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It's Surprisingly Hard To Notice When Moving Objects Change

Soulskill posted more than 3 years ago | from the sorry-officer-the-traffic-light-was-swinging-in-the-wind dept.

Science 140

An anonymous reader writes "Scientists at Harvard have found that people are remarkably bad at noticing when moving objects change in brightness, color, size, or shape. In a paper published yesterday (PDF) in Current Biology, the researchers present a new visual illusion that 'causes objects that had once been obviously dynamic to suddenly appear static.' The finding has implications for everything from video game design to the training of pilots."

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Is that why ? (2, Funny)

ls671 (1122017) | more than 3 years ago | (#34798998)

Is that why my wife is always running around ?

Re:Is that why ? (0, Flamebait)

Anonymous Coward | more than 3 years ago | (#34799072)

Re:Is that why ? (1)

no1nose (993082) | more than 3 years ago | (#34800910)

+1 - Keep your vasectomy secret...and always use a condom!

Re:Is that why ? (1)

Beardo the Bearded (321478) | more than 3 years ago | (#34799422)

No, there's an even faster naked man behind her.

Re:Is that why ? (1)

Anonymous Coward | more than 3 years ago | (#34800062)

It's an extension of Heisenberg's principle: It is possible to know how much weight a person is gaining, or how fast they are walking, but not both at once.

Re:Is that why ? (0)

Anonymous Coward | more than 3 years ago | (#34802442)

Is that why my wife is always running around ?

so that nobody notices she is getting fatter

I don't see it. (1)

dnormant (806535) | more than 3 years ago | (#34799016)

It's Surprisingly Hard To Notice That It's Moving!

Re:I don't see it. (1)

SomeJoel (1061138) | more than 3 years ago | (#34799242)

I don't see it either. It's either slashdotted or just a really crappy site. There's no motion at all.

Re:I don't see it. (2, Informative)

Anonymous Coward | more than 3 years ago | (#34799328)

Follow the link to the youtube video - they have the bandwidth!

News Flash (1)

freeze128 (544774) | more than 3 years ago | (#34799714)

News Flash:

Humans find it difficult to notice things they are not looking at! Film at 11.

Re:News Flash (1)

ehrichweiss (706417) | more than 3 years ago | (#34800174)

I was thinking the same thing. For one, I COULD see the colors change but my peripheral vision is more developed than most(I can even see color with it).

Re:News Flash (1)

nomel (244635) | more than 3 years ago | (#34800406)

"I can even see color with it" ...is this supposed to be odd or something?

Re:News Flash (3, Informative)

Z34107 (925136) | more than 3 years ago | (#34800680)

"I can even see color with it" ...is this supposed to be odd or something?

Yes, because only the cones [wikipedia.org] in the center of your eye are capable of perceiving color (the rods on the outside perceive only black and white.) Your brain senses everything in the periphery of your vision in black and white, but "fills in" best-guess colors from what your cones perceive directly in front of you.

I remember that from a psychology lecture only because a fellow classmate, like the parent poster, couldn't believe the color in his peripheral vision was an illusion. So, the professor drew an "X" in the middle of the chalkboard and asked him to stare at it without looking away. He then held up a colored note card directly in front of the "X" and asked him to name the color. (Of course, he named it correctly.)

The professor held up another note card, a bit further away from the X, and asked him to say what color that card was. And then he held up the next card, a bit further away from the X than the last one. And he kept holding the cards further and further towards the edge of his field of vision.

After about the fifth card, the kid was convinced that any card the professor held up was either a shade of gray, or the same color as the chalkboard. Once the note cards were in his peripheral vision, he couldn't tell what color they were, and couldn't tell that he couldn't tell what color they were. Great professor.

Re:News Flash (4, Informative)

NeutronCowboy (896098) | more than 3 years ago | (#34802692)

Uh, did you read the Wikipedia link you posted? "Cone cells are densely packed in the fovea, but gradually become sparser towards the periphery of the retina." They aren't located only in the fovea, but all across the retina. They're merely more densely packed in the fovea than towards the edge. What most likely happened to your classmate is cone bleaching [ucsd.edu] : the longer you stare at a particular image, the more the particular cones bleach their photoreceptors, and the harder it is to figure out the correct color. Depending on what color the chalkboard was, it's quite possible he simply had stared at it for too long.

The retina still perceives color at the edges, it just does so less effectively than if you focus on the center.

Re:News Flash (1)

Vegeta99 (219501) | more than 3 years ago | (#34801116)

wait, is this really all they're tryin to prove? I'll admit, I pulled a non-RTFA, but shit, I've known for years that peripheral vision was not great at discerning detail. I've done degree tests, and while I can detect items slightly beyond the 180 degree plane, I have no clue what they are. If that's their point, this is first-year psychology shit. The center of human vision is accurate yet less sensitive to movement, and the peripherals are vice versa. That appears to be the way things should be, an object coming up out of direct view SHOULD be easily detected as movement, detail is not necessary. Conversely, in the center of vision, detail is more important that sensation of movement, which can be easily extrapolated.

Re:News Flash (4, Insightful)

Jesus_666 (702802) | more than 3 years ago | (#34801642)

Except that's not what they tried to show. The site demonstrates that when objects are moving relative to your field of view you become less able to discern changes to the objects themselves, whether it's a change in coloration, size or shape. This is not interesting because your peripheral vision is bad - when the objects are stationary it's easy to tell that they are changing - it's interesting because it's a property of human vision that apparently wasn't known yet.

In fact, just try to focus on one of the dots in the videos. Even if you know it's going to move, you know it's going to keep changing color and the dot is in your center of view you still might fall to the illusion (not to mention that other dots nearby also seem to be unchanging even though they're right next to the one you're trying to follow).


It's not about central vs. peripheral sight, it's about how motion and the perception of change interact.

Re:News Flash (1)

AK Marc (707885) | more than 3 years ago | (#34802550)

When I debated getting an advanced degree in psychology, this is what I would have done my thesis on. 20 years ago. Though I was going to work it as predisposing a person to declare an unclear object as something, then when the image becomes more clear, how long after it's clear from a still image until they can identify it's not what they thought it was. The point being that if you are driving along and see a bag blowing and mistakenly identify it as a squirrel, it will take longer to identify it as a bag than if your brain hadn't already decided. As long as the image is changing and moving, the brain will hold the last "belief" until long after it should have changed the initial guess.

But then, that's something I noticed when learning to drive and trash and animals are common and I noticed my errors and I couldn't explain why the errors were happening even when I knew the problem and expected them to be coming. When I was considering the advanced degree, it made sense to examine something I fully expected to "prove" that the brain refuses to accept new info unless some currently unknown threshold is passed proving the previous information false. Even then, there are studies that show that when you prove someone's beliefs false, they believe the false beliefs even more strongly. The brain is broken in many ways.

Slight of hand (4, Interesting)

Anonymous Coward | more than 3 years ago | (#34799054)

I think this was fairly well known (at least intuitively) by magicians. As long as you keep your hands moving, people can't tell what you are doing with them.

Re:Slight of hand (4, Interesting)

PopeRatzo (965947) | more than 3 years ago | (#34799192)

I think this was fairly well known (at least intuitively) by magicians. As long as you keep your hands moving, people can't tell what you are doing with them.

Sleights of Mind: What the Neuroscience of Magic Reveals about Our Everyday Deceptions by Stephen L. Macknick and Susana Martinez-Conde.

I saw this book at the Bucktown branch of the Chicago Public Library earlier today in the "New Non-fiction" section. I took it out but haven't had the chance to crack it yet. It looks like it speaks directly to your point.

This is from the blurb:

Stephen Macknik and Susana Martinez-Conde, the founders of the exciting new discipline of neuromagic, have convinced some of the world's greatest magicians to allow scientists to study their techniques for tricking the brain. This book is the result of the authors' yearlong, world-wide exploration of magic and how its principles apply to our behavior. Magic tricks fool us because humans have hardwired processes of attention and awareness that are hackable—a good magician uses your mind's own intrinsic properties against you in a form of mental jujitsu.

Now magic can reveal how our brains work in everyday situations. For instance, if you've ever bought an expensive item you'd sworn you'd never buy, the salesperson was probably a master at creating the "illusion of choice," a core technique of magic. The implications of neuromagic go beyond illuminating our behavior; early research points to new approaches for everything from the diagnosis of autism to marketing techniques and education. Sleights of Mind makes neuroscience fun and accessible by unveiling the key connections between magic and the mind.

Re:Slight of hand (2)

Em Adespoton (792954) | more than 3 years ago | (#34799822)

It's actually slightly more complex than that; a Magician's task is to use body language, banter, props, etc to make people see one part of the picture while ignoring another part... and using humans' built in narrative creativity to fill in the hole (which is where you do the tricky stuff) with something from their own mind. Of course, moving your hands in *almost* predictable, common ways tends to fool most people into thinking that's exactly what you're doing.

The techniques used in parlour magic and stage magic are, obviously, slightly different. This trick of "motion masking" is used in both venues however, although for slightly different effect in each.

This isn't all that new (3, Interesting)

Monkeedude1212 (1560403) | more than 3 years ago | (#34799064)

Our eyes are trained to do a whole lot of quick thinking and estimates before sending the raw data to our brain. This is one of the many reasons why simply hooking a camera up to the optic nerve doesn't quite produce the desired results - though our brains seem to be super-learning computers able to interact with almost any other kind of Input - Output, given enough time for trial and error.

I imagine our Eyes are trained to generalize the colour it sees and focus on the appearance of motion, because thats usually more important and relevant to survival, and our eyes are just like technology: Limited bandwidth.

You might call it a defect, I might think of it as evolutionary design.

Re:This isn't all that new (3, Informative)

JordanL (886154) | more than 3 years ago | (#34799908)

You might call it a defect, I might think of it as evolutionary design.

I call it evolutionary accident through a process of natural selection propagated by random mutations and favorable environmental factors to suppress competing alleles.

Re:This isn't all that new (-1)

Anonymous Coward | more than 3 years ago | (#34800478)

Hey Jordan, you might want to have a look at your MySQL server. ;)

Re:This isn't all that new (0)

Anonymous Coward | more than 3 years ago | (#34800722)

Looking at the link in your signature:

Warning: mysql_connect() [function.mysql-connect]: Unknown MySQL server host 'mysql50-04.wc2.dfw1.stabletransit.com' (1) in /home/jordanl/public_html/header.php on line 35

Warning: mysql_select_db(): supplied argument is not a valid MySQL-Link resource in /home/jordanl/public_html/header.php on line 36

Re:This isn't all that new (0)

Anonymous Coward | more than 3 years ago | (#34801288)

Monkeedude says some pretty funny things, the funnies of which is:

"Our eyes are trained to do a whole lot of quick thinking and estimates before sending the raw data to our brain."

I feel a bit pedantic, but our eyes send raw data to our brain which has trained itself to make reasonable assumptions about what is being passed into it. Your eyes don't have their own processors.

Re:This isn't all that new (4, Informative)

Jesus_666 (702802) | more than 3 years ago | (#34801732)

That depends on what you call a processor. The eyes do a bit of preprocessing - the raw output of the rods and cones isn't fed directly into the optic nerve; intermediate cells inhibit and excite each other, altering the image in-eye. One example of retinal filtering is how Mach bands [wikipedia.org] are created: Lateral inhibition between the cells causes edges to appear more pronounced than they actually are. The brain is not involved.

(Essentially, the more light one cell receives, the more its neighboring cells are inhibited. At an edge between a light and a dark area, a "light" cell close to the edge will receive less inhibition than entirely bright-surrounded cells due to its "dark" neighbors and thus the light side of the edge will be perceived as brighter. Conversely, the "dark" cells closest to the edge will receive stronger inhibition than other "dark" cells due to their "bright" neighbors, causing that side of the edge to appear darker.)

Re:This isn't all that new (1)

Hognoxious (631665) | more than 3 years ago | (#34802802)

I imagine our Eyes are trained to generalize the colour it sees and focus on the appearance of motion, because thats usually more important and relevant to survival

If our ancestors had gone through millions of years avoiding ambushes by flying man-eating chameleons it might be different.

Different kind of change (4, Informative)

pz (113803) | more than 3 years ago | (#34799082)

IAAVN (I am a Visual Neuroscientist). It's a compelling illusion. I have not read the original paper, but will speculate nevertheless in true Slashdot fashion. The change that's perceived before the ring rotates is not so much due to the colors changing -- if you pay close attention -- but something that's called apparent motion. The classic example of apparent motion is the sequencing of lights around a movie marquis -- they appear to move, although the lights themselves are not actually moving. In the same way, the static ring has internal apparent motion as the colors change, because your brain is interpreting, for example, one dot turning yellow next to a dot that was previously yellow, as motion of a yellow dot, even though the underlying dots do not move. While apparent motion can be very strong, it is not the same as true motion.

Then, when the ring starts to rock back and forth, there is a true motion signal that swamps the apparent motion. If you pay attention to a given dot while holding your gaze still fixed at the central white point (not as hard as it sounds), you can clearly still see the colors changing.

So without having read the paper, I reserve some skepticism that they have not actually measured what they think they have. Change is still perceptible, but it would seem that real motion interferes with apparent motion.

Re:Different kind of change (1)

DCFusor (1763438) | more than 3 years ago | (#34799292)

I won't disagree with a pro on this, you're probably right that they didn't measure what they thought -- as Feynman pointed out, even with rats, a good experiment is truly difficult to design.

On the other hand, the premise might be believable even if the experiment is flawed. Humans needed to detect motion above all else to survive earlier on in evolution, as something moving might have plans to eat one of us. We can see tiny movements where we can't see diddly staring right at the same thing motionless -- read any sniper training manual for more on that one. So the super sensitivity to motion is a well known thing, and I would suppose that would make it easy to distract one from changes in the thing moving, because for one thing, that doesn't usually happen and when something is moving, it's mostly the ac coupled edge detectors in your neural nets firing, which isn't the same stuff as what you use to see a shape so much. Probably just drowns that out a little for most observers who haven't specially trained to notice things like that -- evolution wouldn't seem to require telling if a tiger changes into a panther during a leap at your throat.

Re:Different kind of change (4, Insightful)

calzones (890942) | more than 3 years ago | (#34800216)

I think in this case, when the ring is static, each individual object is a unique entity. Changes matter.

When the ring is in motion, each individual object becomes part of the whole. It is now one ring and we ignore changes occuring to the ring.

This is entirely sensible because when an animal is in motion, we don't care about the muscles rippling, or the feathers ruffling, or the fur shimmering, or the shadows from trees dancing on it. Our survival depends on being able to watch the animal itself as a single unit. So we are hard wired to ignore the micro changes to a single object.

When the ring moves, all the tiny objects join to become a single ring we must track. When it's not moving, we see they are separate objects.

Re:Different kind of change (0)

Anonymous Coward | more than 3 years ago | (#34802000)

That suggests an experiment to carry out: have the objects in the ring move, but have them follow differing trajectories (so they move relative to their neighbours). Would the tendency to see the ring as a single item be reduced to the point where each separate object becomes 'unique', and would the ability to detect changes in colour/shape/size increase accordingly?

Re:Different kind of change (1)

aXis100 (690904) | more than 3 years ago | (#34802446)

I think the illusion in this is because it's a group of shapes, plus persistence of vision - just like any other animation. My brain tracks the common sizes/colours spinning aroubnd, not original entities.

If it was a single shape moving I could see the changes.

May I introduce the 'blue collar' POV?.... (0)

Anonymous Coward | more than 3 years ago | (#34802638)

We can see tiny movements where we can't see diddly staring right at the same thing motionless -- read any sniper training manual for more on that one.[...]Probably just drowns that out a little for most observers who haven't specially trained to notice things like that -- evolution wouldn't seem to require telling if a tiger changes into a panther during a leap at your throat.

I think I can address this with confidence as a trained and experienced ex-US Army sniper with the ranking in the top ten US military snipers[1] until the Iraq war...

Two things can foil a good sniper consistently...an alert individual that pays attention to detail(a surprisingly small subset of humans!), and an individual who is good at pattern recognition(another extremely small subset of humans. Fortunately, there is only a small overlap with these two subsets!(from a sniper POV)).

For example:
Few people will catch me stalking them until i make the shot. This includes trained observers on a staged training/qualification exercise. I could stalk my target to a surprising distance and take my shot...even when the target had a time frame and specific area I would be operating in. I could usually get within 30(thirty) meters of my target to take my shot.
In the 'real world' (for me, that was Berlin, and my targets were the STASI and their Soviet advisors/watchdogs), the odds were much better in my favor...I never got caught as a sniper! 67 confirmed, 183 probable FTW! No Regrets.

Where I got 'busted' on training/qualification courses was when the observer was alert and paying attention to detail. 'Hey, that clump of grass wasn't there fifteen minutes ago?!? Maybe i need to keep an eye on that?'

Or the 'pattern recognition' type: 'What doesn't belong in this picture?...Hmmm...when this started, that clump wasn't there...it was over there...Hmmm'

End result....busted!

However, most people just don't pay attention, and are super-easy targets. It's just a small subset of panicky, paranoid individuals that make work hard for snipers. I would postulate that 99.8% of humans are easy targets, in my experience.

Snipers and stage magicians both take advantage of human psychology and visual misdirection. It just plain Works.

You are correct IMHO about the evolutionary need for detecting movement as a visual priority over detail

[1] 67 confirmed kills, with 183 'probable kills', I was #6 or #7 until the Iraq war. I haven't felt the need to check on my 'current status', as that is a past I still have mixed feelings about, but colleagues and peers inform me that I am now #13. For reference, I served 1977-1980 In the US Army- before the Berlin Wall came down.

Re:Different kind of change (1)

JSG (82708) | more than 3 years ago | (#34799330)

IANAAVN and I too can't be arsed to read the paper either and of course I've only skimmed your response. Now for my speculation:

The classic gorilla in the room http://viscog.beckman.illinois.edu/grafs/demos/15.html [illinois.edu] experiment is a far better demonstration of how our perception is rubbish.

Farting around with dots and rings just isn't going to get you on the news.

There are tons of static optical illusions which even when you know how they work, still work. This is probably a dynamic optical illusion.

Perhaps we both ought to do some reading so we can say something usefull. At least, you ought to read up on it seeing as its in your field!

Cheers
Jon

Re:Different kind of change (1)

pz (113803) | more than 3 years ago | (#34799524)

The gorilla illusion is not the same. That's an illusion based on the limitations of our attention; it is not a change illusion.

Fair point about reading the paper. I've downloaded and done a quick first read-through. If you look at Figure 1, they show the results for the four different kinds of change they tested, hue, luminance, size, and shape. The first two are more readily interpreted as apparent motion when the changes are slow. Their results show that the first two illusions are more susceptible to interference from the rocking motion. Watching all four movies shows that the first two (hue and luminance) have a definite apparent motion component with clockwise rotation, that the other two illusions lack. At least to my viewing.

They've done a very good job, and I would have believed the paper more if I hadn't seen the illusion. They've measured a definite interference between real motion and something, but the something has been confounded by apparent motion.

Re:Different kind of change (1)

JSG (82708) | more than 3 years ago | (#34799890)

Bugger - I'm going to have to do some research! Time for some reading, its almost as though a /. story might become interesting.

Right - I cry foul almost immediatly (I've only watch the first vid):

Its common(ish) knowledge that the visual field is very narrow. The fovea centralis http://en.wikipedia.org/wiki/Fovea_centralis [wikipedia.org] only covers a very small area, and I'd be willing to bet (only a small amount) that causes the apparent lack of movement.

You are instructed to concentrate on the central dot and the gap to the ring seems to be big enough to put the dots outside of the fovea's view. However run it again and concentrate on the ring and yes, the dots still mostly seem to stop blinking, however you can still perceive blinking.

The rate of rotation is quite quick and there is a 60Hz refresh on my laptop screen - was that controlled for or even considered? What sort of screen was the real experiment carried out on?

I still say this is an optical illusion of some sort unless someone who knows what they are on about can convince me otherwise.

Cheers
Jon

Re:Different kind of change (5, Informative)

suchow (1972574) | more than 3 years ago | (#34800554)

hi jon, i'm one of the authors of the paper. just thought i'd answer your question about the refresh rate. we used laptop screens that ran at 60 Hz, but the demo works even if you keep the dots motionless and lift up the screen and rock it back and forth. (you can try this yourself if you download the video.) the demo also works on a CRT at 120 Hz. so yes, it the refresh rate was considered and controlled for, and it doesn't seem to matter much. the motion in the youtube and vimeo videos are a bit jerky because they were converted to 30 fps.

Re:Different kind of change (1)

JSG (82708) | more than 3 years ago | (#34800798)

Blimey - that's an answer from above!

Thanks for your response. Its rather more than you get on /. normally

Cheers
Jon

Re:Different kind of change (1)

JSG (82708) | more than 3 years ago | (#34800962)

To be honest your findings fit my personal point of view and surely has this a major bearing on for example road safety.

I've grabbed a copy of your paper and will have to do a proper digest of it - a quick read shows it to be potentially pretty important in many fields of safety.

Good suff.

Cheers
Jon

PS Its not my thing as such (I'm an IT bod) but it makes a damn good "news for nerds" story

Re:Different kind of change (1)

onionman (975962) | more than 3 years ago | (#34801006)

hi jon, i'm one of the authors of the paper. just thought i'd answer your question about the refresh rate. we used laptop screens that ran at 60 Hz, but the demo works even if you keep the dots motionless and lift up the screen and rock it back and forth. (you can try this yourself if you download the video.) the demo also works on a CRT at 120 Hz. so yes, it the refresh rate was considered and controlled for, and it doesn't seem to matter much. the motion in the youtube and vimeo videos are a bit jerky because they were converted to 30 fps.

Mod this up!!!

Hey Moderators, we have an actual author of one of the discussed stories replying to a direct question in a thread. I think this merits some "+1 Informative" points.

Re:Different kind of change (1)

weicco (645927) | more than 3 years ago | (#34802010)

Naah. He obviously has an agenda is thus biased :D

Re:Different kind of change (1)

cplusplus (782679) | more than 3 years ago | (#34802070)

Since you're one of the authors, I thought I'd chime in and share my experience. I'm partially color blind, and if you put certain reds, greens and/or grays next to each other I have a real hard time distinguishing what's what. I'm not sure how much that affected what I perceived when I watched these.

When I watched the first video with the vividly colored dots, and they started moving, I thought "Huh, I don't get it. I see the colors change. What's the big deal?" My wife, who was watching at the same time, could see very few color changes when the dots started moving. I thought she was just joking, until we watched the grayscale dots. Wow... I could not detect a single dot changing shade unless I cheated and started following them with my eyes. She did much better on that one than I. The shapes one was quite interesting for me. The circles morphed smoothly in to plus signs before they started moving. When moving, they seemed to instantly change to little plus signs (I could not perceive any kind of 'morphing' effect, just instantaneous change).

I'd be curious to know if you have considered how color blindness of varying degrees may affect how these videos are perceived by some.

Re:Different kind of change (0)

Anonymous Coward | more than 3 years ago | (#34802080)

It's simply about your brain tracking the dominant characteristic of an object. As the visual neuroscientist said above, it's about motion overriding other kinds of change. Your brain still perceives the changes other than position, but they're no longer the most important factor in continuing to identify individual elements.

This is obviously an experiment where someone experienced in visual neuroscience could offer you quite a bit of insight on what's already known. Before continuing your research, why don't you get in touch with him? Might save you quite a bit of time poorly re-inventing the wheel.

Re:Different kind of change (0)

Anonymous Coward | more than 3 years ago | (#34802172)

Dude, the authors of the paper are vision scientists at Harvard...they probably know a thing or two about vision and what's already known about it.

Re:Different kind of change (1)

ShakaUVM (157947) | more than 3 years ago | (#34802136)

>>we used laptop screens that ran at 60 Hz, but the demo works even if you keep the dots motionless and lift up the screen and rock it back and forth.

You know this doesn't change anything, right?

Think about it from the point of view from the retinal afterimages left on an observer - if the laptop is moving a dot 1 inch/second on its screen, it will leave 60 afterimages, each spaced 1/60th of an inch apart. If you move the laptop instead, the observer will also have 60 afterimages in the second, also 1/60th of an inch apart. Identical input. The 120Hz CRT used, though, is a better control for that variable, though not perfect. The problem is that if the radius of the dot is smaller than the amount the dot moves in one frame, it will break apart and not appear to be an object in continuous motion but rather a series of discrete dots. This doesn't look to be a problem in your study, though, as the dots all move relatively slowly.

Very interesting illusion, though if you know what you're looking for and set the point of your attention away from the focal point of your eye, you can occasionally notice objects popping. So I'm guessing that the gate-keeping mechanism protecting attention prefers motion over color and shape change, which kind of makes sense, eh?

Re:Different kind of change (1)

LocalH (28506) | more than 3 years ago | (#34800570)

The gorilla illusion isn't universal, either - I successfully counted 15 passes AND saw the gorilla (complete with chest-beating) on my first view. I would wager than a not-insignificant percentage of people could do the same. I would even posit that the set of people who are "immune" to the gorilla illusion would intersect somewhat with the set of people who have high skill at rhythm gaming - both require tracking lots of moving objects.

Re:Different kind of change (1)

JSG (82708) | more than 3 years ago | (#34800810)

Correct, it isn't universal but it is common for people to miss it.

You may have been lucky or you may be gifted - who knows but in this case (ie this discussion) we have two data points - I missed it and you didn't. Now even on /. that is not normally considered proof one way or the other.

Cheers
Jon

Re:Different kind of change (1)

M. Baranczak (726671) | more than 3 years ago | (#34802298)

I got to the video by following a link that said "gorilla", in the context of a discussion of optical illusions. Of course I saw the gorilla - I was expecting it. (Idea for a follow-up experiment: make a video without a gorilla, and convince people that there is one in there.)

Re:Different kind of change (1)

Anonymous Coward | more than 3 years ago | (#34799876)

im having trouble seeing this illusion, i kinda understand what im supposed to see but im not getting that response that is described.

Could that be because im a professional gamer, Focusing on competing in Starcraft 2 at this point in time. When massive armies clash and they have to be microed everything is moving around and changing and requires exact placement and control, Could it be that i simply have become immune to this illusion of not noticing when something is moving?

Re:Different kind of change (1)

JSG (82708) | more than 3 years ago | (#34800026)

Or you are especially good at analyzing computer generated images.

I still hold that this is an optical illusion of some sort, possibly exacerbated by the presentation medium.

On the first vid are you able to see that the dots seem to stop flashing when rotating and you are absolutely concentrating on the central dot?

Cheers
Jon

Re:Different kind of change (1)

LocalH (28506) | more than 3 years ago | (#34800586)

Personally, I didn't see a complete cessation of flashing/pulsating/shapeshifting, although it did seem to slow while the dots were rotating as a unit. I could definitely still sense that the dots were changing independently of the rotation, however.

Re:Different kind of change (1)

damnfuct (861910) | more than 3 years ago | (#34800120)

Nice.. This is how I figured my brain was working. It seemd to be interpreted as some sort of unknown scenery moving behind a rotating plate with a hole pattern in it.

Re:Different kind of change (1)

pseudotensor (1416993) | more than 3 years ago | (#34800258)

Agreed. The "motion detector" in our visual cortex must be swamped by the "true" motion (true defined by movie creator's intentions). I can too point my eyes directly at the center point but still see that the side colors are changing. So it's not that the colors stop changing, it's that the "effective motion" of the colors changing was swamped by the "true motion". Most psychology papers seem naive like this in that they think they tested one thing, while they actually tested something different. Why can't they have the intuition that random slashdot people have?

Re:Different kind of change (1)

MartinSchou (1360093) | more than 3 years ago | (#34800286)

If you pay attention to a given dot while holding your gaze still fixed at the central white point (not as hard as it sounds), you can clearly still see the colors changing.

I agree, I can still see the colours change, when the ring starts moving.

However - to me the apparent speed of change is slowed significantly.

If I move my focus to one patch of the ring, that patch seems to change colour slowly, moving or not. Change the focus, and the previously calm area is now moving rapidly (in my peripheral vision), moving or not.

Once the ring is moving though, my entire peripheral vision behaves as if the speed of colour change has slowed significantly.

Like you, i haven't read the paper attached, so they may have similar findings. I just thought it interesting to share my own experience

Re:Different kind of change (1)

fbjon (692006) | more than 3 years ago | (#34800404)

Though IANAVN, I'm not so sure. Wouldn't that mean that the apparent motion shouldn't be visible during the rocking motion? That seems so in the size-change video (even if it is the least contrasty one), but in the first one there are several groups of dots that have an apparent movement, especially the darker blue "worms". I still see that apparent motion around the donut while they're also moving for real. But most importantly, the shape-changing video doesn't seem to have any apparent motion at all while static (other than the monitor refresh), and yet the perception of change disappears.

Also, does concentrating on one group of dots really count, since you still wouldn't perceive the changes elsewhere in the donut? The participants were instructed to pay attention to all dots.

In any case, to my understanding the explanation in the paper says that the rocking motion of the dots is larger than the receptive fields of the change detectors, i.e. they move out of a field before change can be detected. Seems plausible to me.

Re:Different kind of change (1)

izomiac (815208) | more than 3 years ago | (#34800884)

Technically, the monitor used to watch the video works by apparent motion as well (i.e. 60 Hz refresh rate). Perhaps the optical illusion of apparent motion doesn't work as well with the second iteration. A good test would be to replicate the illusion with physical objects (not that I RTFA to see if they did this).

There'd be an evolutionary advantage to observing the properties of a moving object, so I'd be surprised if we have a lot of trouble with it. Observing the shockwaves in the fur of a moving animal would allow a pursuing predator or fleeing prey to react more quickly to the animal's changes in movement. Jungle creatures would also be at a pretty big disadvantage if wind blowing the foliage disabled their ability to spot something appearing larger as it approaches...

Re:Different kind of change (1)

OnionFighter (1569855) | more than 3 years ago | (#34802046)

I noticed that when I was looking at the unmoving dots, I saw them as individuals. As they started moving together, I reinterpreted them as a single mass made up of dots. It would be interesting to see if the effect is the same when the dots are moving in different directions and at different speeds.

Re:Different kind of change (1)

cavebison (1107959) | more than 3 years ago | (#34802062)

That's exactly what I found as well. I tried to work out what was going on, and noticed that if I did fix my "peripheral attention" on a particular outer circle as it moved, I could detect its changes, and a little of those adjacent to it.

I think also what is happening is that, when rotation begins, many dots are traversing the *same area* of vision while your eye is keeping very still. So instead of the brain "intentionally silencing" change over motion, another possibility is simply that points are traversing previous points' after-images and the brain can't process what's going on and gives up.

So it would be interesting to see if this effect also happens when:
1. The rotation is very much slower
2. Dots are spaced father apart
3. Do it with just 1 rotating dot. Perhaps effect only occurs with several.
4. These are quite subtle changes. Try large dots, large changes.

Haven't read the paper, so just musing. :) But I think this one experiment, on its own, probably doesn't delve into it deeply enough.

That explains (0)

Anonymous Coward | more than 3 years ago | (#34799136)

those idiots running red lights.

captcha: sleepy. Maybe sleep deprived drivers too

incredible (1)

v1 (525388) | more than 3 years ago | (#34799150)

demonstration of how when the brain receives two different associated inputs and determines one is much more important than the other, how well it focuses you on just the important one.

In a predator-prey situation, prey are usually excellent at spotting movement. It's not surprising that when we see something start to move that's a bit dynamic, (like a tiger running through our view among the grass) how our brain "freezes" the image and allows us to process a more static interpretation of it while we track its movement through a visually very noisy environment.

Sort of along that line, after seeing that tiger race through the grass, you'd probably have completely missed the other three just standing there as the tiger you were tracking ran past them

Re:incredible (1)

JSG (82708) | more than 3 years ago | (#34799560)

For [random deity]'s sake please stop the predator/prey bollocks.

For a large part of humanity, being lunched by a sabre toothed donkey has not been much of a worry for a very long time.

So why not couch your argument in terms that are relavent? Have a think and decide how long ago your ancestors would have worried about a tiger (rather than say being nobbled by the local feudal system or disease) and then decide what the "rate" of evolution is.

I'll grant you that the rate of evolutionary change is probably pretty slow - for a given value of slow.

However I still think that the standard language used in this sort of discussion, ie dropping in lines like "well that attribute allows man to spot a predatory sheep advancing across the plains".

Its time the beastiary was updated to take account of cars, trucks and white van man.

Re:incredible (1)

Chris Burke (6130) | more than 3 years ago | (#34800208)

Predators are also frequently excellent at spotting movement. Which is why many prey animals' first instinct when they see a predator is to freeze completely still.

Humans, though, were both predators and prey.

Classic magician's trick. (4, Interesting)

RyanFenton (230700) | more than 3 years ago | (#34799196)

Switching something when it is in the middle of fast movement is the basis of all kinds of slight of hand tricks. There's just a certain state where the mind identifies something just as a blurb of overlapping color, rather than anything processed meaningfully, and you can freely swap it with a similar item without any notice. Mix in basic misdirection, and you can fool almost anyone's expectations. It's also why you kind of have to learn to juggle by feel & pattern rather than just sight - because the hand really does have to be faster than the (mind's ability to process information from the) eye to keep up with the pattern.

Ryan Fenton

Aircraft change size and color? (0)

Anonymous Coward | more than 3 years ago | (#34799256)

Yeah, that's often a problem for fighter piolts... They're about to engage an enemy when all the sudden the aircraft changes size and color. Better update the training manuals right away.

Re:Aircraft change size and color? (2, Informative)

Anonymous Coward | more than 3 years ago | (#34799984)

Decepticons have known this trick for aeons....

Video Links (0)

Anonymous Coward | more than 3 years ago | (#34799260)

Site appeared to be slashdotted. Here are the youtube links extracted from the page:
Motion silences awareness of hue changes [youtube.com]
Motion silences awareness of luminance changes [youtube.com]
Motion silences awareness of size changes [youtube.com]
Motion silences awareness of shape changes [youtube.com]

Damn Scientists (3, Insightful)

flogger (524072) | more than 3 years ago | (#34799264)

As a magician, I have known this for years. Dai Vernon, The Professor [wikipedia.org] , explains that concept the scientists just discovered as a simplistic beautiful statement, "A larger action covers (or hides) a smaller action." Science finally catches up to the magicians.. Damn them. :-)

Buffering... (2)

Bo'Bob'O (95398) | more than 3 years ago | (#34799282)

Unfortunately the video player had no indication that it was not loading at all (likely slashdoted), instead just sits static on the first frame. However, it took me about 30 seconds of staring at the static image wondering if my since of perception was so bad I -didn't see anything moving at all-

Turns out it is pretty bad, just not in the way I thought; I recommend going straight to the youtube versions linked on the article.

It's a pretty neat effect, sort of one of those things that become pretty obvious once you see it.

well... yeah (2)

MobileTatsu-NJG (946591) | more than 3 years ago | (#34799344)

"Scientists at Harvard have found that people are remarkably bad at noticing when moving objects change in brightness, color, size, or shape..."

That may be because our eyes are exposed to so many different lighting conditions that our auto-white-balance is kicking in.

Re:well... yeah (0)

Anonymous Coward | more than 3 years ago | (#34800954)

so why would there be a difference between when the things move vs. don't move? there are always a mix of colors and brightnesses.

Re:well... yeah (1)

MobileTatsu-NJG (946591) | more than 3 years ago | (#34801526)

so why would there be a difference between when the things move vs. don't move? there are always a mix of colors and brightnesses.

When you're a monkey moving through the forest, things are passing by as you're moving in and out of pools of light. Your eyes are trying to adjust to it. That's what the test they showed seem to be testing anyway.. the background was changing luminance while multi colored things roamed about.

Not everybody.... (0)

macraig (621737) | more than 3 years ago | (#34799348)

I'll bet Monk [imdb.com] doesn't have this problem!

Hmmm (1)

Trouvist (958280) | more than 3 years ago | (#34799382)

As a former competitor at the world-level in first person shooters, perhaps my cortex has adapted differently, because when I stare at the dots in the center, I can always tell that the shape or hue or brightness are changing. I can tell when they change and how they change. I can see how in many ways this might be true for 99.99% of the population, but when you spend man-years staring at stationary dots in the center of a screen (crosshair) while "looking around" in-game waiting to notice single-pixel changes out of the ordinary, maybe you learn to notice it?

Not for me (1)

Nebulo (29412) | more than 3 years ago | (#34799452)

I'm surprised to report that this one doesn't affect me; I can definitely perceive that the dots change color, even when they're moving around.

Nebulo

Am I the only one.... (2)

Labcoat Samurai (1517479) | more than 3 years ago | (#34799464)

Who only noticed a *diminished* sense of the colors changing? I could still see the colors changing, it just didn't seem to be nearly as much as before the dots started moving. My experience was as follows: 1) Ok, colors changing 2) dots moving and wow the changes stopped! 3) oh wait, no I'm seeing a few changes still....

Re:Am I the only one.... (1)

The End Of Days (1243248) | more than 3 years ago | (#34800842)

That's what I saw. I put it down to knowing what effect they were trying to produce.

Re:Am I the only one.... (1)

deapbluesea (1842210) | more than 3 years ago | (#34802094)

In true /. style, I watched the video without reading anything else. As I was staring at the colors changing, everything started rotating so I focused on the center dot, wondering what was going to happen next. As I did this, I lost all perception of color changes and only saw the motion. Sooooooo, either I'm not a world class gamer like Trouvist [slashdot.org] , or the affect was pretty much as reported by the researchers. I'm gonna go with option b on this one.

Re:Am I the only one.... (0)

Anonymous Coward | more than 3 years ago | (#34802578)

Look closer.

The dots actually stop changing color for a bit when the rotation starts.

I think they studied something a little too obvious, didn't find anything remarkable, and tried to pull some optical illusion videos out of their ass.

On a similar theme... (1)

Twinbee (767046) | more than 3 years ago | (#34799582)

Nice illusion indeed, and at least partially new. A while back, I combined two different illusions to make a single more effective illusion. I wonder if there's any connection with the one in the news article as they both seem to rely on the movement of peripheral vision confusing other aspects of change in peripheral vision:

http://www.skytopia.com/project/illusion/ipage-vb.html [skytopia.com]

The effect this one achieves is the disappearence of visual areas rather than 'merely' lessening the effect. Although mine is arguably more dramatic once it happens, it can be slightly tricky to see the effect immediately compared to the one in the news article.

obligatory (1)

$0.02 (618911) | more than 3 years ago | (#34799590)

Nothing to see here move along

Seems logical (2)

Leon Buijs (545859) | more than 3 years ago | (#34799636)

Because in a primitive, hostile environment, the main thing is to see the enemy / victim coming. That's one of the reasons why people keep watching anything that moves above static parts. That it also changes color.. well.. big deal. Noticing it moving is much more important.

Re:Seems logical (1)

houghi (78078) | more than 3 years ago | (#34800184)

If it is about enemies, then you would see changes where you not focus better.
Hunting is another thing, as you will be focusing on one target.

Seems logical. Hunting would be a daily thing to do, war not so much. It is not as if they were at war all the time.

Did they also notice... (1)

bickerdyke (670000) | more than 3 years ago | (#34799734)

...that our brain is really great at recognizing objects despite changes in "brightness, color, size, or shape"?

Prior art? (1)

houghi (78078) | more than 3 years ago | (#34799836)

This is from 1999. http://www.youtube.com/watch?v=vJG698U2Mvo [youtube.com]
Many of you might already know this, but this is the original.

It is even used in an add against cyclist(1) http://www.youtube.com/watch?v=Ahg6qcgoay4 [youtube.com]
A much more interesting one is to be seen at http://www.youtube.com/watch?v=W92tDI4RYCw [youtube.com] Almost the same difference.

(1) You are to hit them and not miss them. At least that is what I get as message.

Counter-claim: Their examples are bad. (1)

Anonymous Freak (16973) | more than 3 years ago | (#34800018)

In the example videos, the changes are not random, they are a pattern that rotates around the group. (Watch the shape change and size change to see it most obviously, but it's there in the color/brightness ones as well.)

So when the group starts rotating, it is actually counter-balancing the individual item change. You're losing sight of the trees for the forest.

Example: a group of people are on a merry-go-round. Each one is holding paper with a symbol on it facing up. They start passing their papers around counter-clockwise. So each person's "symbol" is changing. You see it happening easily. Then the merry-go-round itself starts rotating, which counter-balances the rotation of the moving symbols. Even if you quickly reverse the merry-go-round motion every so often, as they do in their examples, you will see the 'overall pattern' seem stationary, followed by VERY QUICK movement, followed by stationary.

A better example would have each individual item's changes be completely random, not following an overarching rotating pattern.

Um, just try Brain Academy on the Wii (0)

Anonymous Coward | more than 3 years ago | (#34800056)

It's got one test where there are 4 animations, and you have to pick out the one slightly different. It's quite difficult!

How would squids see this? (4, Interesting)

k2backhoe (1092067) | more than 3 years ago | (#34800172)

The reef squid has the ability to quickly change colors and patterns on it's body, and seems to signal other squids in this fashion (as well as for camouflage). I wonder if they would be fooled by this illusion or if their neural optics are wired very differently than ours. It would be challenging to try to create an objective test that you could do with them.

This is Relevant to Me (3, Interesting)

PlaneShaper (1830294) | more than 3 years ago | (#34800352)

I won't necessarily claim to be one here, since anyone can claim anything on the internet. But I wonder how well experienced MTI analysts (http://en.wikipedia.org/wiki/Moving_target_indication) would perform against these videos. Quite literally, it is the job of an MTI analyst to distinguish coherent from non-coherent changes across a vast number of moving dots displaying all sorts of crazy behaviors.

Additionally, I would prefer to see this experiment run under different conditions, such as having the videos begin with dots in apparent motion for many seconds, then having them stop moving. I do think the results of the experiment are damaged by having the motion segment (3 secs) be significantly shorter than the non-motion segment (5 secs) and always happening after the eyes and brain have adjusted to the lack of apparent motion.

I think another big problem with the videos provided is that the motion segment alters direction 9 times (counting first and last) within a short window -- this may not result in the human mind having difficulty seeing change in moving objects, but a difficulty in adjusting the perspective of the total scene to something observing rapid fluxuation in velocity. (I.E. The circle constantly rotates back and forth, preventing the brain from "getting used to" the scene, whereas when the dots are stationary and only changing in specific property, they remain in this configuration for a much longer period of time).

It's a interesting topic, but research could have focused more on overall configuration of how viewers were presented with the experiment. There isn't enough information present to draw an accurate conclusion from these observed results.

Depends on relative frequency of both events (2)

hardtofindanick (1105361) | more than 3 years ago | (#34800456)

It seems to me that this is a fairly simple illusion: the frequent event is "more interesting" hence the brain focuses on that. Color change in this example is happening slower than rotation hence motion is favored instead of colors.

Environmental Adaptation (3, Funny)

517714 (762276) | more than 3 years ago | (#34800468)

Maybe if our ancestors had fed on flocks of fast moving chameleons we would be better at this.

I suspect... (1)

wonkavader (605434) | more than 3 years ago | (#34801130)

I suspect that this is an optical illusion triggered because the brain is trying to match items by color and size. When color or size changes, the brain matches the wrong blob (which hasn't changed, or just happens to have changed to what the other one was, or to something closer to what the other one was than the other now is) to the original item.

I'd like to see a video with just the fixation point and one datapoint in the periphery. If we still lose track of shape and color changes then that will be harder to explain and more interesting.

I'd also like to see the same multi-blob video done with everything changing in the same way at the same time. I suspect the result would be the same as the one-blob video condition.

Not that this isn't a neat demo as is. I'm just hungry for some more conditions.

stupid scientists (2)

perryizgr8 (1370173) | more than 3 years ago | (#34801154)

instead of making a video, couldn't they have made a flash thingie, so that you could change the parameters of the illusion too? maybe we could then tell at what rotation speed color change becomes hard to notice.

Re:stupid scientists (5, Interesting)

suchow (1972574) | more than 3 years ago | (#34801370)

hi, stupid scientist #1 here. (i'm one of the authors of the paper.) you're right, it would be nice to have a flash app that lets you change the speed of rotation. sadly, i programmed everything in MATLAB and I don't know flash. (and hey, didn't our overlord already pronounce flash dead?) on that note, if anyone knows flash and wants to program this up into an interactive demo, send me a message, i'm sure we could work something out.

but you're in luck, my friend. the demo works even if you pick up the screen and rock it back and forth, and i have a movie (link below) with no motion. you can loop the video and whirl the computer around all you'd like, at various speeds.

here's the movie [jwsu.ch] .

as an aside, the first experiment in the paper in a speed manipulation. (spoiler alert.) the fast the ring rotates, the slower the dots seem to change.

I call shenanigans! (1)

TheABomb (180342) | more than 3 years ago | (#34801236)

The video directs the user to state at a stationary object (and even then it's not hard to notice some progression). If you actually look at the moving objects (you know, like the way people who aren't undergoing the Ludovico Technique normally look at stuff), it's quite easy to notice what's going on.

Not if you look at them... (2)

llZENll (545605) | more than 3 years ago | (#34801854)

"people are remarkably bad at noticing when moving objects change in brightness, color, size, or shape"

I think you left out an important qualifier:

people are remarkably bad at noticing when moving objects change in brightness, color, size, or shape IN THEIR PERIPHERAL VISION

If you look directly at any of the moving objects you can see any of them change in brightness, color, size, or shape. Your peripheral vision is not your focus for good reason, and of course its not going to track every single change like at the center of your focus of vision, its not supposed to and is better that it doesn't.

Culture Bias? (3, Interesting)

Arterion (941661) | more than 3 years ago | (#34802244)

I'd like to see if there's a culture bias to this. Get someone from a very non-westernized culture and ask what they see. They're regularly not fooled by these kinds of "illusions":

Which line is longer:

>----------

Their eyes just aren't trained to see geometry the same way as westerners who are faced with tons of man-made things everyday.

Old News. (0)

Anonymous Coward | more than 3 years ago | (#34802394)

I remember watching a documentary 5 years ago which focused on this phenomenon, showed some practical examples too with driving safety and magic tricks.

I see all.... (1)

David_Hart (1184661) | more than 3 years ago | (#34802416)

When looking at the video I see all of the color changes, even when the ring is in motion. Then again, I am also one of those who can see the cycle rate of flourescent lights. Perhaps my eyes are hyper sensitive or have a higher bandwidth path to my brain than most people. I was in Vegas in November and saw the David Copperfield show and was in the front row. I was able to see the slight of hand that was being used to swap objects and figure out how he was doing the tricks. Made it somewhat boring for me, but my sisters enjoyed the show.

temporal memory (0)

Anonymous Coward | more than 3 years ago | (#34802484)

We learn about an objects characteristics when it changes through time. The reason why an infant would rotate an object in his hands to see all its facets, is to record it in its mind and learn that it is indeed one object by connected still images at t seconds with the one at t+1 seconds. It is the difference in rate of change of visual feedback that enables us to distinguish between objects in our sight. It is entirely possible, that during motion, our brain engages a learning process and thus suppresses the ability to distinguish between still images of the time slices during motion

Effects of study on user interfaces, games (0)

Anonymous Coward | more than 3 years ago | (#34802688)

Curious what effects the results of this study would have on user interface and game design.

Especially with games I can be quite focused on one area of the screen, and do not notice a blinking icon in the corner. Game and user interface designers may consider different ways to visually notify the user of something, that are harder to miss.

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