Originally posted by Grampy Bobby
Out of my depth, moonbus, though I'm fascinated with the concept; any other examples of Mensa's 'testing for the obvious'?
Pattern recognition of all sorts is a similar case, often seen on IQ tests and equally a slave to obviousness.
For example, a test shows several two-dimensional shapes, the testee is to pick the one which does not fit. E.g., circle, square, triangle, trapezoid, pentagon, etc.
"Fitting" is relative to some criterion of fitness, and the obvious criterion is not necessarily the only possible one. One could be looking at the number of vertices in each figure and make a simple arithmetical series out of it--which reduces to the above-mentioned error (for some possible algorithm, any number of vertices could be the next one in some less-than obvious series). Or, one could be looking at some other feature of the shapes (e.g., their enclosed areas or circumferences) and derive some totally different criterion of fit-doesn't-fit.
Any set of objects--cat, dog, gerbil, cow, tiger, parrot--of which one is supposed not to fit, would be open to the same objection. One might think of "domesticated animal" as the criterion of fitting, so tiger would not fit, but there are indefinitely many possible criteria, such as "mammal" or "quadruped", in which case parrot would not fit, or "non-ruminant" in which case cow would not fit.
Chess is a wonderful way to see what different patterns different people see. Rudolf Spielmann (I think) said that he understood Alekhine's combinations, but not how he got to the positions which made them possible. That shows that Alekhine was seeing patterns no one else saw; one of the marks of true genius.