Scientific American: Humans are pretty good at guessing whether a towering stack of dishes in the sink will topple over or where a pool ball will go when a cue hits it. We evolved this kind of physical reasoning to navigate our changing and sometimes dangerous environments. But a new study highlights one area of intuitive physics that’s deceptively difficult: judging how strong a knot is.
7 comments:
This is actually a really interesting study to me. I suppose people don't encounter ropes and knots or interact with them quite as frequently as they do many other objects. They also seem to follow slightly different laws compared to other objects, perhaps due to their materiality. I probably have more experience with ropes than the average Joe, probably due in part to my time with scouts and the joy I always found in untangling knots. I've always like to play with rope. I also was able to look at the knots and just think about how they would interact when I pulled on them. I am not really surprised that most people aren't able to do that, and I'm sure it would be an interesting study to do. I'd like to see more on the way people think about knots and how they try to understand them/why they are unable to. Would mere exposure make people understand them more intuitively?
Human perception is such an interesting thing, especially when it comes to things like this where our snap judgments are wrong most of the time. It's also very interesting that knots which have similar seeming construction such as the four knots seen in the article, can have vastly different strengths just based on which side the ends are on. It makes the lesson Sean West gave in the rigging mini class about how a square knot is not the same thing as a granny knot even though they appear very similar, make much more sense. I am also wondering what the point of the grief knot is if, as the article said, it falls apart when you sneeze on it, that feels like a knot that fails at its one and only job as a knot. Whatever the case, knots are imperative to so many situations it's a little funny that humans are so bad at judging what's going on with them.
I know how to tie a bunch of knots, but guessing the strength of these knots was hard even for me. As far as I know learning what knots are the strongest is a hard challenge that can only be done through memorization of knot types and the ability to understand the simpler knots that go into more complex ones and how they interact with each other. Even with the importance of knowing how strong certain knots for safety reasons, there are few people I know that understand what knots are stronger than others. My favorite knot is the figure eight knot, although I am also partial to any of the knots used in sailing. A fun trick that I like to show my friends is the daisy chain and how quickly it unravels, I will chain a whole length of rope and have them hold one end and I will walk backwards from them with the other letting it unravel between us.
I find it really interesting that people can not intuitively understand what knots are weaker than others. People who have some experience tying knots start to gain an understanding of the basic concepts that make a knot a knot. This then allows them to better understand what can be considered a weak or strong knot. They mention in the article that we run into knots every single day and that should help us determine what knot is stronger but I find that to be untrue. Humans don't spend a lot of time in our everyday lives tying knots making it harder for us to understand the differences between what we are seeing. We also take knots apart by unraveling them rather than breaking. If we went around trying to stress test every knot we came about maybe our intuition would be better but we don't. We mostly just untangle knots by unraveling them leaving us with no information on the actual strength of the spider web in front of us.
Humans not being able to predict what knot is stronger did surprise me a bit, but then I tried the test of ranking the knots and got most of them all in the wrong order. It is really interesting what humans can accurately sense and what they can’t. Humans can go up stairs so efficiently, well only when they are all the same rise lest everyone trips. People can predict where a ball will go after being hit, which is weird to me since I try to kick the ball in the right direction and yet I always kick it in the opposite one, but thats probably just me being bad at sports. Maybe it has something to do with practice, I wonder if people who have enough practice just playing around with rope and knots would be better at guessing knot strength of knots they have not seen before.
Understanding the strengths and weaknesses of the rope and the knots definitely helps to be able to discern which knots are strongest. I guessed that the “reef” knot which I know as the square knot to be the strongest because I am most familiar with it and the thief knot to be the second strongest. The idea behind having the “bitter ends” being opposite each other reducing the load that the knot can handle is interesting and I wonder if it is because the load cannot transfer directly from the rope to the other rope but has to transition across a twist and a bend before it can transfer to the other rope. I wish that this is something they explained more. It is interesting that most people misjudged the strengths of the knots . I wonder what sample of people were studied in this experiment and how often they used or tied knots in their life. Being familiar with knots and knowing what knots are common to tie generally because they are strong definitely helps to generalize which ones are the strongest.
The first time I encountered ropes and knots was when I first started rock climbing when I was around five years old. I think the concept of a rope being something that holds me and will protect me and will be something that will save me with something kind of just something I took for granted or a given because that’s just what I was told and I think this study is an excellent explanation of the human perception is not the best of telling us what is strong and what is not I believe it is essential that this study helps showcase what nuts will be the strongest, most substantial and most useful for different types of activities and things. I also think that it’s vital that the strength of the knots and whatnot will be considered because some knots might not be the most productive in some instances.
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