subject-expectancy effect

is when a research subject or patient expects a given result and therefore unconsciously affects the outcome, or reports the expected result.

The subject-expectancy effect, is a form of reactivity that occurs in scientific experiments or medical treatments when a research subject or patient expects a given result and therefore unconsciously affects the outcome, or reports the expected result. Because this effect can significantly bias the results of experiments (especially on human subjects), double-blind methodology is used to eliminate the effect. (wikipedia)

subject expectancy effect, n.Definitions

subject expectancy effect