Ask for almost nothing first.
Freedman and Fraser's lawn-sign study is chapter 3. A three-inch window sticker, accepted by nearly everyone, more than tripled subsequent agreement to a billboard that would obscure the house.
The mechanism is not gratitude and not momentum. It is identity. Bem's self-perception theory holds that people infer their own attitudes from their own behavior, in much the way an observer would, and a person who has just displayed a civic sign has evidence about themselves. The second request is then evaluated against a self-concept that was edited by the first, rather than against its actual cost.
The conditions that make it work are specific and they are the operational content of this law.
The first request must fall below the refusal threshold — small enough that declining would be churlish. It must be effortful enough to be noticed; a request that costs literally nothing produces no behavioral evidence. It must be public rather than private, since observed behavior is stronger evidence about the self. And above all it must appear freely chosen, because a target who can attribute their compliance to pressure has an external explanation and does not need to revise anything.
That last condition is what separates this from coercion, and it is why the technique is applied with a light hand. Pay someone to display the sign and the effect disappears.
Schein's account of the Korean POW camps, chapter 4, is the state-scale version, and it is the reason this law sits third rather than lower. Chinese interrogators asked only for statements no reasonable person would refuse — that the United States is not perfect, that unemployment exists — in writing, signed. Then a list. Then an essay, in a competition with a small prize. Each step was continuous with the last, and the prisoner had authored the ladder himself.
The boundary is informed consent. A single small request is not manipulation. A designed sequence in which each step exists to make the next available is a way of obtaining agreement to something the person would have refused if asked directly — which is a description of what consent is supposed to prevent. Recruitment into coercive groups, into MLM structures, and into financial fraud all run on this, and it is why the escalation is the thing to audit rather than the item.
The counter is chapter 308.
Countered by The Small Yes That Owns You