Hacker News Reader

Comment by YeGoblynQueenne | Hacker News Reader

The problem with optical illusions like that is that they are, in their vast majority, made of abstract shapes. Most of them play with our perception of distance and depth - and the majority again work on two dimensions, only.

It's really hard to imagine an optical illusion that makes you mistake objects in the physical world for something else- say, panda for a lawn mower or a car for a pigeon, or something like that.

Note that I don't agree that this tells us anything about whether the human brain (or mind) is "like" a machine learning algorithm. To me this question has about as much meaning as asking if the brain is "like" quicksort.

The physical substrates are so clearly different that the only comparison you can make is on the level of capabilities (say, both are Turing-equivalent etc) not that of actual structures. Like, where's the 1's and 0's in the brain?

View on HN

> It's really hard to imagine an optical illusion that makes you mistake objects in the physical world for something else- say, panda for a lawn mower or a car for a pigeon, or something like that.

Here's a physical object that makes you mistake an insect for a plant:

https://en.wikipedia.org/wiki/Phasmatodea

Problem is, mimicry involves copying essential properties of the target object: color, texture, shape, movement dynamics and so on. It relies on true ambiguity. Adversarial examples against neural networks (the interesting ones, anyway) involve a combination of insignificant, seemingly random permutations that only work in their totality. That's a very important difference.

> essential properties of the target object

They are only "essential" properties according to the limitations of your particular perceptual system. To a bee that can see UV light, a stick bug may look entirely different from an actual stick. An animal that hunts by scent would find them clearly distinct.

There is no such thing as "true" ambiguity unless the two objects are actually the same thing in all respects. If they are distinct but appear the same, it's because they are overlapping in some respects but not all.

> They are only "essential" properties according to the limitations of your particular perceptual system. To a bee that can see UV light, a stick bug may look entirely different from an actual stick. An animal that hunts by scent would find them clearly distinct.

This is a very confused statement. Fist, since we are talking about image recognition we are - by definition - talking about vision in the spectrum that can be captured by a digital camera and encoded in a typical image format. Second, there definitely is such a thing as essential property. It is a matter of correlation with reality, as well as internal consistency. For example, plants are green and have leaves because of the way they use sunlight. So permuting color of all leaves in the picture is fundamentally different from permuting luminosity of some random pixels.

What romaniv said- it's a different thing.

A more accurate example in the non-2D realm: https://en.wikipedia.org/wiki/Pareidolia

> It's really hard to imagine an optical illusion that makes you mistake objects in the physical world for something else- say, panda for a lawn mower or a car for a pigeon, or something like that.

Sure but people do, for example, mistake each others' faces or voices. You don't need to mistake your friend for a lawnmower for it to be dangerous.

Also, for example, I often mishear my own name when someone else is speaking. Might not happen with every name but it does with some.

Well, people misidentify others when viewing conditions are poor or when they dont' know the other person well. For instance, say my mother was standing in front of me in broad daylight and I was given half a second to look at her face; I really don't see how I'd fail to identify here, unless her face had changed drastically for some reason.

So, to be fair, this too is a different thing than what we're talking about.

https://m.youtube.com/watch?v=A4QcyW-qTUg

Again, this is an optical illusion that fools depth perception. It doesn't make you see the T-Rex as a tea-pot, say.

Different things.

Fair point; it's not exactly the same mistake. If humans made those, this discussion would probably never happen.

What I tried to rebut is your first, weaker assertion:

> The problem with optical illusions like that is that they are, in their vast majority, made of abstract shapes. Most of them play with our perception of distance and depth - and the majority again work on two dimensions, only.

This makes me see a moving 3d object when I am in fact looking at a static flat object; and I can't shake it, even if I try.

OK, but I did say "the (vast) majority".

Also, from what I can tell, this just happens to work better with a meaningful shape (the image of a T-Rex). It has something to do with how we confuse convex with concave shapes and the T-Rex's snout just happens to be very convenient to demonstrate this confusion (e.g., I think an image of a horse would work as well). I think the illusion would also work with an abstract shape- except it would be harder to find a good abstract shape to demonstrate it as clearly as with the T-Rex.

Reply on news.ycombinator.com