Observer's paradox

The observer's paradox refers to phenomena where the observation of an event or experiment is influenced by the presence of the observer/investigator.

In linguistics
In the field of sociolinguistics, the term Observer’s Paradox was dubbed by William Labov, who stated with regards to the term:

“the aim of linguistic research in the community must be to find out how people talk when they are not being systematically observed; yet we can only obtain this data by systematic observation.”

The term refers to the challenge sociolinguists face while doing fieldwork, where the task of gathering data on natural speech is undermined by the researcher’s presence itself. As a field worker attempts to observe the daily vernacular of a speaker in an interview, the speaker, aware that their speech will be used for scholarly research, is likely to adopt a formal register. This hypercorrection produces data that is not representative of the speaker’s typical speech, and the paradox lies in the fact that if the researcher were not present, the speaker would use normal vernacular.

Overcoming Observer's Paradox
Labov believed that the style and register of a subject’s speech was determined by the amount of attention the subject paid to their manner of speech. According to J.K. Chamber’s Sociolinguistic Theory, Labov’s “most successful [strategy] in making the subjects forget the unnaturalness of the situation were the recollection of street games and of life-threatening situations. Most reliable in eliciting truly casual speech were fortuitous interruptions by family members and friends while the tape recorder was turned on.” According to Labov, when subjects retell very emotional stories in their life, they are likely to be overtaken by the memory of a significant incident in their life, and therefore would pay less attention to their manner of speech, yielding to a casual style register.

In Labov’s study, “The Social Stratification of ( r ) in New York City Department Stores,” he aims to “see how people use language in context when there is no explicit observation” (p. 43). He accomplishes this task by asking employees of several different New York Department stores a question designed to elicit the same response - the phrase, “Fourth Floor.” He follows the employee’s response by asking, a clarifying question, intended to elicit a formal response. Upon receiving an answer, Labov walks away from the speaker and records what he heard. Here, we find an example of Labov interviewing his subjects with the systematic use of rapid and anonymous observations in studying the linguistic structure of different speech communities. This rapid and anonymous approach to interviewing is likely to ensure subjects will resist closely monitoring their speech.

Other examples

 * In photojournalism and documentary photography, the photographer often attempts to avoid photos that appear posed or staged.
 * In quantum mechanics, Schrödinger's cat is a thought experiment that deals with the issue of quantum indeterminacy.
 * Hawthorne Effect
 * Heisenberg Uncertainty Principle