Guide

The recurring fight between these two types comes from a disagreement about what counts as evidence, not from either one being difficult.

Why a planner and an improviser have the same three arguments on every trip, and the anchoring arrangement that works better than compromising.

What is really being asked for when someone leaves a good evening and closes a door, and the one clause that stops it being read as anger.

Matched pairs start months ahead and pay for it later, because the gaps line up and agreement stops being evidence of anything.

Roles in a group are claimed rather than assigned, in order of who is least able to sit through the silence where that job should be.

What a pause, a description and a small mishap reveal in the first half hour, and why guessing somebody's four letters from one evening is a bad party trick.

Answering a message is one motion for some people and four for others, which is most of what separates a two-second reply from a three-day one.

Sustained pressure does not exaggerate a type, it inverts it, which is why the change alarms everyone around the person and confuses the person themselves.

One friend labels four boxes, the other fills nine. Where each order wins, and why they swap positions the moment the unpacking starts.

Four different things produce the same silence, and the format itself decides which of them the meeting is able to collect.

Why the shy extravert and the sociable introvert are both ordinary, and what the letter is actually measuring.

The middle letter decides which kind of information arrives first, which is why one person describes the coffee and the other describes the Sunday.

Both letters are procedures for choosing, and they differ in what they hold constant: the rule, or the effect on the specific people involved.

The last letter measures when closing a question feels like relief and when it feels like a loss, which a deadline demonstrates better than a tidy desk does.

A son-in-law who did not fit the family, a book by Jung, a wartime problem about matching people to work, and the route from a filing cabinet to a testing company.

The four letters function as social shorthand in Korea in a way they never did in the country the questionnaire came from.

A shorthand spreads where it answers a question people are already asking and has no incumbent in the way, which is why one country got slang and the other got practitioners.

The workshop converts an unspeakable conversation about a colleague into a speakable one, and quietly changes the answers while it does it.

The recognition you feel reading your result is partly the description and partly a trick any description can play. How to tell which is which.

A dichotomy reported from a running total is unstable near the middle, which makes a changed letter an accurate measurement rather than a broken one.

A plain account of what the sixty questions ask, how they add up to four letters, and which part of the result is the least solid.