When sharpening knives, with practice you can tell when you are done by sliding your fingertips along (not across) the sharpened bevel. It’s possible to feel imperfections measured in micrometers this way.
[Thread] Mental Math
Submitted 1 day ago by fossilesque@mander.xyz to science_memes@mander.xyz
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Comments
Geometrinen_Gepardi@sopuli.xyz 1 day ago
pearsaltchocolatebar@discuss.online 1 day ago
If the earth were shrank down to the size of a golf ball, you could feel houses.
SpaceNoodle@lemmy.world 1 day ago
That seems wildly unnecessary. I can already feel houses.
southsamurai@sh.itjust.works 1 day ago
I mean, most people do it across, rather than along the blade, what with the necessity of detecting a burr, which can’t usually be felt length wise. You slide along the blade, and it is sharp, if you screw up you get cut.
That doesn’t take away from what you’re saying, it’s very true, no matter which direction you’re feeling. Just normal, average fingertips can pick up stuff like that, that you’d need a microscope to see. It’s a trip!
Geometrinen_Gepardi@sopuli.xyz 1 day ago
The burr is also detectable lengthwise. When starting with a dull blade it feels smooth while sliding fingers lenghtwise. When the burr is formed, it starts to feel rough. When it feels like it’s digging into skin, it’s sharp. It’s a very subjective thing though, everybody has different fingers.
danekrae@lemmy.world 1 day ago
We have equipment to measure down to microns, and my students often test how fine details they can feel.
DudeDudenson@lemmings.world 22 hours ago
Worked at a machine shop for a while, it’s funny how the easiest way to gauge surface finish is to run your nail trough it
At one of the places we worked at we would know when the rough cut was deep enough just by feel
skittle07crusher@sh.itjust.works 1 day ago
Source??
MeThisGuy@feddit.nl 1 day ago
my half a finger
Geometrinen_Gepardi@sopuli.xyz 1 day ago
milicent_bystandr@lemm.ee 1 day ago
Not advanced maths per se; neural networks are amazing! Fuzzy matching based on experience - taken to an incredible level. And, tuneable by internal simulation (imagination).
HereIAm@lemmy.world 23 hours ago
Don’t be fooled to think computer neural networks is how the brain is structured. Through out history we’ve always compared the brain to the most advanced technology at the time. From clocks, to computers with short and long term memory, and now to neural networks.
milicent_bystandr@lemm.ee 21 hours ago
That is a good point, though the architecture of computer neutral networks is inspired by how we think the brain works, and if I understand correctly there is some definite similarity in the architecture.
Lots of difference though, still!
Zementid@feddit.nl 23 hours ago
I would guess that every statement made is kind of true. It is a clock, a computer and a LLM,…
I would even go as far as LLM is the closest to a functioning brain we can produce. And we don’t understand in detail what it does. Which is ironic.
can@sh.itjust.works 1 day ago
Our bodies n brains are so cool. Think about what goes into locating a sound in space.
bleistift2@sopuli.xyz 1 day ago
That’s boring. Two ears only allow you to put the sound somewhere on a plane (the vertical one that cuts your body in half lengthwise). How do you know the ‘height’ of the sound on that plane? By utilizing the different distortions the sound goes through while being funneled through your auricle.
JackFrostNCola@lemmy.world 20 hours ago
Also that everyones brain has tuned this perception based on their own ear shape, and if you add prosthetic ridges to someones ear they become very bad at determining the noise source direction in blindfold tests.
Dasus@lemmy.world 20 hours ago
Also, moving your ears and your head.
rocketpoweredredneck@sh.itjust.works 1 day ago
My hearing is pretty severely damaged in my left ear, and for several months I thought everything was to my right. but I’ve my ability to locate sounds has come back. My hearings not any better, my brain just figured out that my left ears fucked and compensated.
Zink@programming.dev 1 day ago
I think the “more to it” might be significantly crazier than the timing thing.
Or ears have unique complex shapes that attenuate certain frequencies and bounce sound around in complex ways depending on the direction they ate coming from. And our brains instantly process all that stuff too. It’s why our sense of hearing isn’t just on a flat plane around our head.
Dasus@lemmy.world 20 hours ago
And we can also slightly move our ears a tiny amount, but I’m sure even that does increase accuracy.
GraniteM@lemmy.world 1 day ago
Put on some halfway decent headphones and try out the virtual barbershop.
dukatos@lemm.ee 1 day ago
You can also detect is the source up or down thanks to ear shape which delays sound for couple of ms.
myusernameis@lemmy.ca 20 hours ago
Beyond that there’s been a considerable amount of research about our ability to estimate room size/material/shape while blindfolded just based on the reverberation of sounds in the space.
Oversimplified conclusion, untrained humans are really good at it.
dutchkimble@lemy.lol 1 day ago
In space, no one can hear you scream
Kolanaki@yiffit.net 1 day ago
The second thing about microslippage is why I, even though I would say I’m transhumanist, would only ever go full cyborg if the robot parts had a sense of touch.
I don’t wanna pet my dog and not only not feel their fur, but also end up crushing them with my super strength.
Dasus@lemmy.world 21 hours ago
Also masturbation might be a challenge in that scenario.
KinglyWeevil@lemmy.dbzer0.com 1 day ago
Also the ability of mirror neurons to watch someone do a thing, then conceptualize and execute it with your body is extremely interesting.
Kolanaki@yiffit.net 1 day ago
I’ve seen some pretty awesome prosthetics that are controlled the same way you would use your limbs before they were lost by connecting to nerves; but they still don’t feel anything. At least, not in the sense that the appendage itself is sending signals to your brain for it. There is still phantom sense/pain. You can get a false sense of touch in VR, too.
TopRamenBinLaden@sh.itjust.works 1 day ago
I think with the beginning stages of this kind of technology would work better with a removable option, for this reason. We are already getting able to make better human appendages, with super strength and dexterity, etc., but the touch is something that will probably be hard to implement for awhile.
Schmoo@slrpnk.net 1 day ago
Agreed, until prosthetics can achieve full parity of both function and sensation then they are only good as replacements for parts that are already missing. No sane person is swapping their hand for one that lacks a sense of touch just as good or better than what they have already, even if it’s mechanically superior. In such a scenario that mechanical superiority is desired they would opt for an augmentation over a prosthetic.
Dasus@lemmy.world 21 hours ago
Just earlier today I was googling whether even tooth implants are actually better than the natural alternative.
I didn’t find a definitive answer.
PsychedSy@lemmy.dbzer0.com 1 day ago
I’d take a pettin’ hand and a crushin’ hand.
iAvicenna@lemmy.world 1 day ago
I always imagine it more like neural networks. simply based on a lot of training and experience.
JackbyDev@programming.dev 23 hours ago
My brain is like a brutal network? No way…
iAvicenna@lemmy.world 21 hours ago
more like neural networks are maybe like your brain? dunno not an expert, just a feeling
NikkiDimes@lemmy.world 15 hours ago
Have you ever swiped on your phone, but the screen doesn’t move (due to end of content, or unknowingly being an unswipable screen), and you feel your eyes jerk automatically in reflex, predicting the movement that didn’t happen?
PsychedSy@lemmy.dbzer0.com 1 day ago
Layered as well. Little bits process very specific things and simplify it for the beast.
NikkiDimes@lemmy.world 15 hours ago
Take shrooms and watch as the divisions between the little bits break down into absolute chaos :D
bitwolf@lemmy.one 1 day ago
I was always amazed at how we can catch objects in flight.
Compared to how long it takes me to calculate projectile momentum in Physics 1
buttfarts@lemy.lol 1 day ago
Or tiny birds that can expertly navigate wind currents with an almond sized brain using real-time force feedback. The computational power at their disposal is very well optimized for what they do.
PlantDadManGuy@lemmy.world 1 day ago
Hummingbirds are fucking incredible. They can literally hover, fly backwards, fly inverted, fly silently, or flap their wings loud enough to generate sound waves as a mating ritual. They’re like miniature f-18s dog fighting constantly.
Dasus@lemmy.world 20 hours ago
And they can even do that in sync with thousands (and even millions) of other small birds.
prole@lemmy.blahaj.zone 22 hours ago
Plus they have hollow bones and weigh almost nothing
abbadon420@lemm.ee 1 day ago
If you’re about to walk into a bar with you head, or like the top of a doorpost or smt. You’ll instinctively pull back and avoid the obstacle, inches before it hurts, because your brain notice the hairs on your head moved. That’s why men who have recently gone bald, often have bumps and bruises on their head. My bald colleague told me that for him, that was the hardest thing about going bald.
Anticorp@lemmy.world 1 day ago
So by that logic, a boxer who shaves his head will take harder hits!
Godnroc@lemmy.world 1 day ago
Or does that fractional reaction cause the brain to shift forward more than it would if they had not reacted? Could that reaction lead to worse brain injuries? Makes me wonder.
brbposting@sh.itjust.works 1 day ago
Wow super interesting
Thank you hair! I only cut you out of love!
dovahking@lemmy.world 1 day ago
Maybe I’m understanding wrong but hair don’t have nerves. Is our brain detecting the micro movements of hair follicles inside the skin?
Death_Equity@lemmy.world 1 day ago
Nerves in the scalp.
iAmTheTot@sh.itjust.works 1 day ago
Throwing and catching always amaze me. And it’s not something that everyone is ashtrays great at, for sure, but anyone can try to toss a wad of paper into the waste basket. Whether or not you make it, the calculations under the hood, happening so quickly, always astound me to think about.
merc@sh.itjust.works 1 day ago
What’s amazing is our ability to calculate the path of something in the air.
There’s a test they did with Cristiano Ronaldo where someone kicked a ball to him so he could head it. They shut off the lights before the ball was in the air and somehow from the body shape of the person kicking it, he was able to know how to make contact with it without being able to see it.
prole@lemmy.blahaj.zone 22 hours ago
Pretty impressive, but I can’t help but think that they gave Ronaldo an extra split second than the first dude. Regardless.
Also, I think they’re underestimating/ignoring the input from hearing, especially with the second one where he probably heard the ball bounce hear his foot (subconsciously, of course).
Cool video, thanks.
iAmTheTot@sh.itjust.works 1 day ago
I’m not a fan of Ronaldo but that was very cool to watch, thanks for sharing!
Valmond@lemmy.world 1 day ago
Read somewhere that catching is actually dead simple, just “move towards the image of the incoming target” (I’m not talking about the arm kinematics).
There were a robot paper bin that zoomed under stuff you threw up in the air using no complicated algorithms for example.
Funnily many algos are calked on physical and chemical effects in the real workld, like splines for example were made with a thin metal bar and lead weight bending it to get the lines used in boat hull construction.
prole@lemmy.blahaj.zone 22 hours ago
Read somewhere that catching is actually dead simple, just “move towards the image of the incoming target”
I mean… there is nothing simple about the calculations involved in something like that lol
Emerald@lemmy.world 16 hours ago
I always thought about how interesting it is that handing things to people is so reliable. We just kind’ve know exactly when the other person has grabbed something enough for us to let go.
thedeadwalking4242@lemmy.world 1 day ago
A lot of it is less math and more just approximations using old data, just fitting a complex statistical model neural nets suck ass at math
tigeruppercut@lemmy.zip 1 day ago
Most people who’ve been juggling for awhile don’t need too much additional practice to be able to do at least a few blindfolded catches just because of how consistent your throws get after awhile.
The other thing that’s interesting is how pattern recognition in flying things people aren’t generally used to seeing develops. I used to play ultimate, and when people start learning how a frisbee flies they might be susceptible to chasing it down by following along the path of the disc rather than moving directly to where it’s going to end up. This is sometimes called dogging the disc because (many) dogs do the same thing. But then you learn to “read” the disc and you can tell by the flight path and angle of the disc where it’s going to land.
TheReturnOfPEB@reddthat.com 1 day ago
microslippages: some of us just call it what it is: masturbation
Tarquinn2049@lemmy.world 1 day ago
A lot of it is the difference between learning practically and learning theoretically. You don’t have to understand the underlying mechanics in practice to know how to keep getting the same result. Your brain doesn’t have to be doing any math, it just has to have shaken a bottle enough times to have a good comparative basis formed.
Learning to calculate the current remaining volume in a container when observing someone else shake it… that would use all that theoretical knowledge and math.
It’s like knowing how hard you have to throw an egg at a wall for it to break instead of bounce off. You do it 100 times, you just get a good feel for it. Doing all the math, and then trying to learn it practically is barely gonna affect how quickly you learn it in practice. But if you wanted to make a robot that throws it exactly hard enough without wasting any energy, practical knowledge will have almost no value, and theory and math will be incredibly valuable.
pancake@lemmygrad.ml 1 day ago
The overwhelming majority of all neurons in our body are just for controlling movement. Ironically, things like language or creativity require very little of our computing power and might be replicated by machine learning and a sufficiently beefy computer. But complex motor tasks? We’re way ahead of our current tech on that.
MonkderVierte@lemmy.ml 23 hours ago
The thing about juggling is moot, the point is to throw exactly, so you don’t need to look where to catch. Couldn’t do juggling otherwise.
Hupf@feddit.org 1 day ago
bleistift2@sopuli.xyz 1 day ago
0 3 * * * reboot
Mr_Blott@feddit.uk 1 day ago
Another one is levelling.
A lot of people can see a picture frame is about 0.5° out of level and their fucking eye twitches until the fix it
Me included
That’s nuts when you think about it
ArmoredThirteen@lemmy.ml 1 day ago
I purposefully slightly tilt most my wall hangings. I like watching guests squirm when they mention it and I do nothing
superkret@feddit.org 1 day ago
Sorry cousin, unfortunately I will get the flu this Christmas and won’t be able to come visit.
staticsoar@sh.itjust.works 1 day ago
I respect and hate this. I could never
brbposting@sh.itjust.works 1 day ago
Madlad
Anticorp@lemmy.world 1 day ago
We would probably fist fight then, because I’d level it without saying anything, and if you set it back crooked, I would throw it on the ground.
Senseless@feddit.org 1 day ago
See, I live in an old apartment. The corners aren’t 90°, the wall a picture is hanging on is convex. When I’m lying in bed and look at the picture it looks like it’s crooked but I used a level several times on it and it’s as straight as can be. It’s driving me insane.
Hawke@lemmy.world 1 day ago
But “level isn’t what you need. If the floor and ceiling aren’t level, it’ll look wrong.
Anticorp@lemmy.world 1 day ago
This is when you set it relative to the rest of the unleveled stuff in your view to make it look level.
Eranziel@lemmy.world 1 day ago
I worked on an industrial robot once, and we parked it such that the middle section of the arm was up above the robot and supposed to be level. I could tell from 50 feet away and a glance that it wasn’t, so we checked. It was off by literally 1 degree.
Degrees are bigger than we think, but also our eyes are incredible instruments.
theneverfox@pawb.social 22 hours ago
I remember we once installed something on a beam 40’ feet up. While waking through an inspection of many such things, the engineer stops, cocks his head for a second, and says “that’s not quite straight”
And then it wasn’t. Like a cast of manual breathing, the thing I had been frequently walking past for weeks was suddenly wrong, ever so slightly
prole@lemmy.blahaj.zone 22 hours ago
Leave it up to a civil engineer to ruin your day.
The_Che_Banana@beehaw.org 1 day ago
When my wife was pissed at me she would go to my office before I got to work and tilt every picture/award and move my books about.
She knows what buttons to push and my sous chefs just let her do it… ungrateful pricks
/S
Comment105@lemm.ee 23 hours ago
You have multiple sauce cooks and they’re in charge of office security?