov/17097347/

People with either are less likely to experience illusions. SlateStarCodex had a decent article that touched on the phenomenon a few years ago:

https://slatestarcodex.com/2017/06/28/why-are-transgender-pe...

I used to be able to tickle my own feet a little bit when my skin was drier, but I can't any more. I don't have any of the symptoms in that NIH doc. Unsure if related but I also receive no effects from morphine regardless of dosage. Nobody has been able to tell me why.

The neurotypicals susceptibility to illusions is IMHO a cohesion enhancing adaptation for life in large groups.

oh damn

i can tickle myself reliably and in a bunch of diff places but pretty sure i'm otherwise normal. not a schizo not an autist so idk why... or at least pretty sure i'm not (◕‿◕)

I can tickle myself in several spots on my upper back, and I definitely don't think it feels like someone else is doing it (and don't have trouble predicting it from what I can tell, although I guess I've never been tested on that rigorously). If anything, my expectation of it causes it to be even more overwhelming (it's not something that I enjoy at all honestly regardless of whether it's me or someone else doing it; the best comparison I can make to it is like accidentally shocking yourself when brushing your finger against the metal when plugging something into an outlet, just not as strong and localized to the tickled spot).

On the other hand, I've noticed a fair number of other strange reactions that I sometimes get to sensations that I've occasionally seen other people online mention but have never met anyone else in person who also says they have them. One weird one is that when certain things vibrate in my hand (e.g. some but not all of the cell phones I've had and my Nintendo Switch's "rumble"), my inner ear will feel like it's shaking around, which is very unsettling. It seems to happen on the opposite ear of the hand my phone is being held (or both ears if both hands are touching). I can also sometimes replicate it by tickling parts of my lower face (in which case it happens on the same side as the part of my face touched), which makes me think it's due to some sort of actual physiological response to some extent rather than just some sort of weird resonance). From googling this in the past, there do seem to be other people who experience this, but I couldn't find any sort of documented research on it (presumably due to it being rare and benign enough not to merit anyone's attention).

Does that effect extend to sexual touch, e.g. masturbation? Has that ever been studied? I realize this is a strange observation.

> It has been noticed

Source?

https://pubmed.ncbi.nlm.nih.gov/28500871/

Because this is basically bullshit. The title calls it neuroscience, but they're studying classical stimulus-response, just like Wundt. Then they come up with a theory that needlessly incorporates some neuro-stuff, which then is pronounced fact. If they would have done it properly, they would have noticed that you can tickle yourself. I'm pretty ticklish, and like you, I can also tickle myself under my own feet.

I somehow remember a thing about tickling being actually two mechanisms, biologically speaking. One is the light, very superficial tickling which only makes you smile, the other is the more intense kind which is able to induce full-on laughter. And they've both have very different evolutionnary hypothesis as to why they exist in modern humans.

AFAIK, the light kind can be self-inflicted. The other can't.

I'm able to sometimes but not always. Some research have been done on the subject, with various conclusions. One I remember reading about some time ago: "Individuals with pronounced schizotypal traits are particularly successful in tickling themselves" - https://www.sciencedirect.com/science/article/abs/pii/S10538...

I'm not sure I've actually met anyone who can't tickle themselves.

Hello. Now you have

You can't tickle your feet?

Considering it’s hackernews it’s likely many here can’t touch their feet.

You don't need to touch, you can just rub them on a pointy surface, like the edge of a table.

I mean, I can perform a tickling action on my feet but no tickling sensation occurs

I can tickle my feet but I won’t laugh. To me that’s the difference. If another person tickles my feet I will laugh.

I can only tickle myself when high on about 5-10mg of THC. Any other time and it simply doesn’t work.

I can tickle myself too and do it frequently. It always surprises me though. I can’t tickle myself intentionally. I can come very close! I can get the physical sensation, but not the tickle reaction that’s involuntary.

I am very curious - when you say that, do you mean that you get that same sensation on your skin as when someone else is tickling you, possibly with a need to scratch afterwards, or do you get the full laughing and avoidance response?

I get the skin surface sensation like I’ve brushed against something soft and delicate that isn’t my own intention, but it is my own body so I realize what’s happening processing the same moment. I don’t have a laugh response or the kind of abandon I remember in childhood being tickled. It’s like a shiver or goosebumps and a mental giggle when I realize what I did to me.

The laugh response is what the aricle/researchers and everyone else means when they say "you can't tickle yourself", I'm pretty sure most people don't realize this and are, like you, referring to just the skin sensation.

> As planned, Subject 1 couldn’t help but laugh. The fact that they couldn’t help it is what has drawn Michael Brecht, leader of the research group from Humboldt University, to the neuroscience of tickling and play. It’s funny, but it’s also deeply mysterious—and understudied.

People tend to come up with a variety of words to describe just the skin sensation when challenged on this (just scroll through other responses in this thread now that they've started responding), and "tickle" just seems to be a fallback when they don't think about it.

I can tickle my feet and I can tickle the ceiling of my mouth with my tongue. It's hard to explain but if you very slowly and gently drag the tongue through the ceiling of the mouth at least for me it triggers the tickling response the most consistent and reliable way. Article is complete bullshit.

I can tickle myself anywhere, especially on my back. It feels no different than if someone else were doing it.

Does it cause you to laugh and frantically try to move away from the tickling? My understanding is that that is what most people don't experience when they try to tickle themselves.

Not laugh, but I do recoil/jerk away.

I wonder if you're more likely to tickle your feet because your feet are are the main part of your body that gets a strong touch from an external object consistently when walking. Maybe the same mechanism discussed sort of turns off or is muted for feet because of this?

Do you laugh when you do so?

I don't, even when it's other person. Actually it's a very annoying sensation, even infuriating. I don't recommend tickling me unless you want to be punched in the face.

The same for me. I have extremely ticklish feet (just as passing touch is enough), and while it’s not as bad when I tickle myself, I certainly can do it.

Do you get the laughing reaction and almost involuntary spasms to retract your feet, or just the unpleasant ticklish sensation on the skin?

I don’t usually get a laughing reaction at all from tickling, it’s more shocked gasping, but yes to the involuntary spasm and retraction.

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