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Comment by bonoboTP | Hacker News Reader

Do you find the following exercises difficult? http://www.geom.uiuc.edu/docs/education/institute91/handouts...

Hm, not at the speed of reading. Takes a bit of slowing down to get some.

A complication is that a lot of these are from elementary school geometry books, so i tend to just remember the answer before getting a chance to look at it.

Can you imagine each Tetris shape, one after the other, in some kind of spatial way? Can you "make" the L shaped one sit on its short side then lie down on the long side?

Sure. And it makes a clang as it falls.

Can't quite play tetris, however - i start to lose track of the pieces once there are like 5-10 of them.

I can think about L shaped one standing upright or lying down on the long side. I don't see them though.

Can you do this? "You see the silhouette of a cube, viewed from the corner. What does it look like?"

Or mark the edges of a cube into thirds, and cut off each of its corners back to the marks. What does the result look like? Can you mentally rotate this shape around?

I don't really see anything. If I attempt to visualize a cube from the corner, I can maybe say I can see the corner and three edges leading from it (to be honest, it's hard to say that I truly see it, but maybe a vague outline of three lines). I don't see the remainder of the cube.

If I try to imagine a cube, and then mark the edges into thirds, I cannot imagine what remains when I cut off corners back to the mark. And the cube itself is more of an idea of a cube rather than visual representation.

I cannot mentally rotate the shape as I do not see a shape.

I'm sure it's hard to believe, but trust me, it's hard for me to believe people can visualize in the way people describe.

Yes I do. Since I can't visualize a triangle in my head, it's hard to visualize what is left over when I cut off at thirds.

The link states that this can be trained. Is that your experience as well?

Do you see any sort of visual imagery when dozing off to sleep? Have you ever played a lot of some visually repetitive game, like Minesweeper, Tetris, Bejeweled etc? I find that if I play a lot of those (hours) then at night when I shut my eyes I can't get rid of visualizations of these shapes in my mind, it's even kind of annoying.

For reference, this is what happens to me. If I spend a few hours playing a particular videogame, its imagery "burns into" my mind - when I close my eyes, I can see recurring patterns from the game (like ground textures or UI elements); if I'm tired, that's an easy way to get me to high level 3 on the "starn scale". The effect disappears after I sleep for a few hours.

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