Prosthetic limbs need not look like real ones | Hacker News Reader

Prosthetic limbs need not look like real ones

economist.com

48 pointssohkamyung52 comments

While they need not, you will often want that. Humans will naturally shy away from someone who doesn't look 'normal' (a term I didn't define). I often catch myself doing this even though all evidence says the other person is fine despite missing limbs.

hmm there is the uncanny valley phenomenon

Yeah I've seen some artificial limbs that have a cyborg-ish look to them. I'm aware that not everyone will want to go for something like that, but at least it doesn't give off the uncanny valley vibe.

Sort of. We certainly seem to have adapted rather rapidly to an ever-increasing variety of hairstyles, clothes, tattoos, piercings and accessories. We'd probably all "shy away" from the average goth or punk rock kid if it was 1940. But who still scoffs at those extreme looks these days when they serve you coffee or stop you on the street for directions?

> But who still scoffs at those extreme looks these days when they serve you coffee or stop you on the street for directions?

Lots of people, depending on how extreme.

Depends on where you live and which people you will be hanging out with that day (you can have multiple limbs - see this talk where Aimee Mullins shows off her 12 pairs of legs and discusses the context for each [1]. Limbs for Olympic running already don’t look “normal.”)

I’m queer and trans and I live in Oakland and I hang out with almost all queer anarchist people. You can bet I’d wear a tentacle from time to time and they’d all think it’s rad as hell. I’m a robotics engineer and I tend to like to be a bit loud at times and go against the grain. If I lost a hand or an arm I’d almost certainly build myself a fire shooting tentacle. (I could do this now but motivation goes up if I’ve lost a limb and I’ve begun working on replacements.)

I learned long ago that trying to appease the normative views of others simply isn’t going to work for me, so I trained away the part of my brain that worries what other people think as long as I’m not actively harming others. In doing so I’ve found a lot of people that appreciate this, and I’ve learned the value in leaning into it and building community with the weirdos.

If I’m going to my normie friend’s wedding I might bring a normal prosthetic and keep the fire shooting tentacle in the car for all the nerds that want to see it after the ceremony.

[1] https://youtu.be/JQ0iMulicgg?si=kPDy_VcRtJbQPuCb

Also the attitude matters a lot. If it comes from creativity, joy, fun, etc., it will work way better than if it comes with distanciation, opposition and awkwardness.

Context is important, but what you bring as well.

I have friends that can make a new pair of glasses uneasy, and some that can rock devils horns on a tuesday.

Yeah. I certainly understand that losing a limb is a big deal emotionally and many will not want to stand out. However as someone who has been interested in robotics since I was 11 years old my plan has always been that if I lose a limb I will build my own replacement. That gives me a lot of clarity on how I would proceed after the initial grieving and acceptance period.

Sentiment probably shifting with cyberpunk media. If I see cool prosthetics I probably couldn't resist to stare, which is also annoying I imagine.

Our limbs evolved to be efficient for life on earth.

Then we built all this artificial stuff and designed it to be as optimal as possible for human hands.

So intentionally making prosthetics really different from the human norm might make things less convenient for the wearer.

That's something only someone who has never played N64 could say.

One of the examples is an extra thumb. That prosthetic is clearly meant to be available for able-armed people.

This is very hypothetical, but if a prosthetic becomes a tool rather than a replacement for organics, then it's possible that products will change to be compatible with the tool.

Coffee cups probably won't change, but power tools might, if there's something about having an extra thumb that makes them easier to operate. My cordless drills can go from forward to reverse by moving my thumb twice, but other transitions require more repositioning of the hands. You could move the torque controller to be reached by the extra thumb, for instance, reducing the steps to countersink a wood screw.

Similarly, this issue occurs with your eyes. When you wear a vision pro you can see flicker issues with tons of displays that were designed to be visible by people and not machines.

>Our limbs evolved to be efficient for life on earth.

Eh, then why don't most other mammals have digital hands (having 10 fingers that is) like humans?

It may be better to say that human society and products are developed around us fingers, but there may very well be specialist jobs that allow prosthetics to be more efficient.

this is a common advantage of primates

Until recently, hearing aids were almost exclusively available in "skin tone" colours that didn't particularly match anyone's skin. Now all of the major manufacturers offer hearing aids in a range of consumer electronic-like metallic and gloss colours; this is especially true for hearing aids for children. There's a major generational shift, driven partly by changing social attitudes to disability but also because people are just much more used to seeing people with electronic things in their ears. A new generation of hearing aid users see their hearing aids as a gadget rather than a medical device; the choice to wear a "discreet" hearing aid is increasingly seen as a symptom of internalised stigma.

The same thing is happening with prosthetic limbs, driven to a very large extent by parasports. We're increasingly used to seeing prosthetic limbs that were designed purely for performance, where form follows function. Prosthetists used to assume that everyone would want the most "normal-looking" prosthetic limb, but that's no longer a safe assumption; to many younger people with missing limbs, the thought of wearing a prosthetic designed to mimic a natural limb is actively repellent. They're much more comfortable wearing something made of raw carbon fibre than something covered in beige rubber.

And the world of Cyberpunk and Shadowrun has officially started now.

if the "normal looking" thing doesn't look very good there's not much point bothering.

this is like how it took a few decades for us to get "nude" undergarments matching certain skin pigments in the United States.

I got mine in white! I Love it, and wish I had color options as a kid.

Probably had more to do with the fact that all the cool kids are supporting air pods or something. So now a skin tone hearing aid looks like a hearing aid. While anything else looks like a cool air pod.

> the choice to wear a "discreet" hearing aid is increasingly seen as a symptom of internalised stigma.

This tendency seems strange to me. It's a thing in disabled communities, but neurodivergent and LGBT communities as well. Not all of us view our autism as some kind of superpower, or want to "reclaim" words that were used to degrade us for decades. Similarly, some people may just want to avoid being stared at, hence the discrete prosthetics.

The subject of this article has a woman with a tentacle arm front and center. Some of the others are more human+ or human-adjacent. An extra thumb will get looks and be a conversation piece.

The tentacle is a little too deep into the uncanny valley.

seems like a limb trying to look human but ending up creepy is in the uncanny valley. A non-human tentacle limb is simply that, its not mimicking human like characteristics in a slightly off way.

In a sleeve, in a glove, or with a matched silicone cover, you'd have a hard time telling.

I think an argument is it's better to be completely different than close but not close enough. As in uncanny valley.

If it can't actually be a perfect human arm, it's better to have a clearly not-even-trying robot arm.

It probably has several different roots.

Two at least are:

One is the uncanny valley, which has to do with fitness for reproduction and avoiding disease etc. I'm talking at the animal brain level. Any animal will avoid a deformed version of itself. A human will be revolted by another human who's appearance is barely any different from their own, seen from an outside perspective like an alien, but they will love a dog to pieces, even though the dog looks infinitely more different than the human with a slightly too big forehead or something.

Another element I think is probably based on deception. If you can do a perfect fake, then ok, but if it's only close, then at both subconscious and conscious levels you don't like being deceived, because that is manipulation, someone else taking control that you didn't voluntarily give them. A steel pipe arm does not deceive, or more importantly does not attempt to deceive anyone. It ends up being as emotionlly neutral as the same person holding any other tool. Instead of holding a hammer with their hand, they are holding an arm with their shoulder.

compare https://en.wikipedia.org/wiki/Krukenberg_procedure

i remember talking to a former colleague who wrote a game to let people train to control their prosthetic arm at home. I asked him what the most wished for feature / most asked question for this prosthetic arm was and he told me that the most asked for question was if (mostly female) users could put nail polish on its "nails".

Anecdata, but I assume most users just want to have a life-like replacement.

Pockets are power.

If I have an artificial limb, I'd like to have more storage space. Human bodies try to keep crevices to a minimum since they are points of attack by pathogens and parasites. An artificial limb doesn't have to survive to see my grandkids.

There's also no reason a prosthetic limb has to constrain itself to human standard dimensions. Oh I'm sure for propriety and interpersonal dynamics they need a default mode that looks quite similar, but an arm could telescope to give you a few extra inches of reach.

And I've already seen science fiction where a prosthetic hand has nine, ten fingers instead of 5, to facilitate human computer interaction. Though one does wonder, if the brain is capable of controlling a machine hand with higher numbers of digits, can we not skip over the two middle steps in brain-computer-input-computer translation and simply imagine you're typing on a 150 key keyboard that isn't really there? Or at least switch to a virtual hand that the computer uses to intercept the motor commands to the physical hand.

> can we not skip over the two middle steps in brain-computer-input-computer translation

Well, if we're talking Ghost in the Shell (the most iconic case of robot-hand super-typing I can think of), having that disconnect is entirely on purpose, to airgap the operators' brains (enhanced, but self-contained) from any external connections.

I've seen it elsewhere but it's also possible those other cases were an homage to GitS.

I think there's still an airgap if the human brain is not feeding to or reading directly from the external computer. To be clear, we are both treating the prosthetic as 'me' in this exercise, and the system we are communicating with as Other, which we cannot implicitly trust.

The brain-hand interface could act as an input device, then you can still use your motor cortex to tell the hand to type a SHIFT-a, and the interface interprets it directly as an A instead of the movement for A. You can airgap an output device and still use it. There are some precedents for that in avionics I'm told, which are the moral equivalent of optical isolators meant to keep power spikes from frying the more delicate parts of an electrical circuit.

Which I agree is a hell of a lot safer than directly telling your brain you see a virtual terminal, and that now is a good time to have a seizure.

You want to keep heavy stuff close to the centre of mass. Heavy stuff flailing around isn't that good to keep balance and do precise movements.

My arm is full of oxygen delivery and self-repair equipment. It also contains several parts of my immune system.

A prosthetic arm within my lifetime will likely be lighter than my real one. Carrying around a flashlight or a multi tool embedded in a void in it wouldn't be that weird, and wouldn't upset your balance.

Those running legs are already much lighter, but they don't fulfill the full range of features provided by a lower leg.

> If I have an artificial limb, I'd like to have more storage space.

Importantly, the internal parts of your arm don't move around and don't change. Unlike stuff stored in a box.

Interestingly the one amputee I know well enough to speak about this with is quite aggrieved by prosthetic design decisions being made based on what someone assumes amputees need or want. The final fitting and tuning is very custom but the functional tradeoffs of the device are decided well before that, seemingly without much collaboration with the people who will ultimately use them.

If I had fake feet I wouldn't mind if they could hover

Both feet firmly planted in mid air.

Related: A 2009 TED Talk called "My 12 pairs of legs"

https://www.ted.com/talks/aimee_mullins_my_12_pairs_of_legs

https://archive.today/Xy6ax

Maybe they "should", but really, when I lose an arm or a leg, I kinda want it to look like Ian Davis' mechanical hand prosthetic!

https://www.youtube.com/watch?v=7VGgq1FjrCQ

If a prosthetic’s appearance is at best something in the uncanny valley, I think if I ever needed one then I’d prefer a design from Philippe Starck or Richard Rogers, or perhaps Jony Ive.

Give me the Deus Ex or Cyberpunk 2020 look, honestly.

depending, on the degree of assimilation the amputee has for the prosthetic, there are opportunities, such as augmentation. one may have a number of shells, or skins, and serve to generate power or mounting for wearable tech.

How do amputees feel about this?

Amputee here.

I see a lot of uninformed comments and completely idiotic ideas in this comment section, from people who are thinking they are very smart for coming up with things. Well nobody does it probably for a reason.

First of all prosthetics are expensive as fuck, so a normal person can't have 5 of them.

Secondly they are big, so unless you go around in a van you can't really say "oh I need that other one now"… the one you have on you is all.

Then the looks. They don't have to look realistic but many people will want them to. I've met a few people in wheelchair that have absolutely no use for a prosthetic and yet use one, because it pains them to see themselves without… so i can't imagine how a robocop leg would work for that issue. Also, padding and stuff has the function of protecting the important bits that are inside.

I do agree that there is no point in making them look over realistic if the wearer isn't interested in doing that, and in trying to simulate a real limb at the cost of pain, and reduced time when they can be used.

In the end what nobody realizes is that prosthetics are complete shit. Try typing on a keyboard or playing guitar for several hours with 50cm sticks tied to your fingers and see how that works out, both in efficacy and strain to your fingers. A prosthetic is more or less something like that. Please stop confusing sci-fi films with reality.

It is rather annoying having people come up to you and ask: "why don't you have a 3 million dollar prosthetics that does this and that?"… Well I don't have 3 million dollars and the thing you're thinking of doesn't exist anyway.

Thank you for this perspective.

> In the end what nobody realizes is that prosthetics are complete shit. Try typing on a keyboard or playing guitar for several hours with 50cm sticks tied to your fingers and see how that works out, both in efficacy and strain to your fingers. A prosthetic is more or less something like that. Please stop confusing sci-fi films with reality.

I'm toothless and this right here is why I never wear my dentures, and I especially don't eat with them in.

They're uncomfortable, they're made out of this soft plastic that can't rip through food the way real teeth can, they prevent me from feeling the food in my mouth, and if I were to just wear them every day I'd have to completely re-learn how to talk. At best, they just look pretty, so all I've ever done with them is take a few selfies with them in. Other than that, they suck and I don't bother with them.

In fact, I have told several people that trying to eat with dentures in is like trying to type with full-finger gloves on. It's both easier and more enjoyable for me to just gum my food. And there are very, very few things I can't eat without teeth, most of which can be mitigated one way or another (and in a couple of cases, "one way" has involved a literal hammer).

What did you use the hammer on?

use a meat tenderizing hammer and make schnitzel like things; crushed nut paste also.

https://en.wikipedia.org/wiki/Schnitzel

https://en.wikipedia.org/wiki/Marzapan

First time was Butterfinger candy. There was a promotion in FF14 where if you bought a certain dollar value of Butterfingers and sent in a picture of the receipt they'd send you a code for a mount.

I bought it expecting to not be able to eat it, just because I wanted the mount. But then I kept seeing the bag on my table and really wanted to eat it anyway. It was full of individually-wrapped pieces, so I took a bunch of still-wrapped candy, a hammer, and a bowl to the landing at the top of my stairs. I laid down on my staircase and went to town on the candy with the hammer. Once it had been thoroughly pulverized, I opened up the wrappers, poured the dust into the bowl, and then just lapped it up out of the bowl.

I specifically did it on the landing and not while sitting at a table or something because I have terrible hand-eye coordination (go go developmental dyspraxia) and the hammer hit the floor more than it hit the candy. If I'd done that at a table, I'd have destroyed the table. And laying on the stairs gave me a better angle to hit it than if I'd just been sitting on the floor.

The next time was cashews. I tried eating them whole but it was too hard, so I got out the hammer and went to my staircase again. Since they weren't individually wrapped I had to get creative. I wrapped them up in a paper towel as best as I could and put it on a paper plate before going to town with the hammer.

With that said, it's been a couple of years since then and it wasn't until much later that I realized my jaw was still healing back then and wasn't at 100% (this was about half a year after my extractions). I could probably eat cashews without the hammer now, though I haven't tried. I still won't touch harder nuts such as almonds, even with a hammer, but it's not a big deal because my teeth were in such terrible shape for years before my extractions that I hadn't been able to eat almonds for a very, very long time.

I lost the distal phalanx of my thumb in my left hand when I was a kid (6 y old). I've lived my whole life without it and have had gone through the full "stages of grief" rainbow and obligatory bullying in school.

Now I am 40 years old and in general my feeling is the following:I would enjoy having a prostetic phalanx which is indistiguishable from the real deal mainly to avoid "distracting" people that I am interacting with. The reaction of most adults is basically to get "distracted" and wondering at some point. I've caught a lot of thease both in public moments (while giving a talk and gesticulating with my hands, you can see into some people's eyes when they "found out", and get distracted). And in private scenarios: I play guitar (more on this later), I've had moments where I am playing with along with somebody else, and you can clearly see when they "realize" about my missing finger. Adults are usually shy/educated and don't ask about it, but it is funny seeing that "moment of silence" when they are pondering whether they should ask and I guess they get "ashamed": "did he realized I stared" ... like, after 30+ years, I don't give a fuck haha.

Now, on the other hand (pun intended), I've researched about prostethics. There are some really good prosthetics which are purely visual. I've never tried those (just haven't pushed myself I guess), but what I would really like is a prosthetic that is more functional. As I mentioned, I play guitar, and one of the things that I am missing is the ability to play some Barre chords as well as I could, or doing shredding (I like to play metal) on some topmost strings, basically because I am missing the "support" that would be provided by the thumb-tip to apply the "force" (don't know if I am explaining myself haha). Also, I've always wanted to play the piano but also ... the remaining part of my thumb won't help with that haha.

So, I guess in summary: for the public side I'd like the "transparent" prostethic, while for me, I'd love to have some prosthetic that would make it easier for me to play guitar haha. Or a laser pointer, or something cool... of course that may be the geek side of me talking.

BTW: I caught your pun

cf. Jason Barnes and his prosthesis designed for playing drums: https://www.youtube.com/watch?v=uyHHxIYOs1g

I can't wait for teledildonic prosthetics. That tentacle in the photo looks like a good start!

Calling u/qdot76367

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