> I think this is a great example that shows how our brains remember/recognize things.
It may also have much to do with 'who' was asked. As an Engineer, I immediately noticed the missing frame member on the first rendering image at the very top of the web page. But, most people one would meet 'on the street' are not Engineers, and they very likely do not even look at a bike with a 'how does this work' eye. And if one does not even try to 'analyze' the bike mechanism, even a little, one surely will never remember the constituent parts.
It may also have much to do with 'who' was asked. As an Engineer, I immediately noticed the missing frame member on the first rendering image at the very top of the web page. But, most people one would meet 'on the street' are not Engineers, and they very likely do not even look at a bike with a 'how does this work' eye. And if one does not even try to 'analyze' the bike mechanism, even a little, one surely will never remember the constituent parts.