This book is doing three things and I'm not sure it manages two of them though the third one is enough to make it worth the read.
Breakthrough thinking - I give the Author full credit for putting his arguments across, fighting them, and then bringing in whole studies that discredit what he's arguing and doing it full service. While he clearly has a different argument, he gives full credit to the other studies. I don't know if I've seen this done so professionally - without a hint of shade being thrown. By the same token, his argument that XYZ items he goes through in his book are all leading to the snap loses a lot of it's impetus along the way.
I think we all have had, many times, and have seen, that moment of crystal clear understanding. Humor is very much based on that cognitive snap. But as he says, no one woke up one day and discovered a world shattering idea. It comes from long work, dedication, and focus on a problem. So you get what he's talking about, but the reality of the sudden leap is that it's all based on who you are and what you do, not some bolt out of the blue.
Second thing is insight puzzles. Again, full credit, has he dips his hat to my issues with puzzles like this in general. The reason so many memory games don't really work in the practical world is because they just make you better at that memory game. And, likewise, the reason you don't need to do insight puzzles to make yourself a better thinking is because those puzzles don't provide very much practical application. Don't get me wrong, I enjoyed wrapping my brain around them all, might even look further into it, but as tools, they're useless.
As uses to figuring out breakthrough thinking? Indeterminate. Even the couple puzzles based on a real world event were synthetic. It's not like you could go to that place and get the Terroir of it and come up with a good answer. And all the questions were, in general a) out of the blue b)bereft of data and c) often needed additional explaining. Point is, as interesting as they were, the studies that came out of testing the puzzles where much like the puzzles themselves, interesting but not ultimately practical.
So, down to the third thing, which I IMMEDIATELY began using. (I'm in marketing and I'm kind of a nature enthusiast kind of guy, you'll see why I bit this pretty hard) Perkins takes the aspects of problem solving/crafting new ideas (abstracts phenomena) and realigns it to a topographic landscape to be investigated, survived, gotten lost in, and ultimately works by finding your way out. He gave real activities, set in this landscape, for how to expand idea, gather more information on an idea, re frame the problem or idea, and decenter.
It's an interrelated process in an attempt not only to home in on the idea or solution - but how to get around idea's that seem almost right or almost good enough but are not really what you're looking for. Making the abstract concrete lets you play with it, think about it in new ways.
I'm not going to do an explanation justice. However, I might just keep this one with me, either as a reminder or for a while until I can habitualize the process. I think the book was geared towards the 'art of scientific discovery' but I see nothing in here not useful to marketing, maybe even more so. I kind of question people who write and market books about marketing... stinks of the meme, "How to write a book make a million dollars" book.
Four starring this because, while I think it actually changed me for the better, the author shot himself in the foot a few times (ow!) and in trying to pull in proof of his idea, mostly showed how tenuous a thread he was tugging on.