Definition: Anchoring Bias is the human tendency to overly trust information, especially the first piece of information that is available (treated as an "anchor), in decision making and negotiating.
Once an anchor is set, subsequent judgments are made by adjusting, reasoning away from that anchor. Also there is a tendency to interpret subsequent, additional following information around the anchor.
The "anchoring and adjustment" heuristic was pioneered by Kahneman and Tversky.
AB is also called Focalism and is a form of cognitive bias similar to confirmation bias and status quo bias.