The recognition and interpretation of unwitting testimony by historians acknowledges that primary sources may contain flaws as well as several layers of evidence, and that there are messages that are not explicit.
[3][4][5] Marwick defined it as a feature of historical evidence to be distinguished from "witting testimony", which is the message of the primary source consciously intended to be conveyed by the author.
[7] Unwitting testimony has been employed by historians to establish the beliefs and customs of past societies particularly in their interpretation of words and phrases, which tend to change meaning over time.
[9][1] The unwitting nature of the testimony include culture-bound views of the observer on events, which some scholars say can lead to a failure in understanding historical texts if ignored.
[7] The concept was also applied to film by Karsten Fledelius, referring to the incidental aspects of reality that slipped into the camera that were unwittingly recorded.