Editing Observer bias (section)

== Examples ==
Examples of observer bias extend back to the early 1900s. One of the first recorded events of apparent observer bias was seen in 1904, with the case of "Clever Hans". [[Clever Hans]] was a horse whose owner, Wilhem von Olson, claimed could solve arithmetic equations. Von Olson would ask Clever Hans a series of questions involving arithmetic functions, and the horse would appear to answer by tapping its hoof with the numbered answer. This example was investigated by the psychologist [[Oskar Pfungst]], and it was found that when the horse was nearing the correct number of taps, the owner would subconsciously react in a particular way, which signalled to Clever Hans to discontinue his tapping. This only worked, however, when the owner himself knew the answer to the question. This is an example of observer bias, due to the fact that the expectations of von Olson, the horse's owner, were the cause of Clever Hans actions and behaviours, resulting in faulty data.<ref>{{Cite journal |last1=Samhita |first1=Laasya |last2=Gross |first2=Hans J |date=2013-11-09 |title=The 'Clever Hans Phenomenon' revisited |journal=Communicative & Integrative Biology |volume=6 |issue=6 |pages=e27122 |doi=10.4161/cib.27122 |pmc=3921203 |pmid=24563716}}</ref>

One of the most notorious examples of observer bias is seen in the studies and contributions of [[Cyril Burt]], an English psychologist and geneticist who purported the heritability of IQ.<ref>{{Cite journal |last=Gillie |first=Oliver |date=1977 |title=Did Sir Cyril Burt Fake His Research on Heritability of Intelligence? Part I |journal=The Phi Delta Kappan |volume=58 |issue=6 |pages=469–471 |jstor=20298643 |issn=0031-7217}}</ref> Burt believed, and thus demonstrated through his research because of his observer bias, that children from families with lower socioeconomic status were likely to have lower levels of cognitive abilities when compared with that of children from families with higher socioeconomic status. Such research and findings had considerable impacts on the educational system in England throughout the 1960s, where middle- and upper-class children were sent to elite schools while the children from the lower socioeconomic demographic were sent to schools with less desirable traits. Following Burt's death, further research found that the data in Burt's studies was fabricated, which was presumed to be a result of his observer bias and the outcomes he was intending to find through his studies.

Another key example of observer bias is a 1963 study, "Psychology of the Scientist: V. Three Experiments in Experimenter Bias",<ref>{{cite journal |last1=Rosenthal |first1=Robert |last2=Fode |first2=Kermit L. |title=Psychology of the Scientist: V. Three Experiments in Experimenter Bias |journal=Psychological Reports |date=1963 |volume=12 |issue=2 |page=491 |doi=10.2466/pr0.1963.12.2.491}}</ref> published by researchers [[Robert Rosenthal (psychologist)|Robert Rosenthal]] and Kermit L. Fode at the University of North Dakota. In this study, Rosenthal and Fode gave a group of twelve psychology students a total of sixty rats to run in some experiments. The students were told that they either had "maze-bright" rats, who were bred to be exceptionally good at solving mazes, or that they had "maze-dull" rats, who were bred to be poor at solving mazes. They were then asked to run experiments with the rats and collect the data as they usually would. The rats were placed in T-shaped mazes where they had to run down the center and then decide to turn left or turn right. One of the sides of the maze was painted white, while the other was painted dark gray, and it was the rat's job to always turn towards the dark gray side of the maze. The rats who turned towards the dark gray side of the maze received a reward, while the rats who turned towards the white side of the maze did not. The students kept track of how many times each rat turned towards the correct (or dark gray) side of the maze, how many times each rat turned towards the incorrect (or white) side of the maze, and how long it took each rat to make a decision. They repeated this experiment ten times per day, all over the course of five days total, and in the end, they found that the "maze-bright" rats were better at both correctly completing the maze and completing the maze in the fastest time. However, there were actually no "maze-bright" or "maze-dull" rats; these rats were all genetically identical to one another and were randomly divided into the two categories. The two groups of students should have gotten the same results for both kinds of rats, but failed to do so because of observer bias. The entire effect of the experiment was caused by their expectations: they expected that the "maze-bright" rats would perform better and that the "maze-dull" rats would perform worse. Rosenthal and Fode concluded that these results were caused by smaller and more subtle biases on the part of the students. The students were unaware of the fact that they were treating the rats differently. It's possible that they had slightly different criteria for when the two groups of rats finished the maze, that they had the tendency to hit the stopwatch later for the "maze-dull" rats, or that they were paying more attention to the "maze-bright" rats overall. In this way, the students, or the observers, created what looked like a real result, but what was, in reality, totally false.