For all you who played Duckhunt.

[YellowMaranello]

http://www.straightdope.com/columns/010511.html

Dear Cecil:

A friend and I were playing Nintendo, the original eight-bit system, and we played Duck Hunt, a game that requires a "light gun." I was wondering: How exactly does the Nintendo game "know" where you are pointing the gun on the screen when you shoot ducks?!? Very mind-boggling! --Matt

Cecil replies:
You're going to give yourself such a smack when you hear this one. Stripped of the high-tech accoutrements (by 1980s standards, anyway), it's the oldest trick in the book. You think you're using the gun to shoot at the TV, right? But really the TV is shooting the gun.

Here's what happens. You shoot at a duck, which appears on an ordinary TV screen. The gun is connected to the game console; pressing the trigger blackens the screen, then causes a duck-shaped white target to appear momentarily. If your aim is true, a photo sensor in the gun detects the shift from dark to light, and bingo--dead duck. In short, the TV emits the light pulse and the gun detects it, not the other way around.

For technical details, see www.howstuffworks.com/question273. htm, which includes a link to Nintendo's 1989 patent on the technology. The patent explains how the dark-to-light shift prevents you from cheating by pointing the gun at a steadily shining light source, a weakness of earlier light guns. You'll also learn how multiple targets can appear on the screen at the same time and how more advanced systems can indicate on the screen exactly where your shot "hit."

But that's for the gearheads. At the Straight Dope we're more interested in the deeper meaning of it all. Ingenious as the light gun is, magicians have been boggling minds for years with similar cause/effect reversals. Take the "directed choice." You pluck a card at random from a deck, then return it. You alone know the card's identity--let's say it's the ace of spades. The magician then displays four cards so that only you can see the faces. None is the ace. She places the four cards facedown in a square. By sleight of hand, the details of which need not detain us, she replaces one of them with the ace. "Pick two," she says. You do. The magician then discards the other cards (if you picked the ace), or the cards you picked (if not). She points to the two remaining cards and says, "Pick one." If you pick the ace, she discards the other card. If you don't pick the ace, she discards the card you picked. Indicating the one card remaining, the magician says, "Turn it over. Is that your card?" Of course it is. You're amazed and mystified, but as you can see, the trick turns on a simple unsuspected reversal of cause and effect. (Low light, quick fingers, and a couple beers also help.) You thought you were the active agent; in fact you were the patsy. Understand now? Congratulations. You've just passed Marketing 101.

I know I've been wondering about this for about 10 years.

[TexasF355F1]

I've been wonderin' that too. Thats pretty sweet.

[SuPeRcAr_MaN]

I used to think that game was pure magic. This ruined it... But it's cool now that I know...

[jon@af]

Well I'll be damned...

[TheNotoriousMogg]

well damn...you learn something new everyday

[whiteracer]

first game ever played....first learned fact that i can share with others.

[HogieGT-R]

damn.....no wonder why i couldn't kill that damned laughing dog........

[2strokebloke]

Wasn't there another game on the same cartridge? I think it was called "Hogan's Alley" or something like that. We'd always shoot the grandpa, and laugh and laugh.
Man I wish they'd still put two games on the same cartridge/disc (what-have-you?)

[HogieGT-R]

Originally Posted by 2strokebloke

Man I wish they'd still put two games on the same cartridge/disc (what-have-you?)

kind of like the super mario bros./excitebike cartridge...i loved that thing....although i played more excitebike than super mario bros.

[Oz]

I loved those damn things
So high tech

[Alex5390]

i had that on my Sega Master System. It came with the system, you didn't even need to put in a cartrige to play it! There was also some lame motorcycle game. They still have it at the local arcade. Sad.

[Jay!]

I'd always been able to see the white squares around the ducks, but i never picked up on the fact that the rest of the screen blacked out.

Cool article.

[Alex5390]

yeah i thought the white square and black screen was just the flash from the gun. I guess thats what they thought people would assume when making the technology. cool

[Damien]

duh???

[sameintheend01]

mine was super mario/duckhunt in one cartridge.