As I said, imagery based mnemonics. I will admit, however, that the Canadian bodybuilding is a bit of an irrelevance; it just happened to be the case that one of the key scientists involved was a former Canadian bodybuilding champ. He learned about imagery mnemonics from a course he took on public speaking.
Imagery mnemonics were, according to tradition, invented by the ancient Greek poet Simonides after he witnessed the collapse of a banqueting hall he had just been inside. All the banqueters still inside were killed, and Simonides, the only survivor, was called upon to help identify the mangled bodies. He was able to do so by recalling a mental image of where each guest had been sitting when he had been inside reciting his poetry to them. The mnemonic techniques he thereby developed came to be widely used by orators, public speakers, in the ancient world, to remember the points they wanted to talk about, and their proper order, so they could speak apparently spontaneously, without notes without notes. Later, in the middle ages and renaissance, these mnemonic techniques were adapted to religious and mystical purposes.
The experimental results probably could have been published, and certainly should have been, but they weren’t because they were so far from what the researchers had been looking for. They were looking to establish the informational capacity limits of human memory, and one of them, who had been a stage magician performing mnemonic feats as part of his act, suggested that they teach their subjects how to use the mnemonic techniques he had learned for that. When they did so, it appeared that their memories had no practicably measurable capacity limits, and the experimenters gave up. Word got out, however, and a (rather brief and vague) account of the results got published in a book that was more centrally about introducing concepts from computer science and AI into psychological theory. One of the people who read it was our Canadian former bodybuilder, who was thereby emboldened to start doing experiments to explore, and prove the efficacy of, the mnemonic techniques he had learned about over ten years before from his public speaking course.
When you start digging into the details of the history of science, you, more often than not, find a lot of random seeming and contingent influences and connections like this, at least when you are looking at a point where new theoretical directions are taken, or new areas of research opened up. That was very much the case in experimental psychology in the 1960s. (The psychedelic drugs probably had a lot to do with it too. No joke.) Up 'til then, scientific psychology had, for decades, almost all been about stuff like rats running through mazes.
