Confirmation bias (also known as positive bias) is the tendency to search for, interpret, favor, and recall information in a way that confirms or strengthens one's prior personal beliefs or hypotheses [1].  For example, one might test hypotheses with positive rather than negative examples, thus missing obvious disconfirming tests.

See also: Motivated skepticism, Availability heuristic, Surprise, Narrative fallacy, Privileging the hypothesis, Heuristics and Biases