Source: Tversky and Kahneman's research on the anchoring heuristic; applied to first offers by Adam Galinsky and Thomas Mussweiler
The first number mentioned tends to pull the final outcome towards it. Making a well-researched first offer can shape the whole negotiation in your favour.
When to use it
Use it when you have good market information and can make the first credible offer.
How to apply it
Research market rates for the role, level and location.
Set an ambitious but defensible opening figure above your target.
Prepare a short justification based on market data and your track record.
State your number confidently and then stop talking.
If they anchor first with a low figure, reset clearly with your own evidence-based number.
Tip: An anchor so extreme that it seems unreasonable can damage credibility; keep it defensible.