You know, my girlfriend used to be a member of Mensa. I figure she must have tested pretty high on the ole IQ'o'meter.
Yet her memory is terrible! And her mental arithmetic is far from great. Admittedly, she makes short work of these heavy duty scientific formuli and such like. But still, it seems that even something as apparently consistent as the 'IQ' is in reality, anything but!
Personally, Im of the belief that current IQ testing methods should be scrapped. Im no boffin, but it seems abundantly clear that these tests are ineffective. As you say, on a bad day you'd far lower. Some people have exam anxiety. And for some, the tests simply arent adequate in demonstrating their particular intellectual qualities.
However... when you consider that IQ tests are really just an entrance exam to these societies, the format of testing begins to make a little more sense

Pianistimo,
Id be interested to hear your thoughts on that guy, the Rain Man.
He has an incredibly low IQ. Well, he is mentally deficient! Yet, he is able to remember and retrieve information care beyond the average person... or even the greatest of boffins come to that. I might argue that memory and retrieval are more attributes aside from intelligence. Indeed, the cases of savantism clearly show that memory and intelligence work seperately. That said, I believe that many IQ tests use short term memory as a criteria.
Personally, I think the ability to process AND comprehend is what makes intelligence (in the IQ sense of the word). Being able to process information but then to make sense of it in the real world has to be the important thing. I remember seeing on TV this doc intelligence testing a young child prodigy. He was asking him to describe objects... such as a straw for instance. What was remarkable was that the kid seemed to not only describe the physical appearance of the straw and its function but also HOW it functioned (ie, the physics behind it). You might say that he was simply repeating what he'd been taught, but there seemed little doubt that the kid was making sense of this object on a different level to what a normal child might.
T'was interesting!
SJ