Bias+Effects

[|Bias Effects]
Hawthorne, Pygmalion and Placebo Effects Robert Rosenthal and Lenore Jacobson (1968/1992) report and discuss the **Pygmalion effect** at length. In their study, they showed that if teachers were led to expect enhanced performance from some children, then the children did indeed show that enhancement. The purpose of the experiment was to support the hypothesis that reality can be influenced by the expectations of others. This influence can be beneficial as well as detrimental depending on which label an individual is assigned. The [|observer-expectancy effect], which involves an experimenter's unconsciously biased expectations, is tested in real life situations. Rosenthal posited that biased expectancies can essentially affect reality and create self-fulfilling prophecies as a result. In this experiment, Rosenthal predicted that, when given the information that certain students had higher [|IQs] than others, elementary school teachers may unconsciously behave in ways that facilitate and encourage the students' success. The prior research that motivated this study was done in 1911 by psychologists regarding the case of, a horse that gained notoriety because it was supposed to be able to read, spell, and solve math problems by using its hoof to answer. Many skeptics suggested that questioners and observers were unintentionally signaling Clever Hans. For instance, whenever Clever Hans was asked a question the observers' demeanor usually elicited a certain behavior from the subject that in turn confirmed their expectations. For example, Clever Hans would be given a math problem to solve, and the audience would get very tense the closer he tapped his foot to the right number, thus giving Hans the clue he needed to tap the correct number of times. Source: Wikipedia (Observer-expectancy Effect is linked to more information on Wikipedia.) Information on Clever Hans can be found at: []
 * experimenter effects** A term used in psychology to highlight the ways an experimenter or researcher may influence the outcome of an experiment through his or her presence.
 * Hawthorne studies** From 1924 the Western Electric Company of Chicago, influenced by scientific management theories, measured the impact of different working conditions (such as levels of lighting, payment systems, and hours of work) on output. The researchers, Fritz Roethlisberger and William J. Dickson, concluded that variations in output were not caused by changing physical conditions or material rewards but partly by the experiments themselves. The special treatment required by experimental participation convinced workers that management had a particular interest in them. This raised morale and led to increased productivity. The term ‘Hawthorne effect’ is now widely used to refer to the behaviour-modifying effects of being the subject of social investigation, regardless of the context of the investigation. This can effect the reliability of an experiment.