Greenlight

Built to put science to the test


Confused?

Don't know what to do?

Keep pressing the button 20-30 times until something weird happens. Then read on.

What is going on? (Spoilers)

Eventually, it might look as if the light is flashing ever so slightly before you press the button! But of course, that can't actually happen. Without a superintelligent computer and algorithms beyond what machines are currently capable of, it would be nearly impossible to actually predict your choices with only this information. But this might have.

So how?

In essense, it's because your brain automatically and retroactively adjusts time.

In the first 20-30 presses of the button, the light is actually delayed slightly. Because of the repetition, your brain starts to eliminate that extra time.

Here's an analogy (that uses the same phenomenon I think). Sound travels slower than light. So we get used to many years that we will hear the sound after we see the light. Just simply think of the last time you heard thunder or saw a fireworks show. Because of the constant repetition, our brains connect the two ideas. And at distances of a couple hundred meters, the difference is so small (less than half a second) that our brain associates them as happening at the same time. We hear them differently, and our brain adjusts our memories so we remember them at the same time.

This is pretty much what's going on here.

For the first 20-30 button presses, the light is delayed by 100 milliseconds. This is a significant delay for our brain to precieve it (1 millisecond would not work). But it is also small enough that our brain thinks of them as connected.

So after many trials, we get used to the delay and start to not precieve it. We get used to us remembering the light 100 milleseconds before it happened. So when the delay is removed, we still think of the light happening 100 milliseconds before it actually happened. That just happens to be 100 milliseconds before we press the button!

It's because our brains haven't adjusted.

Why would I make such a useless thing?

Simply put, I wanted to test some science. I've heard about a study that did this experiment and found these results, and wanted to know what it actually felt like to be a guinea pig. Hence I made this.

You can also read an interesting article from the Scientific American on this subject.

For completeness, here's the citation to the original journal article in case the link two paragraphs above ever breaks:

Stetson, et al. “Motor-Sensory Recalibration Leads to an Illusory Reversal of Action and Sensation.” Neuron, vol. 51, no. 5, 2006, pp. 651–659.