AMASE: Why Do We See Stars?

[Joanne sitting in a chair in an office.]

Joanne: Welcome to today's episode of Ask Me Anything: Science Edition! 

[Cut to University of Guelph Logo and slogan: Improve Life.]

Joanne: Today's question comes to us from Cameron! 

[Cut back to Joanne in the office.]

Joanne: A grade 6 student in Brampton Ontario.

[Cut to Cameron, sitting on a bed.]

Cameron: Hi. I have a science question. Why do we see stars when we get hit on the head?

[Cut to Joanne in the office.]

Joanne: Unfortunately, I have absolutely no idea the answer to that question, so on to the next question. No just kidding. I don't know the answer to the question, but I know someone who does. So, I'm going to phone a friend and that friend is Jay Ingram.

He is the former host of The Daily Planet on the Discovery Channel. He is the former host of Quirks and Quarks on CBC radio, and he's written a bazillion science books, the most recent a series called The Science of Why. So, let's call Jay.

[Joanne’s frame shrinks, to allow Jay’s to appear beside her.]

Joanne: Hi Jay.

Jay: Hello. So, Cameron's question is a great question. And to answer it you have to know a little bit about how we see, because even though our eyes are the things that we see with most of the brain work that goes on to kind of understand what we're seeing as we look
around the room is done here. 

[Jay touches the back of his head, just above his neck.]

Jay: It's a place called the visual cortex. It's at the back of the brain. 

[Jay’s frame moves to take up the whole screen.]

Jay: So, all the messages, all the information from your eyes has to travel all the way to the back of the brain where it's analyzed.

Now, why do we see stars. Let's say you're, I don't know you're in the kitchen and the cupboard door is open and you don't know that and you bang the back your head into the cupboard door. Well, it hurts but also for a few seconds you think you're seeing stars, but what's happened is, that place at the back your brain that is so crucial for getting vision going has been jarred by that impact. Either the brain hits the back of your skull or it's just the sudden movement of your brain in your skull and that impact causes the brain cells back
there to become active for a few seconds.

Now it's not what you're looking at that they're becoming active but they're just sort of spontaneously bursting into activity and so you get these little points of light that you see and then they fade away and then you're fine. 

[Jay’s frame shrinks and Joanne’s frame appears beside him.]

Jay: There's another way of doing it where you can actually involve your eyes and I'm going to show you this but you've really got to be careful doing it.

All you have to do is take your fingers and push very gently. 

[Jay demonstrates, putting the first two fingers of each hand each eye. Joanne does the same.]

Jay: Not hard! Very gently on your eyes, preferably both. 

Joanne: Okay

[Joanne’s frame fills the screen.]

Jay: And if you wait for a while you start to see patterns of light. 

[Cuts to Jay’s frame full screen.]

Jay: Sometimes little crisscross things, sometimes waves of light moving around sometimes... 

[Cut to Joanne, full screen.]

Joanne: Little blue dots.

Jay: Yeah, yeah exactly.

[Cut to Jay full screen.]

[Cut to two frames showing both Jay and Joanne.]

Jay: You've got light-sensitive cells in your eyes, that's how you see. By pressing gently on your eyes you're doing the same thing as hitting the back of your head you're activating the cells in your retina. What's their job? 

[Cut to Jay, full screen.]

Jay: To report to the back of the brain that they've been active. Well, they're active because they're not seeing light in this case, they're active because you've pushed on them, but they nonetheless send messages to the back and again you see stars.

[Cut to two frames showing both Jay and Joanne.]

Jay: Not just stars though, as I pointed out you see colours, you see patterns, you see crisscross, all kinds of fantastic stuff.

[Cut to Jay full screen.]

Jay: It's even been said that if you're just alone in a dark room you might spontaneously start to see these and for people, for prisoners, let's say in solitary. If the lights are off this has been called the prisoner's cinema, because it's about the only thing they can see.

[Cut to two frames showing both Jay and Joanne.]

Jay: Now so that's why you see stars but let me give you to kind of cool off shoots from this. 

[Cut to Jay full screen.]

Jay: One is that cave paintings, 30,000 years old, most of these are in France and Spain in caves, literally. 

[Cut to two frames showing both Jay and Joanne.]

Jay: The people who painted these they painted beautiful images of humans and animals and sometimes they apparently took their hand and blew paint threw their hand to
leave an imprint of the hand on the wall.

[Cut to still image of cave paintings.]

[Cut back to, two frames showing both Jay and Joanne.]

Jay: But there are also lots of places where these stars, technically they're called phosphenes. There are patterns like them on the cave walls and people looking at this, archeologists, think you know maybe they somehow stimulated their brains, probably not by knocking their head on a cave wall, but somehow created these patterns and then painted them directly on the wall.

[Cut to Jay, full screen.]

Jay: We'll never know of course that was 30,000 years ago but it's a pretty cool idea, but coming up to today one of the really interesting things that scientists are trying to do is help blind people see.

[Cut back to, two frames showing both Jay and Joanne.]

Jay: By stimulating the back of their brains electrically to create stars and trying to do it in a way that if you can arrange them, you can create letters. 

[Cut to Jay, full screen.]

Jay: Like letters in the English language, any language, and they've had some success, it's very, very, early but some success with one patient where she was actually, able to make out letters.

[Cut back to, two frames showing both Jay and Joanne.]

Jay: Just because they were happening to stimulate exactly the right parts of the back of her brain to create stars that would line up to make like a letter L, or a letter A or whatever. 

[Cut to Jay, full screen.]

Jay: So, it's very early in the game for that but these stars that you get when you hit your head may actually have some practical application for blind people.

[Cut back to, two frames showing both Jay and Joanne.]

Joanne: Cool. Awesome. Well thanks Jay.

Jay: You're very welcome and thanks Cameron great question.

Joanne: I think I may have overdone the pressing on my eyes thing a little bit cuz, I'm still kinda seeing them...

[Cut to Joanne, full screen.]

Joanne: There you have it, now you know why you see stars when you get hit in the head and if you want to learn more make sure you pick up a copy of Jay's new book The Science of Why 5 coming out later this fall.

[Mara, runs in shouting and hits Joanne in the head with a white board.]

Mara: Mommy, mommy! Oh, sorry mom. um thanks for watching Ask Me Anything Science Edition and if you have any other questions just let us know. Mommy are you okay? Bye! She's good, she's good...

[Cut to Guelph Physics Logo.]