In the evening you visit Rani.
Maybe you'll be able to find out what the device is for for real.
Hopefully she's not mad at you anymore.

You also have some snacks with you.
Sali is already gone, so you're alone with Rani again.

Hey, you're finally here.

Yeah, did you find something out already?

No, I just tried it a few times and everything was the same as before.

And what about the idea you had?

Oh, I thought it might be a stress detector.
I'm always stressed, but you're always pretty relaxed. Sali is also pretty relaxed normally, but you stressed her.
Who else did you let use the device?

Only Pipo and the neighbor girl.

Yeah, Pipo is pretty relaxed, too. What about the neighbor girl?

She didn't seem stressed.

Hmm...

Let's get some snacks first and relax.

Good idea. Let's continue our work later. And then I'll try it again.

You put out your snacks and relax on the couch while watching a movie.

After some time, Rani grabs the device again and tries it a few times.

Still the same. I probably have to relax more.

You also try it. You don't put much attention it.

Still the same, I press left and the left light is turned on.

You keep watching the movie.

But that's not the same. That's what normally happens when I use it.

Oh, but I don't feel stressed now.

You didn't seem to pay a lot attention to the device this time. So maybe if you put a lot attention to it, it will work differently.

That would be weird.

Rani turns off the TV again and you give it another try.

Oh, you're right. Now it's the same as before.

Rani snatches it from your hand.

Hey!

She already tried it.

It's still the same for me, though.

That's weird.

Maybe you were distracted by the TV?

I'm not sure.

Maybe try to tell me what you think while doing it.

Rani gives it back to you.

Hmm... I turn the device on. Oh, the right light blinks. I'll just press the right button. And now the left light glows now.

Did you press the right button because the right light was glowing?

Yeah, but it also happens when I press the other button.
I'll try it again.
I turn it off and on again. Now the right light glows again, so I'm pressing the left button this time. And the right light glows.
It's always the opposite.

Hey, I think we got it! The short glows are not a technical defect. They are, what the device is about.

How so?

Close your eyes while turning the device on.

You do as she said.

Now open your eyes and press a button.

You press the right button, and the right light glows this time.

You always decide to press the button below the light that glows. Or you explicitly decide to press the button below the light that doesn't glow.
Your decision always relies on the light that glows at the beginning. Because I thought, it's a technical defect, I just pressed the left or the right button without paying attention to the lights.

Okay, but why? And how is this useful?

I have no idea...
But let's find it out!
You'll stay the whole night anyway, won't you?

Yeah!

So the result basically relies on what we thought before pressing the button, right?

I think so.

Let me try it, too.

You give it back to Rani.

Now I'll press the button below the glowing light.

Rani turns it on, the right light glows, so Rani presses the right button, and then the left light glows.

And next I'll press the button below the other light.

Rani turns the device on, the left light glows, so she presses the right button again, and the left light glows.

Yeah, it's simple. No matter what, if I make my decision depend on the light, the other light glows.

Yeah, I get that.

Let's try something. If the left light glows, I'll flip a coin to decide which button to press, if the right light glows, I'll just press the right button.

What do you think this will show us?

I'm not sure. It might lead somewhere.

You take the device and turn it on.

It's right!

Then just press right.

You press right but this time no light is turned on.

That's weird. Nothing happened.

Did you press hard enough?

You press the button repeatedly, and after a while, the right light is turned on.

Hmm... That was weird. Let's do it again.

You turn it on and the right light glows again. You press the button and no light gets turned on.

Wait, don't press anything else!

You didn't press anything else yet and just wait. After some seconds, the left light turns on.

I think, I have an idea, how it works. Let me try something.

She takes the device again.

I'll always press the left button, but if the left light glows, I'll do it immediately, if the right light glows, I wait some seconds.

You watch her. The left light glows, so she presses immediately. But it takes a few seconds until the light starts glowing.

The next time, the right light starts to glow first. So she waits a bit before she presses it. But the left light starts to glow immediately after the right one turns off.

Do you understand?

Rani seems very excited now.

No...?

In gerenal the device is pretty simple. I press the left button, the left light is turned on. I press the right button, the right light is turned on.
But only if I pay attention to the lights, something else happens. The device reacts not to what I do, but to what I would have done if the other light was turned on.
Only if I don't pay attention to the lights or decide to do the same no matter which light glows, both results would be the same and it behaves in the simple way.
And how it works? No idea!

And what can we do with it?

I already got an idea for that. It might boost my productivity by a lot. But let's go to bed for now. I'm getting tired.

Yeah, so I'll sleep in your bed?

If you don't mind.

Nice!

You follow her to her bedroom and get ready to sleep.
While you enter the bed, you get concerns.

I didn't allow you to keep the device for yourself. You can keep it for now, but you have to give it back to me when I find a use case!

No problem.

You are tired and fall asleep quickly.