> I too seem to recall being taught that our eyes see "samples", and our brains fill in the blanks

I too might tend toward this explanation. I know that we only see very clearly in the small central portion of our field of view and fill in the rest beyond the divide of our optical nerve.

Re. Strobes ... I was once told a story about a friendly old gentleman on a train. The man said that in the 20s or 30s he had sat outside a university in Switzerland and watched a queer bloke looking at a water fountain through his hand. Intrigued he asked the man what he was up to. He was told to notice that when one opens and closes one's fingers quickly while peering through them that the foutain seemed to stop moving. Shortly after the man was greeted by the person he was waiting for and left. At the same time a friend walked up and asked 'Did you know who that was?'. He was a bit bewildered to discover he'd been chatting to Albert Einstein :-)

Anyway, thanks for your explanation Faldage, but I'm not sure about the 'error' part - it looks right to me! I'll be interested to hear your friend's comments, Ted.