Your Brain Can’t Handle the Moon | Hacker News Reader

Your Brain Can’t Handle the Moon

nautil.us

47 pointspmcpinto22 comments

I always thought it was a very simple relative size illusion. When placed next to objects on the horizon that provide a relative measuring stick of size, we perceive the moon as large in comparison. When the moon is high and we instead have a vast and large sky free of landmarks to use as subconscious or conscious measuring sticks, it appears comparatively small.

There is a lot of cognitive function in-between, sure, but I never thought it was so complicated.

But that's complicated enough! Our brains use ad-hoc algorithms even for simple things like relative size. Look at relative brightness - there are endless optical illusions where a patch of dark and a patch of light are actually exactly the same tone.

Context is everything to our brains/vision system. Its alarming how warped our perception is.

It would be alarming if our perception was not warped—contextual awareness is far more useful than absolute perception in non-specialized situations (like most survival tasks).

I agree, that's always been the most likely explanation to me as well. You can see this phenomena with many things...

I was at a concert and saw loudspeakers on the top of some poles. I immediately associated them with shelf speakers, and my brain told me they couldn't be more than a foot tall. Then later I saw a worker climbing the pole to do maintenance and realized each speaker box was taller than he was.

I've also noticed this illusion in the city. There's a particular street that has a hill. As you drive up this hill, the top of a skyscraper is framed by the road and trees nearby, and it looks absolutely massive. Then you crest the hill and see the entire thing (along with the rest of the buildings downtown) and they look so much smaller and distant. It's really striking.

This website seems to republish articles periodically: http://nautil.us/issue/19/illusions/your-brain-cant-handle-t...

The older article was on HN as well: https://news.ycombinator.com/item?id=8635384

That seems kind of skeevy of nautil.us. [EDIT: Although, to their credit, they do say at the veeeeery bottom they originally published it 2014.]

What's skeevy about it?

I'm not sure, I keep flip-flopping on it.

On the one hand, I can see how it'd be useful to new readers to resurface good old content, but it's also irksome to old readers. It's annoying to pick up a new magazine and have read the articles before, or a new book by a favorite author and discover that it's just the first half of an older, larger novel, or a short story collection and find that the stories have all been published before. You've wasted your time, money, and now you have nothing to do on your six hour flight.

I suspect the largest problem is that I've spent too much time around SEO people, so whenever I see anything slightly unexpected with how content is surface, I can just hear them in my head, saying things like, "And then three weeks from now, we'll 403 redirect the old URL to the new URL, doubling our google link-juice."

There's nothing necessarily wrong with republishing old content, it just strikes me as ... skeevy.

I think that republishing is good if the content is worthy, and maybe didn't get the attention it deserved.

Republishing/re-promoting is kind of like spaced repetition software for content. I always take note of old articles on the front page of HN because its a signal they have lasting value.

Addition of originaly appeared on $date in the top credit would be perfect.

What surprised me about the moon was when I read that its diameter is less than the width of Australia. I just imagined it to be bigger than that.

My brain can't handle the kind of pop-ups that article throws in my face.

Adblock+, bro.

I've got adblock, but it doesn't stop that popup for some reason.

Same here. So, I had to use Quick Javascript Switcher to turn off Javascript for this site because running your Javascript on my machine is a privilege, not a right.

For me the illusion isn't really the Moon illusion but the sky illusion. Sky on top of me feels closer to me than the horizon, even though I know it isn't, so it's not that surprising that the same angular size near the horizon feels bigger than on top of me.

After the first couple of paragraphs my own analysis is this:

1. Distance in the mind is based on cues; 3d binocular cues only work at distances less than a mile or so. Beyond that your mind depends on relative reasoning to know 3d structures. A moon close to the ground will connect to the ground you see and be placed at the furthest possible distance. Anything at that distance is made to feel larger in the mind.

2. If you look at a moon up in the sky, there are no cues to indicate how far away it is or anything.

3. A moon up in the sky is surrounded by empty space. Lots of empty space will conceptually "crowd out" the moon and make it appear smaller not larger.

I then finished reading the article. Conclusion of researchers: #1. Good joy guys? ...

You still have depth perception with one eye...you get parallax from head movements. When viewing photos you don't get any parallax.

I wonder if there could be experiments using VR to measure this effect?

People have made head tracking systems by mounting the sensor bar from a Wii on the brim of a baseball cap, and then placing the Wiimote on the top of their screen. I saw a video of someone playing Half Life 2 with it, and it looked to be surprisingly effective. Also, the difference between the Oculus Rift DK1 (which does not have positional head tracking) and the DK2 (which does have it) is pretty incredible. Obviously, the type of virtual environment you're dealing with has a huge effect on how strong the illusion is.

The moon illusion is the most intriguing illusion I know. I'm sure it can be replicated with experiments and such, but the primacy of our nearby neighbor makes it special. When a friend of mine told me about I was convinced it had to do with an atmospheric phenomenon, and that taking pictures would verify this. And then I looked it up... more than puzzling!

Moon is bigger closer to horizon, thanks to refraction.

If that were the case then it'd be bigger in photographs. It isn't.

Well it is a few arc seconds, but it is bigger :-)

Reply on news.ycombinator.com