A ditloid is a type of word puzzle[1] in which a phrase, quotation, date, or fact must be deduced from the numbers and abbreviated letters in the clue.
[1][dubious – discuss] The name 'ditloid' was given by the Daily Express newspaper,[1] originating from the clue "1 = DitLoID", to which the solution is 1 Day in the Life of Ivan Denisovich.
[2]Will Shortz originated the current form of this puzzle and first published it in the May–June 1981 issue of Games magazine, calling it the Equation Analysis Test.
Shortz based the puzzle on the Formula Analysis Test – Revised Form published in Morgan Worthy's 1975 book AHA!
My experience was that people often had the answer to an item come to them when they were not consciously thinking about the puzzles, but relaxed, such as in the shower or about to fall asleep.