The anchoring effect is a cognitive bias that describes the common human tendency to rely too heavily on the first piece of information offered. ... During decision making, anchoring occurs when individuals use an initial piece of information to make subsequent judgments.
The anchoring effect is a cognitive bias whereby an individual's decisions are influenced by a particular reference point or 'anchor'. Once the value of the anchor is set, subsequent arguments, estimates, etc. made by an individual may change from what they would have otherwise been without the anchor.