In what became 5th most-read new post on LessWrong in 2012, Morendil told us about a study widely cited in its field... except that source cited, which isn't online and is really difficult to get, makes a different claim — and turns out to not even be the original research, but a PowerPoint presentation given ten years after the original study was published!
Fortunately, the original study turns out to be freely available online, for all to read; Morendil's post has a link. The post also tells us the author and the year of publication. But that's all: Morendil didn't provide a list of references; he showed how the presentation is usually cited, but didn't give a full citation for the original study.
The link is broken now. The Wayback machine doesn't have a copy. The address doesn't give hints about the study's title. I haven't been able to find anything on Google Scholar with author, year, and likely keywords.
I rest my case.
WRT the shannon example... well, yes and no.
I suppose something similar is going on: Shannon has been invited to step out of the frame that he's in and step into a new one, where he is identifying with his brother, who knows something important about how to get to a solution to the puzzle from where Shannon is now, and that reframing helps encourage creativity. But also, and significantly, Shannon's brother has given him a new datum: there is a discrete thing-to-be-told which would significantly help. (This is, admittedly, implicit. But if I don't assume it, the story makes no sense to me.)
So no, I don't think it's the only thing going on, or necessarily the most important thing.
And I disagree with "you can always give it to yourself," actually. Or, rather, with the implicit statement that doing so is necessarily useful. For some puzzles his brother might have instead said "Huh. You probably want to rethink your whole approach." Which is also a hint I can always give myself, but it's a different hint that leads me in different directions.
There's probably a huge number of hints like that I can give myself for any given problem, but picking them at random is perhaps not the best problem solving strategy.
Still, if I'm stuck, trying a few is better than nothing.
WRT the Benja search... I suspect that was more of a case of trying harder by virtue of being motivated by the knowledge that success is possible/likely, and to some extent breaking out of transient mental sets.
But even if it were a case of temporarily reconfiguring more persistent unhelpful filters like I describe, it wouldn't follow that Benja has a "gwern filter", merely that Benja, like gwern, has some learned techniques for finding stuff on Google, which includes 'search for direct quotes' along with a million other things, and that the default Benja filter for whatever reason excludes that technique when it searches for techniques to suggest for this kind of problem, and the role-playing exercise encourages disabling the default Benja filter, making that technique easier to access. The "gwernyness" of that reconfiguration, much like the "markiness" in my example, is rather tangential; the importance of being gwern, in this hypothetical, would be that it entails not being Benja.
But he's solving a puzzle, there's always a thing-to-be-told!