How much of what you see is a hallucination? - Elizabeth Cox 

Download a free audiobook version of Oliver Sacks' "Hallucinations" here: adbl.co/2Kpt43k! Thanks to our partners at Audible, every free trial started with this link helps support TED-Ed's nonprofit mission.

"she was completely blind." That really got me wtf

The animations were one of the best I've ever seen

Mom: WHICH ONE OF YOUR FRIENDS CONVINCED YOU TO TRY LSD??!? Me: uhh, TED-ED

Rosali just vibin in her chair when suddenly she starts tripping

I think it's so freaking impressive how ted's animations reflects to the storyline. Well done!

I felt like it was an episode from Adventure Time.

"she was completely blind." *jazz music stops*

Really makes you wonder, if our brain fills in a lot of our vision with stored info, what in real life are we actually seeing and what isn't actually real?

Lack of sleep definitely causes some hallucinations

once i started playing tf2 at around 11am and passed out on my keyboard at around 4am and when i woke up at 11am i could still hear the explosions and bullet fire of tf2, until i remembered i lived in south sudan and those sounds werent hallucinations

The animation is AMAZING. As an artist, I appreciate such great endeavor for creating a visual environment for education to happen at it's very best. Salute to the director.

Ever had that hallucination right after you woke up, that you're holding your phone in your hand, but then you open your eyes and realize you're actually holding nothing?

When the narrator, Susan Zimmerman, said Rosalie was completely blind, with the build up of Rosalie seeing those real-life crowd of circus performers burst into her room, that just blows my mind! That's what I called a plot twist!

Why doesn't the animator remake sonic

I’m now remembering the time a few years ago my clothes crawled around on my floor for a few days and I heard someone breaking down my door and terrorizing. May I never relive those days of my life again.

The cuteness of the hallucination lill guy kinda makes me want to hallucinate just to maybe see it

Well, we will fix this bug in the upcoming update

It's quite amazing and surprising that someone who is blind since birth can distinguish colors in their imagination. Yes, they may know the basic colors but having knowing how red is different from blue is another matter.

This was a great talk! ♥ *I was really surprised, however, that you didn't mention the fact that no blind person has ever been diagnosed with schizophrenia.* To me, that's perhaps the most fascinating part, especially since the most common form of hallucinations for those suffering with schizophrenia are auditory. P.S. since everything we see is subjective, and is all experienced in the brain (for instance: how colorblind people see the world differently), isn't it technically _all_ a hallucination? :)

The brain is so underrated! A lot of people would be fascinated if they’re told about the subject in the right way. Thanks so much TED-Ed :D

Comments: 90% GOOD ANIMATION 9% Justin.Y 1% *DEM DRUGZ*

I think this explains why whenever I walk in the dark, with little to no light, I can see glimpses of obstacles in my way, even though I'm completely aware that there are none also, gorgeous animation as always :D

I sometimes hallucinate voices when I’m waking up. A couple of days ago someone said ‘carpets’ and I woke up. I live on my own but he voice was as if someone said that standing next to me. I know it was a hallucination. I find that in dreams otherwise you don’t really ‘hear’ voices, you know almost the same way as reading off of a page what the other person has said. The voice that said ‘carpets’ was also distinctive away from my own voice and louder than my inner monologue.

My grandma has this... Thank you Ted-ed for making this video, it helped me understand a little bit more what my granny is going through.

Once I got a fever of like 103 and I experienced hallucinations that made me feel like I was shrinking and growing, and to avoid feeling like I was totally gone, I had to grab a large object such as a pillow and curl into a ball around it

I've tried LSD a couple times and asked myself "why does every human beeing have such a different personality?" I came to the result that everyone has another perception of "their world" and this has been influencing their attitude since ever. So our way of perception determines who we are. This is what defines us as an individual, I believe.

5:15 that circle was someones head

I thank you for the content and for this topic exactly because my mother suffers from this syndrome, and when she was telling me about her seeing loud colors, I used to accuse you and say that it is just hallucinations, but now I really understand it makes us respect the difference in our perceptions Thank you for the topic TED

How to locate the part where your eye is "blind". 1- Look straight forward, at a fixed spot, toward the horizon, 2- Close your left eye. 3- Extend your right arm and give a "thumbs up" to the horizon. 4- Move your extended arm to the left, keeping the thumb aligned with the horizon. You'll see there's a spot you can't see your thumb at all. Try moving it. It's like it's not there! That's where your retina cuts out and the optic nerve begins. It's around 10-15 degrees horizontally to your focal point and it is effectively a blind spot. It's where your brain interpolates the surroundings so you don't see a gray spot all the time. The brain also does this somewhat to your nose and eyeglass rims, if you use glasses. I used to wear thick rim glasses with relatively small lenses (I don't anymore. PRK surgery is awesome ♥). And you don't notice them consciently after using glasses for a long time, even though you're well aware of your deficiency.

I don't know if I'm the only one, but I would feel absolutely terrified. What if you start hallucinating scary demons and devil's and creatures? You wouldn't be able to stop it, it would be too real. I'm sorry for anyone who has this.

TED-Ed really makes me question the world and I love that

This art style is so calming. I just feel alive for once more.

Beautiful animation! Kudos to you, animator!

The reason the blind spot never bothers us is because we have two eyes. They each have a blind spot in a different place, so they both fill in the other’s blind spot.

This video is beautifully put together. Not to mention the descriptions are the most accurate and simple I have ever heard.

When I had a fever, I had hallucinations. At the time I thought it was my brain taking the easy route to showing me what I was looking at. It was kind of an imaginary focus. I guess this video confirms it!

I hallucinate sounds even though I still have my hearing, some of them were calling names even Unknown songs

TED-Ed be making better plot twists than M.Night Shyamalan

The writing and animations were fantastic for this video. I got the feeling there was well grounded thought behind each line of this video. Fascinating topic.

Everything is gorgeous, from the sound effects to the visuals. And the explanation is clear and well put out. You never cease to amaze me!

Q) What causes hallucinations? A) Our Brains, that what.

Ted ed is becoming my favorite thing to watch on youtube. These animations, just wow. Especially when under influence, absolutely mesmerizing.

The animations just so smooth and so fluent… it’s beautiful

I've always loved TED-Ed's animations but this one was especially brilliant!!

The animations are amazing!!

"We can pool information about experiences, but never the experiences themselves. From family to nation to every human group is a society of island universes." -Aldous Huxley, The Doors of Perception

This video is so visually appealing and calming. Great info as well, thank you!

The animation was mesmerizing, ABSOLUTELY BEAUTIFUL!

having psychosis I can tell you the anti psychotics really work wonders I was extremely paranoid of them at first but when I changed to the monthly injection it really allowed me to step back from delusions and hallucinations and I felt like a whole new person. they come with a few side effects but its definitely worth it if your life is out of control and I can tell you they also really do effect how lsd works. I took some on a holiday with a friend and even after a few tabs It didn't have that much of an effect beside the body load and having a great sense of humour while my friend was really enjoying his trip. hallucinations can be interesting and fun but in every day life they can get in the way and the delusions can really break you down, if anyone is experiencing voices or thinking people are talking in code or the tv is talking to you these can be signs of psychosis and its ok to get health care involved because if it gets worse its hard to trust anyone including your own reality.

I thought this was going to be about drugs and I was already typing a joke about it and you dropped that « blind people have hallucinations » and my mind was bloooooooown!!

nobody, absolutely nobody: fever dreams:

What an interesting topic. As a person with a lot of experience with hallucinogenics you really begin to understand how subjective the world really is. When you are able to identify when you are hallucinating it can be a pleasant experience but if you cannot it is very terrifying, I can only imagine life with schizophrenia.

I'm gasping at every single frame, the animation and transitions are gorgeous

This is so beautifully bade and so incredibly cute! filled me up with inspiration and need to create! thank you!

One time i was trying to go deep in meditation and i thought i sleep but i was awake, and I don't get any visuals that are more normal but i was hearing and controling a whole orchestra, i was hearing every instrument and i was able to focus on then individually, i never have heard this song that was playing, it feels like i was creating the sounds all at same time, it was beautiful

Every trip can be a bad trip depending on how you perceive it. I've been in a room full of people on LSD and we all seen the same exact thing. Or the same exact thing happened to us during the trip that seemed to stand out from the rest of the trip. I believe it lifts a vail of what normal perceiving people see. I also had a near death experience and was completely Atheist "Never religious in my life" before this happened. I saw my entire life "Like a movie" play out in front of me. Then I was shown a baby sitting in the middle of the bed with her arms out wearing a ponytail on the top of her head. Then I awoke looking down on myself from an aerial view staring down at my own body. I couldn't see or feel my body from where I was. I only had my thoughts, my sight, and my hearing. I could hear people from below me frantically trying to revive me. I felt calm, warm, like a baby being cradled by it's mother. I was slowly drifting upwards ever so slightly as the seconds past. I asked questions in my head and they were all answered. I was eventually revived and a year later had a baby girl that looked exactly like the little girl from my "Life review". The whole time I was floating I felt as if someone was next to me but I was never able to turn to see who it was. I knew from that moment there is more to this world than we could truly ever understand. Almost feels futile sometimes. Especially to explain it to others. Near death experience studies are fascinating. Seems to hold a lot of keys to the answers of consciousness and the human brain. I was experiencing thing I shouldn't have been experiencing in a time when I should not have been conscious at all. I was dead for 15 minutes.

The animations are amazing as always!

Boy: granny can you see me? Granny: wow mr. Triangle you can talk, Boy: I’m your grandson. Are you hallucinating

I have always wondered about hallucinations and I was so happy when I so a Ted-Ed video about it. Thanks. And the animation is just BREATHTAKING espasily 2:53 . You are amazing.

Thank you for making this video as trippy as possible.

CAN YOU BELIEVE HOW LONG IT TOOK TO MAKE THE ANIMATION.

I can confirm, I've had a lot of hearing issues over my life and I hear all sorts of strange auditory hallucinations.

One of the best videos visually and informative . Loved it

I highly appreciate how this animation is done and how it communicates things.

TedEd is the best . It's so helpful and informative. I love watching this channel. Thanks to all the people who make the animations and do voice overs and do the research themselves. We are grateful❤️

I am a teenage deaf girl who is on RU-vid a lot and you have just help so much as I have had hallucinating voices. Thanks for letting me know what was happening. Yours sincerely a teenage deaf girl👂

the animation and selection of audio bits was superb

The animations were exceptionally well made and presented so well

When you look at a mirror in really dim light, almost all of what you see is a hallucination.

Not here to encourage drug use, but I believe psychedelics, when used properly and with respect; can be a very positive, introspective and meditative tool. LSD, DMT, Ayahuasca, Psilosybin, Peyote- all hold a place than can benefit us when used in a way that promotes insight to the world around us. The concept of an 'ego-death' is, in the moment, often scary, awful and profound; but when you come back to a sober state, it allows you to reflect and feel humbled, almost. Able to see things in a new light and hopefully gain new respect for things you may overlook in daily life. You see details you never would have noticed. Feel things that you may have ignored otherwise. Often times, people generally go back to a child-like state of understanding. Not in a 'childish' way necessarily, but in that your perception changes to see things fresh and in a new light. One you may have never considered before.

1:37 THIS WAS SO SATISFYING TO WATCH-THE NOISSEEE

one of the must clear and beautifully explined videos thanks

What causes hallucinations? them drugs

2:16 Maybe that's the reason for dreams

The sound effects are phenomenal

Can we just take some time to admire how fluid Ted-Ed's animations are while managing to deliver a perfectly understandable lesson to the viewers. Impressive.

I feel that the video is a Hallucination

I had only one auditory hallucination when I was a kid. I was by myself and remember vividly being alone in a park near my house. I heard someone whisper in my head and I immediately looked behind me to find nothing. I don't know why it happened, now I only have these occurrences in the twilight zone of sleep, but it was as clear as any voice I've heard. And I'm positive it was in my head as no trees or places to hide to were around. I wonder if I conjured up this memory but it couldn't have been the case, As I remember every detail to the letter.

The anamations and explanations are amazing

I've always been too afraid to take hallucinogens but I remember a few times hearing such real classical music while I was trying to fall asleep. It lasted for 5 or 10 minutes. There's no rhyme or reason for it. Great video!

It was the day before my 9th grade result of BOARD exams and I was so much stressed out it literally was nerve racking at last I finally slept at 🕝 two thirty n then I woke up at five to Offer prayer (I’m Muslim) and I clearly remember that I was standing and due to extreme sleep deprivation my eyes just closed themselves and I literally saw the same scene but everything was dark mustard in colour and I also saw three to four ME(S) standing on my either side and then I subconsciously say in my mind NOW WE ALL ARE GOING TO PRAY TOGETHER and then I open my eyes just at that moment all of the other ME(S) fuse with me ...I was so scared I immediately finished the prayer and then went to 🛏 bed !!!... I remember that vividly for sure... As a side note I scored 97% ( not bad though) Also I’m myopic but wasn’t born with it Does it mean I have C.......?😱

"Even..Kermit the frog?"

4:56 this part of the animation is so cool idk why

when they said, "she was comepletely blind" that creeped me out tho

The animation is just amazing. So artistic, I'm in love!

3:17 I've experienced the effect of surfaces breathing while falling asleep many times.

can we just appreciate the beautiful artwork and animation. good job animators!!

It is so scary that the possibility exists that one day we just went blind and have been hallucinating since then. This is pretty similar to the Lucid Dream theory where we might have just entered a lucid dream one day and we are just dreaming right now. How disturbing.

I have no problem volunteering for your lsd/psilocybin research!:) #SignMeUp #GreatVideo

The green head character is so cute

what a wonderful animation, I loved how this is not just a vectorial animation, rather this has ( on purpose i believe ) pixel imperfect lines

Once again an impressively good video from one of my faovorites channels. Don't stop making this content cause I won't stop appreciating it !

The animation was incredible and fascinating! Really cool video

3:43 *My last brain cell before a test*

The animation and information was quite beautiful well done

The animations is just pure gold

Top notch animation and great content as always! Keep the good job Ted-ed!

A lot of times I “hear” my dog moving in her crate, even tho she is outside. I hear those little sounds all the time, so I guess my brain just is used to it lol

This videos animation was amazing!! I especially love the elephant at 00:20 !