Imagination inflation is a type of memory distortion that occurs when imagining an event that never happened increases confidence in the memory of the event
Garry, M., Manning, C.G., Loftus, E.F. _et al._ Imagination inflation: Imagining a childhood event inflates confidence that it occurred. _Psychonomic Bulletin & Review_ **3,** 208–214 (1996). https://doi.org/10.3758/BF03212420
Imagining a false event (e.g. caused by an question: have you ever broken a window as a kid?) increases familiarity. This familiarity is often mistaken for evidence that the event occurred (elaborated in "Familiarity misattribution theory").
Closely related to Memory distortion by suggestion
TODO: Research: How strong is this effect in practice?