1/ Interesting possible rationale for how progressive summarization mimics the way the brain works, from How Emotions Are Made by @LFeldmanBarrett
2/ To be more efficient, a streaming video will send only the differences from one frame to the next. This reduces the redundancy of sending nearly the same data again for each frame 
3/ Our brains process sensory info in much the same way. Instead of receiving and interpreting all the data for a visual scene that barely changes from one moment to the next, it only processes *changes* in the visual scene for efficiency sake
4/ The concepts that are formed from these sensory inputs are stored in “conceptual hierarchies” where increasingly abstract concepts store info more efficiently by “inheriting” the concepts below them. I.e. you see millions of pixels, lines, and shapes as a “book”
5/ In this example, we get a “progressively more efficient summary” of what we are seeing as we go from pixel to line to shape to book. But you NEED the step by step progression from concrete to abstract concepts, because a book means nothing without lines and shapes
6/ Progressive summarization makes the process of creating these conceptual and perceptual hierarchies explicit, increasing efficiency by reducing redundancy. Think about it: what other summarization method has you create no new information, such as a separate table or index?
7/ By leaving the key point in context, it can be read with maximum efficiency, because it “inherits” clues from the surrounding context. Each layer of summarization is like a separate frame in a streaming video, not duplicating any information from the layers before and after
8/ Thus “absorbing” a prog. summarized note is like watching a little movie, except instead of building bottom up, from most concrete to most abstract idea, like practically all articles/paragraphs, you start at the most abstract idea and work your way down
9/ This involves starting at the key points, and expanding outward into surrounding text. Tremendously efficient because you can immediately move on from a note that doesn’t match what you’re looking for. And for familiar ideas, the most abstract point is often enough
10/ So what prog. summarization is actually doing is reordering the contents of pieces of writing into explicit conceptual hierarchies of ideas, with the most compressed/condensed/abstract version of the idea at the top where it’s most noticeable
11/ By hiding most of the details and focusing on only abstract ideas, you can review more ideas more quickly, hold more in your head at the same time, see farther flung connections, and postpone most of the detailed work for later
12/ It’s like clicking disclosure arrow on a folder to hide its contents, so you can move it around your brainspace effortlessly. But finding the right “title” for that folder has to be done in stages, because it only means anything in the context of the “frames” leading up to it
