The rat study
The observer-expectancy effect (also called the experimenter-expectancy effect, observer
effect, or experimenter effect) is a cognitive bias found in science that
occurs when a researcher expects a given result and therefore unconsciously manipulates an
experiment in order to find it.
Because the observer-expectancy effect can skew the results of experiments (especially on
human subjects), double-blind methodology is used in attempts to eliminate the effect.
An example of the observer-expectancy effect is demonstrated in music backtracking, in which
hidden verbal messages are said to be audible when a recording is played backwards. Some
people expect to hear hidden messages when reversing songs, and therefore hear the messages,
but to others it sounds like nothing more than random sounds. Often when a song is played
backwards, a listener will fail to notice the "hidden" lyrics until they are explicitly
pointed out, after which they are obvious. Other prominent examples include facilitated
communication, dowsing, and applied kinesiology.
Clever Hans - a horse who seemed to be performing arithmetic and other amazing skills, but
in reality took cues transmitted unconsciously by his trainer and observers.
Placebo - an inert medicine or preparation which works because the patients thinks it will
N-rays - imaginary radiation
Pygmalion effect - teachers who expect higher achievement from some children, actually get it
Reflexivity (social theory)
So on & so forth.
Asish