# 49. Manipulation of bias and heuristics in decision making ## 49.5. Methodology/Refinements/Sub-species ### 49.5.23. Experimenter's or expectation bias This is a predisposition for experimenters to believe, certify, and publish data that agree with their expectations for the outcome of an experiment, whilst disbelieving, discarding, or downgrading the corresponding weight of data that appear to conflict with those expectations. A manipulator may trap an experimenter into defending an indefensible result, simply because the experimenter feels responsible for the data and the result. Alternatively, a manipulator may co-opt a willing experimenter into conspiring to alter results and data to confirm a pre-defined expectation.