The Projector Illusion | EVERYDAY MYSTERIES

Have you ever seen a blur of color when looking away from a projector screen? Or noticed how flashing lights look different colors when you move your eyes? This is an everyday mystery! The answer lies in persistence of vision and how your brain processes what it sees.

If you liked this video check out these:
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Creator: Dianna Cowern
Editing: Jabril Ashe and Dianna
Research: Dan Walsh
Thanks to: Wren Weichman and Kyle Kitzmiller

Resources:
Neural response changes during saccadic motion
Brain discards lots of information during saccadic motion, more than necessary
Chronostasis

The PBS Survey is now closed.

[chirayubhatt]

2:22 " Adults will call them observations, I call them clues" 😂😂😂

[CaryKelly]

What I learned:
1) Projectors lie
2) Videos can cause siezures
3) Physics Girl has pretty eyes

[physicsgirl]

Something else interesting to try: watch 0:29 at different speed on your YouTube player. Like 0.25x or 1.5x speed.

[mrsrunningmommy]

Wishing Dianna a full recovery. I have been rewatching her lovely videos as I send her well wishes. We love your way of teaching us “cool stuff “ Dianna! Hang in there🤗

[FelipeFigueroaG]

Tip: if you are watching this on a computer, you can pause the video and use the ", " and "." keys to advance/rewind the video one frame at a time.

[JordanLanePhoto]

A similar effect happens when you look at a spinning ceiling fan. The blades appear to stop for a split second when you move your eyes around.

[sdrawkcabdaernacuoy]

Stopped clock illusion! I've always wondered about that, so thanks for the explanation! I am glad that I am not the only one that has experienced this.

[diabolicallink]

I remember seeing this the first time back when I was in second grade. I was bored and looking at a white computer screen, I started looking around and noticed that I saw red green and blue, I was blown away.
This was before I knew how screens worked.

[hypercube]

This counts as studying for science, right?




Yeah, I think so.

[matts]

I have noticed the behaviour relating to intrasaccadic perception while looking at wheel rims in motion. When spinning they appear blurry, but in the instant I look away, there's a fraction of a second where the wheel appears clearly and I can make out the shape of the wheel rim.

I always wondered about the mechanics behind that, so thanks Diana!

[heylol]

Physics girl you are the best and I love your content

[infomaniac]

I love videos about this stuff. I'm 33 years old now and I've been playing with this stuff since I was like 8. I've seen blue-sky sprites, floaters, ghost hands, after-images. You name it and I've probably seen it. Any content that mixes physics and psychology/neurology always catches my eye.

[PikaPetey]

Yeah this has bugged me for a while. All the time in school and any time a projector is used.

[dalebewan]

I do love PBS Space Time, but you're a lot more fun to watch. The passion you have for the stuff you're talking about is almost contagious. I'm about to start allowing my daughter (7) controlled access to YouTube, and yours is absolutely one of the channels I'm hoping she'll enjoy.

As for #EverydayMysteries - perhaps you could do something on fluid dynamics and brownian motion as they relate to the cool patterns you get when mixing milk in to coffee, juice syrup in to water, or other such similar liquid mixes.
Another (although maybe too close to this one since it's perception related) would be how 3D visual tricks like "holograms" or those 3D postcards/greeting cards actually work.

[humanoidmodel]

Never noticed how nice your eyes are before. you have central heterochromia!

[roadfart]

"WARNING: This video may potentially trigger seizures for people with photosensitive epilepsy. Viewer discretion is advised."

Enters full screen mode...

[Frosty-ojhw]

Worth commenting that projectors give this "rainbow effect" when they use DLP technology, this is a wheel inside the DLP projector that spins and flickers primary colours in front of the lamp rapidly. Some people can see this effect really easily and others cannot, if you are susceptible to this effect then you can buy LCD projectors which do not work in the same way, LCD projectors combine light from 3 different LCD panels which never sync problems with colour meaning you never get the rainbow effect. LCD projectors however can be a lot more expensive so it's best to test with a real projector if you're susceptible to the rainbow effect or not before you buy.

[joeytje]

Usually I press like on a video when I feel like "damn, that's cool" at the end of the video. This video earned the like well before a quarter. Blowing my mind with the flashing of red, green and blue to make a rainbow, AND promising to explain the weird things that happen when you move your eyes away from a white screen? Awesome video already at 1:35 where I paused it to write this comment.

[Sam_on_YouTube]

Hard to compare with SpaceTime. You do mostly classical physics and he does mostly astrophysics. His target audience is a little more knowledgeable than yours so it doesn't really seem fair to compare. Both great channels though.

And if you don't know her, Looking Glass Universe does the best quantum mechanics videos. Fans of Physocs Girl and SpaceTime should DEFINITELY check her out.

[palharley]

You can go frame by frame using the < > keys (aka the comma and period keys) on a keyboard after using the spacebar to pause. very cool to see the color order.