Keywords and the branch budget

Miller's paper is about span: how many items people can hold and repeat back. His number was around seven, and he noticed that people beat it by grouping. A phone number is ten digits and nobody remembers ten things; they remember three groups. He called the groups chunks, and the seven applies to chunks, not to raw items.

Cowan came back to the question with the grouping taken away. When adults cannot rehearse and cannot chunk, the focus of attention holds about four. That is not a correction of Miller. It is the number underneath Miller, the one you get when the trick he described is switched off.

• Four is the ceiling with no structure: a flat list of unrelated things, each one its own item.
• Seven is the ceiling with structure: items grouped into chunks, each chunk holding its members.
• A branch is a chunk. "Supply" holds Guji, Sidamo, the roastery and the first batch. You are not holding four things when you look at that branch; you are holding one, and it unpacks on demand.

So the budget for main branches is four to seven. Under four and the centre is doing the branches' job; the map is a heading with a list under it. Past seven and the branches have stopped being chunks, because you cannot hold the set of them, and the map has become a flat list wearing a circle. Neither number is a law about maps. Both are a description of what a reader can carry, and a map is built for a reader.

The 1956 paper opens with a joke: the author is being persecuted by an integer. Seven keeps showing up in his data and in the world, and he spends the paper wondering whether that is a discovery or a coincidence. His answer, in his own words, is that it is a rough estimate and partly a rhetorical device. He was making a point about chunking, and the number was the hook.

That matters for how you use it. "Seven plus or minus two" is a range from five to nine, offered loosely by someone who was more interested in the mechanism than the digit. Anyone who tells you a map must have exactly seven branches has read the title and not the paper. Anyone who tells you four is the real number has read Cowan and not noticed that Cowan blocked the exact thing a branch does.

A keyword is a retrieval cue. Its job is to bring the sentence back to the person who wrote it, tomorrow, without the notes. Three rules pick the word that does that job, and two tests catch the times the rules were not enough.

• Nouns over verbs. "Guji" brings back the shortage; "short" alone brings back nothing. The thing is the anchor; what happened to it is the qualifier. Keep the noun, add one word of state if you need it.
• The specific over the general. "Sleeve" beats "packaging", "Guji" beats "beans", "roastery" beats "supplier". The general word is the one that could be on any map; the specific one is the one that is only on this map, which is why it brings this meeting back.
• Numbers and dates are twigs, not keywords. "4000 bags" and "1 Oct" are facts about the first batch. They hang off "First batch"; they do not replace it. A number on a branch has nothing to attach to, and next week's number has nowhere to go.

Then two tests. The twig test: could three more things hang off this word? "Guji short" passes; a new fact about Guji has a home. "Leans on Sidamo" fails; it is already the end of a thought. The read-back test: cover the notes, read the word, say the sentence. If the sentence does not come, you cut to the wrong word. Change the word. Do not change the rule.

Three families of word pass the letter of the rule and fail its purpose. They are all short. None of them brings anything back.

• The general noun. "Issue", "update", "discussion", "next steps", "concerns". Each is one word and each could label any branch of any meeting ever held. Read "issue" on Thursday and you will remember that there was one. Daybreak's map had "Legal sign-off" and "origin claim" where a general-noun map would have had "issue" and "risk".
• The verb alone. "Review", "confirm", "send", "model". A verb without its object is an instruction with the important half missing. "Model" brings back nothing; "Price model" brings back finance's request and who has to do it.
• The abbreviation you will not remember. "LP" for landing page reads fine on the night and reads as "long play" a fortnight later. Abbreviate only what you already abbreviate in speech. "FAQ" is safe because nobody says the long form; "WB" for win-back is a puzzle you set for yourself.

Run the questions in this order, because each one is cheaper than the next and most ninth branches fall at the first.

• Merge. Two branches are the same theme with different names. Daybreak's first draft had "Photos" and "Video" as branches; both are assets for the launch email and both went under Comms as twigs. The test is whether one keyword covers both without lying.
• Promote. One branch is what the whole map is actually about, and the others are aspects of it. If "Launch" is a branch of "Autumn planning", you drew the wrong centre. Redraw with the big branch in the middle; the old centre often disappears.
• Demote. The branch is a detail of another branch that got promoted by the heat of the meeting. "Legal" felt like its own theme at Daybreak because the lawyer spoke for five minutes; on the page it is one twig, "Legal sign-off", under Packaging.
• Split. It is a real theme and it does not belong here. Ownership at Daybreak (who owns the checklist, when the date is fixed) is a second subject with its own meeting coming. It gets its own page, and the launch map keeps a one-word pointer to it.

The move that is not on the list is the "Misc" branch: the place where the ideas go that did not fit. It reads as a fifth option and it is not one. It adds a branch, so the count goes the wrong way, and every idea under it has been filed under "I did not decide", which is the one place nobody will look for it.