A Magician Explains Why We See What’s Not There | Hacker News Reader

A Magician Explains Why We See What’s Not There

nautil.us

203 pointsdnetesn72 comments

In the field of UX/Psychology there is a term “suffice”. Our brains are constantly sufficing rather that perceiving all data and interpretating it. If we had to do the latter end of the spectrum, our heads would need to be bigger, to the point birth wouldn’t be possible based on current female autonomy. You wouldn’t have survived child birth.

As a result when a person visits a page on a website for the first time people in average scan the page only reading a few words (I’ve hear 7 on average claimed). However, most beginner designers will not realize this and put a couple hundred words on a page with out proper typographic hierarchy. Better designers (same is true for poster designers) use typography and visual hierarchy (Font sizing, spacing/white-space, color, font weight, alignment) to create a design that is easy to scan for a sufficing human brain.

The less scannable the page is the more the brain needs to work to make sense of what is being displayed (higher cognitive load), and the less of a chance the user will read the highest priority data first (the context or hook data).

If the user reads the data in the wrong order, it will likely be confusing noise. The goal of a designer is to present the data in such a way that the signal to nose ratio is high, as they scan and dig deeper into a presented page or poster.

I've always said that the most important job of a UI designer (or graphic designer in the case of posters) is how you communicate with your users.

Unfortunately it's too common that people, specially designers, put aesthetics first.

To put it bluntly, users don't care about the drop shadow of a button if they can't find the damn button or if they don't understand in advance what the button will do.

>the most important job of a UI designer [...] is how you communicate with your users.

>[...] it's too common that people [...] put aesthetics first.

While aesthetics don't need to come first in a design, they do allow a large amount of information -- that you're trying to communicate -- to be encoded in a way that's processed subconsciously and quickly:

A stranger dressed in "war paint" approaches you to sell you a coffee is going to perform worse than a Nanny wearing a warm, fuzzy, cozy, looking sweater.

Dressing in "war paint" vs dressing in a sweater is a form of communication.

For sure, aesthetics are also a form of communication, it's just that it has less impact in the usability of something.

Am I just fortunate that it has been years since these types of complaints have been true with my teams? My recent (last 3-5 years) experience is that modern designers very clearly understand UX vs. UI, and design intuitive experiences to help their audience, not just make a pretty web site. Frankly, that fields has become so mature, with designers having deep understandings of UX to the point where I just sit back, let them soar, and code what they come up with.

The only place I still see poor design work is from coders (myself included), who jump from "I'm good at CSS" to "I'm a great designer"

Perception is actually milliseconds behind reality, due to the nature of the brain processing visual signals. Meditative practice can reduce this delay somewhat.

> birth wouldn’t be possible based on current female autonomy

I'm not sure if that's a typo (anatomy) or an incisive observation regarding women's rights.

Haha, what’s funny is I’m terrible at spelling, so I asked my wife how to spell anatomy she must of miss understood me (she is good at spelling) and she spelled “autonomy”.

The next stage from this is how a spectator remembers a magic trick later on. Good magicians work backwards from this understanding in designing an act or trick. "He put the card in the middle of the deck, and it appeared in his pocket". This is about as granular as the average spectator remembers a magic trick only minutes or even seconds later. It says a lot about how lossy our memory really is even when we are concentrating our hardest. Maybe counter intuitively the harder someone looks the easier it is to direct their attention.

I would recommend anyone learn a simple magic trick or two, if only to help you design your products better. All of the information you learn about how people move through the phases of a trick seem transferable to lots of disciplines.

I remember a magician talking about a particular routine where he did everything, but when the spectators later retold it, they felt like they did it (eg: "I took a card and then..." when in reality the magician gave them the card, something like that anyway). I started reading the book "Sleights of Mind"[1] a while back, I need to go back and finish it. It talks about this subject in depth.

I performed a simple trick for a friend once and then, maybe an hour later, another friend arrived so I performed it for him too. The trick involved swapping something out and doing some very basic sleights to hide the fact that it was swapped. My first friend was watching, knowing the outcome, trying to figure out at what point I swapped, but he didn't spot it. He later asked me "did you swap it before or after X", which I found interesting, because all of the work was done long before X. I love the tricks where the trickery gets done early on and then its just theatrics before the reveal. It really makes it hard for spectators to piece together the events. :)

[1] "Sleights of Mind: What the neuroscience of magic reveals about our brains" -- http://www.sleightsofmind.com/

On this topic, one of my favorite HN comments compares magic tricks to hacking someone's brain:

Magic tricks are hacking! You are hacking someone's mind, particularly their assumptions and attention. The exploits to human psychology and attention are just as sure as the exploits to crack or unlock a smartphone and many other software exploits. The difference is that software can be patched but the evolved behaviors that are the root of the exploits used by magicians are very hard to "patch"...

Full comment: https://news.ycombinator.com/item?id=4992826

Now replace the word 'Magic tricks' with 'Persuasion'

> Maybe counter intuitively the harder someone looks the easier it is to direct their attention.

The Monkey Business Illusion: https://www.youtube.com/watch?v=IGQmdoK_ZfY

That's a very cool illusion, but it's not relying so much on the viewer looking hard, but on training the viewer to explicitly ignore anyone dressed in black. If you asked them "remember everything that happened in the video" you can bet they'd notice the monkey business.

The neuroscience explanation for this is "Predictive coding". These talks are fascinating.

https://www.youtube.com/watch?v=CvAbPtbjxhw&t=1135s

https://www.youtube.com/watch?v=P0yVuoATjzs

Right. So there is a received cognitive operating system which generates an interactive model of 'reality' shaped by historic experience, a facet of this system involves 'hierarchical predictive coding.' When parsing percepts, this subsystem front-loads what aspects of a new experience of interest to accept and what to ignore based on shaping from past experience. A simple example: promise a child a quarter if the correct hand is chosen. Place quarter in right hand then fold fingers up, occluding quarter. Appear to grab coin with left hand, quickly close both hands, and present both fists to child then ask 'which hand holds the quarter?'. Based on past experience it would appear that just a transfer of an object from one hand to another took place so child selects the empty left hand. Then immediately rerun the same test with the new experiential history encoded and find the child (usually with a smirk) chooses the right hand (assuming you didn't pocket the coin to further confuse the child).

Cool videos!

A nice written introduction to the topic of predictive coding is Scott Alexander's book review of "Surfing Uncertainty" by Andy Clark: https://slatestarcodex.com/2017/09/05/book-review-surfing-un...

I have found that book to be an impressive example of poor scientific writing – one long, convoluted, intentionally obtuse sentence after another, as if the author was constantly trying to make the reader feel like an idiot.

I have found some more technical articles (e.g. [0]) very useful, but if anyone knows of a comprehensive introduction that takes more of an experimental psychology angle, similar to Surfing Uncertainty but less frustrating, I definitely want to know about it.

[0] https://www.sciencedirect.com/science/article/pii/S002224961...

"simply looking at the ball. This, however, was not the case: Although they looked at the ball once it had been thrown in the air, they spent a lot of time looking at my face, particularly before the ball reached the top of the screen."

I wonder if self driving car tech thinks about this kind of thing. How often, for example, at intersections, we look at the faces of other drivers and pedestrians for context.

It's interesting to me both as data for the self driving car, and the obvious lack of data for human drivers looking at a self driving car.

It is my experience that I often know what a driver before me is going to do even before they have started to do so. Probably because I pick up very small changes in their behavior, as like reducing their speed a little, even before I have become conscious of them doing so. In theory you could train a neural network to do the same, but it would probably require a neural network much larger than the 'electronic' ones that are being used. I guess our 'biological' neural networks are still much more efficient, energy and size wise, than there 'electronic' versions.

I'm not saying it is, and I'm not saying it isn't, and I definitely have felt the same thing, but it seems to me that the sensation you're calling out is very susceptible to both confirmation bias and post-hoc reasoning. For example, I'm sure your brain fires harder when your "expectation" is met than when it isn't or in all those situations where you just don't make a distinct prediction.

My feeling is that AI would be able to do this much better and more consistently than humans in a relatively short amount of training time.

Provided that for instance all Teslas can learn from all other Teslas' experience.

When teaching my kids to cross the road, I tell them to look for oncoming cars and to make sure the driver can see them (by checking where they're looking) instead of trying to judge if there's sufficient space to cross safely.

What I find interesting is that this varies by country. In some countries, making eye contact with a driver before crossing in front of their car is the right thing to do. In other countries, the best way to cross a road is to pretend that you haven’t seen the on-coming traffic, and to step into traffic without looking at the drivers...

Totally agree. You have to heed your location.

Here in SF, if you look the driver in the eye, you have yielded the right of way to him. Even though state law gives the pedestrian the right of way when they are in a crosswalk.

Speaking as someone who lives in SF, I have never experienced what you describe.

I certainly had plenty of drivers casually and negligently drive through crosswalks occupied by pedestrians (done it myself too when I shouldn’t have)

Or did you mean the “eye contact yields right of way to the vehicle” bit?

I mean the "eye contact yields right of way to the vehicle". In my experience as a pedestrian any time I make eye contact with a vehicle they wave me through, even if my intention was to let them go first.

It is one safety tip you learn when riding motorcycles, however in the realm of self driving cars not only would the face be an interesting item to track but what about hand motions like when people wave you through out of turn?

People who bend the rules like that are a problem to be fixed, not one to be accomodated. I would train the self driving cars to wait until the appropriate conditions are met, and if that means until that person stops waving and continues appropriately, all the better. Road rules are as much about predictability as they are about safety. As long as you can predict another road user will behave a certain way, you can ensure that you can navigate a situation safely without further communication. The moment they start to bend the rules, they introduce uncertainty into the system, which increases the need for communication and the likelihood of mistakes.

This is a fairly fundamental difference between how machines operate and how people operate. People can evaluate and communicate, and it is very inhuman to sit at the intersection with your blinker on while the person who has right of way is frantically waving you on because of some reason. And while you would fail your driving test if you did accept permission to proceed, the reality is it is known and accepted and expected that people will adjust in more normal situations. To the point I recall being explicitly warned of this exact situation before taking my test. And I recall that because it actually happened during my exam, and I was amused at the uncomfortable feelings as I kept my hands on the wheel and ignored the adult giving the young novice permission to go while they rummaged in their glove compartment.

I do agree that self driving cars should wait until appropriate conditions are met, because they can't make rational decisions. I think while there are mixed self-driving and human driven cars on the road, there will need to be some sort of visible differentiation for cars running in autonomous mode, because they are never going to react the same as humans unless we teach them to react as badly as humans ;)

I got bored a couple of years ago and decided to start learning some magic.

If anyone wants to learn card magic, there are an unbelievable amount of tutorials on YouTube.

All you need to do some very impressive tricks is a single move — the double lift.

Can you link to some of your favorites?

I started learning myself in late November 2017. You can get a LOT of mileage off a $10ish book too (eg “expert card technique” or “royal road to card magic”[1])

But yes, I follow a few YouTube channels that have taught me a lot: Xavier Spade, Alex Pandrea, PigCake and a few others. There are some excellent ones, but I noticed that you do have to be careful, there's a lot of "reveals" or "tutorials" that are done by hobbyists and their quality is varied, some would teach bad handling or bad habits. They can be fine to get the concept, but maybe not as an absolute beginner. The ones done by magicians who perform professionally tend to be great quality though. But you probably know this better than I, since it sounds like you've been doing it longer :)

Its really easy to find tutorials and guides nowadays, you just gotta put the time in!

I personally don’t actually like the double lift because I find that 90% of them, even though they are perfectly executed, just don’t look natural — most laypeople simply would never turn cards over in the way most magicians do and it just looks fishy. Having said that, most laypeople don’t actually notice (it’s ibcredible what you can get away with sometimes!) but I notice it and it puts me off :)

[1] A side story on this book... I may have cost the publisher a bit of money... They have a "video edition" of the book, where many of the techniques and routines have a QR code linking to a video, but when I got it, all of the links were broken. So I complained to the Advertising Standards Authority (UK) and about two months later, all of the QR codes started working. I noticed that they all directly linked to Rackspace CDN URLs (ie not to their own domain). I can't imagine it was fun or cheap to get the exact same identical URLs working again...

I’ve been doing magic half professionally on and off for almost a decade now. Basically, I don’t do card tricks anymore and the reason is simple - if you were to do real magic, would you do it with playing cards?

On a side note, revealed card tricks on YouTube were my pain in the butt for a long time, but I don’t care anymore.

Playing cards can be a nexus of strong emotions and violence, and they exemplify the uncertainty of life and the greed/addictive tendencies of living things. From that perspective then seem as much a magical talisman as chicken guts and such.

From the other direction, a card shark might say that doing magic with cards makes it a practical skill and takes away the magic :)

I believe tarot cards started out as simple playing cards. I suppose if one could do "real magic" with cards, divination would probably make more sense then sleight of hand.

If you could actually control probability and make small objects appear and disappear through physical manipulation then there would be much better uses for that then street magic.

I agree that cards are somewhat unnatural for the average random person and I remember seeing a youtube video where a magician did a (not so scientific) test so see what people preferred and I believe he tested cards, sponge balls and elastic bands and most people preferred the sponge balls. I do think that the "tricks with everyday objects", especially if spontaneously obtained (from the spectator if possible!), are the most memorable, but at least pretty much everyone knows what cards are. I've got some pretty great reactions with cards.

There's also the school of thought that its dishonest to pretend you have real magical abilities and therefore you don't have to simulate real magic, instead treating it as the performance art that it is. Most people know its a trick and don't mind that its not totally believable. That said, you're probably right in that your way leaves a more lasting impression.

Re: youtube, magic is a really bad art for video, IF you're the kind of person who only enjoys magic if it baffles you and once you see how its done (even just partially) then it gets boring and with a video, where you can watch it 100 times, in slow motion, of course people will always see something they shouldn't. Sadly these people often see it as a challenge (I find the "pretend to have powers" magicians are largely at fault for this, IMHO) rather than as a performance art. Oh well.

But those are just my thoughts, I'm not a professional and have never performed for money or in front of more than a handful of people, so you know a lot more about it than I do!

I see some interesting thoughts here. I agree that pretending to have magic powers is not a good way to perform. That being said, I think the concept of doing tricks so powerful that audience has no explanation other than believing in magic is completely orthogonal to an idea that you are supposed to brag about having paranormal abilities.

I think the art of magic is ought to be performed live. There some guys who got it right on the TV, for instance Copperfield. The problem with YouTube on the other hand, is that you can replay the video anytime, so this kills misdirection entirely.

The way I get around this issue in my promotional materials is that I basically only show people’s reactions to my effects, so that people see what they buy. Entertainment, not tricks to figure out.

On a side note, I love how Derren Brown performs. He says up front, he has no psychic powers but provides some basic pseudoscience explanation to his audience which is a trick on its own!

Yes! I completely agree.

> Entertainment, not tricks to figure out.

Exactly. I personally really enjoy figuring out how they work and, for example, I’ve learned how Shin Lim does (parts of) most of his routines (partly through watching them over and over and partly by buying his “52 shades of red” routine instructional — I learned so much from it, even if I’ll never perform his routine!), but it doesn’t detract from my enjoyment of watching him perform, because he is a great showman and has incredible skill. I still enjoy watching him perform 52 shades and in some way even enjoy it more knowing how it’s done. Having said that, I do also enjoy the mystery too, so I don’t try to learn everything either.

Probably my favorite trick, in terms of not lying to the audience, is a trick Teller does (The Red Ball) which Penn introduces simply as "Now, here's a trick that's done with a piece of thread". And AFAIK that's the truth, and the trick is spectacular because of the things Teller is able to do with just an invisible piece of thread. I only skimmed this article about it but it matches up with what I recall reading before: https://lasvegasweekly.com/news/2008/nov/20/man-ball-hoop-be...

There may be a different video but [1] by Steven Bridges is similar to what you describe. It's not very scientific but he interviews several groups about their preferences between a very similar trick being perform with sponge balls vs with casino chips.

[1] https://www.youtube.com/watch?v=puEcPpRqdx8

Ah, maybe this is the one I was thinking of and I misremembered it a little. It certainly looks familiar.

> All you need to do some very impressive tricks is a single move — the double lift.

As someone who has had a casual interest in card magic and sleight of hand, here’s an observation about how so many different tricks can come out of such a seemingly simple sleight.

There’s a fairly simple formula that makes it possible to be very creative and come up with endless new tricks and variations.

At the heart of any trick is some sleight, such as the double lift, where the illusionist creates a seemingly trivial rift between reality as the audience perceives it, and reality as it actually is.

The illusionist can then get creative with what to do with this difference.

Usually you maintain the facade and do things that would be possible in both realities. From the audience’s point of view, it’s like the trick hasn’t started, when in a sense it is already over. Then, at a safe distance from the original sleight of hand, in terms of time and attention, the illusionist can now seem to break the rules of the reality the audience believes in, simply by revealing the difference between the two realities.

This allows you to amplify an underwhelming “Ok, so I couldn’t see that you picked up two cards” to a very impressive “Wow, my card magically reappeared at the top of the deck after you put it into the middle of the deck and let me shuffle it”.

Ah, good old time-misdirection! I love it. You explained it very well and gave me something to think about for my own routines.

Really nice explanation, I kind of knew the idea in practice, but can't remember having seen it so well explained before!

Here's a thing I still wonder about:

I used to practice forcing, so I get the general idea. What I used to do was mind-reading etc, but there's one particular event that stands out for me, here is what I think I saw:

A pro magician shows up in a birthday party showing a deck of cards, asks the host to think of a card, shuffles the deck and shows the card, confirming with the host that it is correct, then goes on to do all kinds of amazing tricks where this card shows up again and again.

In my mind, there are only a few options here:

- they agreed on it (too risky. This bloke does big jobs, won't do that in an ordinary birthday.)

- somehow influenced the host ahead of the selection process (how? when? Is this actually possible with NLP or something? Something about the setup of the deck?)

- maybe he tricked us into thinking he had a full deck and all there ever was was 4 of clubs? (Sounds crazy, bit not impossible for a guy who'll pickpocket the craziest things, walk around with a flying piece of furniture while exposed to 180 degrees of audience, non staff on the stage and a TV crew filming.)

- somehow guessed it based on eye movements (what I used to tell when I did stupid "mind reading" tricks that was only stupid forces)

- somehow tricked the host into thinking this was the chosen card even if it was another (again how?)

Anyone wants to share pointers? A few words, links to books, web sites, anything?

How many times did you see this magician perform? If just the once, then it’s also possible that the magician just lucked out. I know of magicians who will always ask an audience member to think of a card as the first thing, just in case they happen to pick the card that the magician knows is the top card (by briefly peeking or by having it set up). If it is, then the magician looks amazing. If not, then the magician performs another trick instead and the audience is non the wiser.

I don’t know how what you described was performed, but I know that magicians often leave themselves multiple outs in case the audience doesn’t do what they want them to.

https://www.youtube.com/watch?v=6YIPtJlCbIA

Here's the hollow mask illusion, one of the most fascinating parts of the article for me.

My favorite part of that is the fact that the perception of the hollow mask rotates in the opposite direction as the actual hollow mask does.

> What this shows is that participants used my face to predict where I would throw the ball

Being someone who likes to avoid eye contact, this explains why when I'm walking I always end up doing the get-past-you shuffle.

I had; and to a certain degree, still have this issue.

But I got my rate of doing the "get-past-you shuffle" down quite a bit after learning a simple trick.

While I avoid eye contact, most people do not. Most people, when they see an on-coming person, judge which side (left/right) to pass them by looking at their gaze.

The trick is to look in the direction you want to pass the other person in. So if you're going to take the left side, look to your left.

Most people will then pass you on your right side.

Yep, head facing is maybe even better than eye contact. In addition, local road rules even out the rest (e.g. which side of the road do people drive on in the country where you are currently walking).

Definitely head facing. If I'm anticipating a collision, I generally turn my head slightly in the direction I'm going even if I don't move my eyes. I think of it like my nose is pointing to the side I'm going.

Another good technique is to commit to avoidance early, and stick to it. For example, when you notice the collision course, start bearing left immediately - the other person may have started to move in that direction, which would normally start the 'shuffle' as you both shift to your right, but you short-circuit that by not reciprocating - keep left. Seems like it might be rude, but in practice it doesn't seem so, the relief outweighs any ill feeling (or so I imagine!)

A quick hand wave in the direction you're going works even better

Another is to just stop, stand still, and wait for the other person to solve the situation. I've realized how terrible I am at dealing with those situations so that's what I've started to do.

Great advice! I'm definitely going to put this into practice.

> One of my other truly astonishing skills involves throwing a ball one meter into the air and catching it.

A true miracle of coordinated tracking, movement, and prediction. I'm delighted to see such a seemingly-trivial thing called out as the remarkable feat it is.

If you feel it is quite mundane, consider how much work it would be to automate.

He mentions people looking at his face to aid in predicting what the ball's trajectory will be.

I wonder what eye tracking data from those with high-functioning autism (or whatever they call what we used to call Aspergers) would reveal, since "face blindness" and the inability to interpret facial expressions are typical hallmarks in those individuals?

That is, do such individuals experience a degradation in coordination in such tasks, and/or related tasks, due to such inabilities?

Or do they make up for it in other ways?

The example of Agnosia cited in the article indicates that there wouldn't be any degradation. Proprioception and physical interaction seem to have their own dedicated pathway.

If not being able to tell vertical from horizontal didn't affect the patient's ability to interact with the world, why would not being able to tell if a face is "happy" or "sad" have an impact?

This reminds me of an old legend (probably made up but what do I know) that when early European explorers first reached North America, some native American tribes, then settled on the shore, were unable to see the ships coming on the horizon, until one of their shamans pointed at them, because only they had the necessary conditioning and open mindedness to perceive and anticipate things that were unfathomable to others.

I'm 100% certain that didn't happen, and /r/askhistorians seems to agree[0]. Humans just don't work that way.

[0]https://old.reddit.com/r/AskHistorians/comments/3lh0kz/is_it...

Thanks for the link. Sounded a bit hard to believe indeed (although if it were true it would more likely come from Native American folklore rather than the other side, for I can hardly imagine how they'd be able to recollect that story from their viewpoint).

I remember seeing that in a documentary about perception "WHat the bleep do we know?". I might have found some original reference at some point in a book about Magellan arriving for the first time at Tierra del Fuego. I don't remember the details.

I see what I know I see what I know I can see

We don't really 'see' things. Rather our eyes are just one of the means by which we correct our guesses about what's out there.

One must always marvel at the mental gymnastics neurotypical people go to to explain why their hallucinations are actually a good thing.

Implying that said hallucinations, tailored by evolution, are actually a bad thing.

People outside the WEIRD (Western, Educated, Industrialized, Rich, Democratic) populations don't experience them. They are not shaped by evolution, but likely by the excess iron in western food that gets into the brain and shifts the brain chemistry towards a psychosis like state. (you can look up studies on rats, or I can look up some if you want)

People who are immune to it have Asperger's or something similar "on the spectrum".

Anyway, here is one: https://www.ncbi.nlm.nih.gov/pubmed/6138953

I'm totally shocked that a wacky theory proponent (complete with zany acronym!) would link an article talking about iron deficiency to promote their wacky theory that excess iron causes a psychosis like state.

That acronym is well established in psychology.

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