For example, in problem-solving tasks, people are often sensitive to crucial clues of which they are quite unaware, and they often provide patently confabulated accounts of the problem-solving methods they actually employ.
But six years after its launch, it closed in a torrent of political infighting and mounting financial losses, the clues of which are still found today in the Hall-Carpenter Archives at the London School of Economics.
"We are all very much fascinated by fingerprints, which carve a natural identity for each of us, yet nobody had even the slightest clue of which protein causes this," he said.
He is a meticulous gatherer of clues, some of which involve knowledge of chess, mathematical theories, 19th-century drama, and esoteric writings on criminology.
Soon he was showing me how to solve its obscure clues, many of which consisted of puns.
From Fortieth Street to Sixtieth Street and from the East River to the Hudson, fifteen teams are scrambling across Manhattan in search of clues, each of which points to another location.
Here he is in a solution published last week: 24a How some answers may be found in clues, some of which I'd denoted (6) Some of "which I'd denoted" is, quite literally, HIDDEN.
He now had three clues, one of which -- because of the image of the frozen lone rescue worker that was now embedded in his mind -- filled him with dread: "If I was hit from the front," he said, "then I was most likely facing the building, like that guy, as it came down".
But no mechanical dog can replace what even Hasbro admits is the lasting and somewhat surprising popularity of such classic games as Monopoly, Candy Land and Clue, all of which were born before many of today's young parents.
Every so often, Guardian solvers would open the Saturday paper to find no numbers in the grid and know they were in for a different kind of challenge: one of Araucaria's "alphabetical jigsaws": a list of clues for which the answers begin with A, B, C and so on, which must be fitted into the grid "jigsaw-wise, wherever they will go".
Out of 32,000-plus clues overall, most of which could have gone wrong in multiple ways, this is not such a bad record -- if I do say so myself.
