Most of the time, it's referred to as the "Theory of Familiarization" or Era Cues. Quite simply, the method involves trying to recreate the environment, or a part of the environment, of a specific era during an investigation in an attempt to stimulate paranormal activity.
The theory, in part, is based on familiarization, believing that if spirits occupying the location recognize the environment or something positive within it, they will become active and possibly show themselves in some form. The ultimate goal is for this theory to be so effective and stimulating that the end result is an apparition.
The method is usually put into action by playing music of different eras, or one exact era if you're focusing more on an individual situation (music has been more the focus of JPPI investigations using the Signpore Theory), while other approaches might be to recreate the environment visually or to dress the investigators in "period" clothing (a good example is havng the investigators dress in medical attire, e.g., scrubs and lab coats, when investigating an abandoned hospital or clinic).
What are your thoughts on this ?