Secure agreement at an attractive price, then reveal the true cost; commitment already made carries the person through.
Cialdini's 1978 studies with students asked to participate in a 7 a.m. experiment. Told the time only after agreeing, most kept the commitment — and turned up.
In practice
- A gym membership advertised at £15 reveals the joining fee, the minimum term and the peak-hours surcharge after the direct debit is signed.
- A contractor's quote rises once the scaffolding is up, and the householder pays because the scaffolding is up.