The answer seems to be two-fold. They provide those with a nagging suspicion that they are latent Leonardos with an opportunity to find out. And they provide a forum for the exchange of ideas.
First things first, then. How can Mensa help you to calibrate your IQ? (Intelligence Quotient, though if you have to ask, you probably can't afford it.)
The first stage in joining the exclusive club is either to phone in, or look out for the little puzzles with which Mensa enlivens the pages of the nation's press. These generally feature a row of bananas, an apple or two and a couple of cherries, but they are no fruit machines. On the contrary, they are expertly devised visual conundrums designed to indicate whether it's worth advancing to the next stage - the home test.
Just pounds 9.95 will secure you one of those, in a plain brown envelope. Breeze through that and you may wish to take the supervised test - another pounds 9.95, but at least you'll have proof. Furthermore, if your IQ registers at more than 148, putting you in the top two per cent of the population, you will be offered membership (pounds 30 a year).
The tests comprise three parts. Language abilities are tested with anagrams, synonyms and the like. Bookworms may waltz through this part but blunt their noses on the numerical questions which follow. Finally, the spacial- orientation round requires you to revolve shapes in your mind without the aid of virtual reality goggles, to unfold dice and to generally play havoc with a stiff neck. Only a successful combination of scores from these three parts will signify a potential Mensan.
Mensa will not divulge how many take these tests every year, but about 5,000 pass and become members (which is just as well, because almost as many leave).
What do you get for your pounds 30? A little gold card that proves you're a member and a monthly Mensa Magazine. This covers a wide range of topics and opinions which, they stress, are not necessarily those of the editorial board of Mensa itself.
Those hoping for a few crackpot theories from the brain boxes (their chairman is Clive Sinclair, after all, above right) might be a little disappointed. The articles tend more to the mundane (the February issue featured "Fit to Bust - Bronagh Miskelly meets fitness instructor Martica Heaner" and "Cousin Jack - John Hosken celebrates the world-wide phenomenon that is Cornwall").
Even so, there is some lively debate on the letters page. One man compared finding "compelling evidence of the existence of God" with "the laws governing differential equations". If this is the sort of thing you argue about over a pint of an evening, then Mensa may well be for you.
There is little evidence, meanwhile, that being a member of Mensa will get you a better job, except in so far as confirmation of your exceptional intellect may give you a certain swagger in the interview stage.
But it may have other pecuniary advantages - among the various small ads in the back of the magazine, listing various Mensa-oriented social occasions, there are many such as this - "Quiz teams put together for raids on pots. Phone Mike". It's one way to claw back the pounds 49.90 it's taken to get there.
Of course, some Mensans get together for more than just pub quizzes. The "fifth Mensan wedding in 12 months" was announced in September's magazine. Whether they will have super-children remains to be seen. Three American members who decided to donate their super-sperm last year attracted a certain amount of negative publicity but there is no real evidence to suggest that high IQs can be passed on.
If they or anyone else does have an exceptionally bright child, however, a sub-division called Mensa for Gifted Children exists to help and counsel on matters of education.
And in case you're wondering, yes, I did take the test. And yes, I am wasted. But don't blame me - blame the home-grown.
Mensa, Mensa House, St John's Square, Wolverhampton, WV2 4AH (1902 772771)Reuse content