The Ames Window Illusion, by Adelbert Ames, Jr.

The "Ames window", otherwise known as the "Ames trapezoid", invented by scientist Adelbert Ames, Jr. (copied from here: http://www.youtube.com/watch?v=tc_LqIaO2b8 so that I could comment on it) More about Adelbert Ames: http://en.wikipedia.org/wiki/Adelbert_Ames%2C_Jr%2E This is one of the lesser-known optical illusions, and also involves no "motion inertia" (try viewing it frame-by-frame), or fullscreen or anything. You simply interpret "reality" wrong because your brain has already made up it's own mind about the *shape* of the window. It gets it wrong due to the assuption that the window is rectangular, when in fact it is trapezoidal. Interestingly *even knowing* that the window is trapezoidal, it is still impossible to determine it's orientation by visual inspection (at least to me anyway!). Problem is, I think, that since you don't know the dimensions of the trapezoid, you can't tell the difference between the two possible realities and the usual scenario is automatically chosen (by the brain) instead of *an* unexpected one. Could a computer program be written to come out with the right answer? I'm guessing "no", because again, all of the information has not been provided. I could be wrong of course! perhaps there is a subtle difference that would pinpoint the window's shape... -------- Why is this relevant to this channel? Check out TDTUC episode 10 part 2 (of 5): http://www.youtube.com/watch?v=vN_A_NIDjM0 where Mr. Burke shows us how what we see (our perception of the universe) is entirely determined by a structure that we've already imposed on it. Or see this article which goes into very much detail about just this sort of thing (and why it is a necessary property of cognition in order to amplify the learning process): http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.73.1700&rep=rep1&type=pdf In this case the structure imposed is built-in; the result of some evolutionary process, but the principle is the same for all knowledge. "We see what our knowledge tells us we're seeing" because once a structure is in place, then everything that follows must be viewed in conformance with it. And when our knowledge of the universe changes significantly enough, so does the structure to which everything must fit, and hence *the entire universe* changes. Which is the entire point of the series. - JBW